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Kiriyama A, Kimura S, Yamashita S. Exploring the multiple effects of nifedipine and captopril administration in spontaneously hypertensive rats through pharmacokinetic-pharmacodynamic analyses. Pharmacol Res Perspect 2024; 12:e1249. [PMID: 39017590 PMCID: PMC11253705 DOI: 10.1002/prp2.1249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 06/05/2024] [Accepted: 07/03/2024] [Indexed: 07/18/2024] Open
Abstract
This study assessed the pharmacokinetics (PKs) and pharmacodynamics (PDs) of two antihypertensive drugs, nifedipine and captopril, by exploring their main (blood pressure [BP]) and secondary effects (heart rate [HR] and QT interval [QT]) in spontaneously hypertensive rats. This study aimed to assess the relationship between PKs and PDs. Using these PD parameters, BP, HR, and QT during coadministration were estimated. The coadministration of nifedipine and captopril resulted in an increase in nifedipine's total body clearance (CLtot) and a reduction in its mean residence time (MRT) with an increase in the terminal elimination half-life (t1/2) and volume of distribution at steady state (Vdss) of captopril. However, no significant PK interactions were observed. During monotherapy, BP reduced rapidly following nifedipine infusion. Subsequently, despite the increase in nifedipine plasma concentration, BP recovered, likely because of homeostasis. Similar results were observed with coadministration. Subsequently, BP demonstrated a sustained reduction that was greater than or equal to the additive effect estimated from each PK. Captopril exhibited a minimal effect on HR, except for a transient increase observed immediately after starting infusion, consistent with observations during coadministration. Subsequently, the HR reduction was nearly equal to that calculated from the nifedipine PK. QT prolongation was more rapid with captopril than with nifedipine. Although QT prolongation during the initial 60 min of coadministration was approximately the sum of both effects, the recovery period to baseline QT was faster than that in the simulation.
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Affiliation(s)
- Akiko Kiriyama
- Department of Pharmacokinetics, Faculty of Pharmaceutical SciencesDoshisha Women's College of Liberal ArtsKyotoJapan
| | - Shunsuke Kimura
- Department of Pharmacokinetics, Faculty of Pharmaceutical SciencesDoshisha Women's College of Liberal ArtsKyotoJapan
| | - Shugo Yamashita
- Department of Pharmacokinetics, Faculty of Pharmaceutical SciencesDoshisha Women's College of Liberal ArtsKyotoJapan
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Li H, Ye Q, Wang D, Shi B, Xu W, Zhang S, Han X, Zhang XY, Thompson GJ. Resting State Brain Networks under Inverse Agonist versus Complete Knockout of the Cannabinoid Receptor 1. ACS Chem Neurosci 2024; 15:1669-1683. [PMID: 38575140 PMCID: PMC11027912 DOI: 10.1021/acschemneuro.3c00804] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 03/14/2024] [Accepted: 03/14/2024] [Indexed: 04/06/2024] Open
Abstract
The cannabinoid receptor 1 (CB1) is famous as the target of Δ9-tetrahydrocannabinol (THC), which is the active ingredient of marijuana. Suppression of CB1 is frequently suggested as a drug target or gene therapy for many conditions (e.g., obesity, Parkinson's disease). However, brain networks affected by CB1 remain elusive, and unanticipated psychological effects in a clinical trial had dire consequences. To better understand the whole brain effects of CB1 suppression we performed in vivo imaging on mice under complete knockout of the gene for CB1 (cnr1-/-) and also under the CB1 inverse agonist rimonabant. We examined white matter structural changes and brain function (network activity and directional uniformity) in cnr1-/- mice. In cnr1-/- mice, white matter (in both sexes) and functional directional uniformity (in male mice) were altered across the brain but network activity was largely unaltered. Conversely, under rimonabant, functional directional uniformity was not altered but network activity was altered in cortical regions, primarily in networks known to be altered by THC (e.g., neocortex, hippocampal formation). However, rimonabant did not alter many brain regions found in both our cnr1-/- results and previous behavioral studies of cnr1-/- mice (e.g., thalamus, infralimbic area). This suggests that chronic loss of cnr1 is substantially different from short-term suppression, subtly rewiring the brain but largely maintaining the network activity. Our results help explain why pathological mutations in CB1 (e.g., chronic pain) do not always provide insight into the side effects of CB1 suppression (e.g., clinical depression), and thus urge more preclinical studies for any drugs that suppress CB1.
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Affiliation(s)
- Hui Li
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
| | - Qiong Ye
- High
Magnetic Field Laboratory, Hefei Institutes
of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Da Wang
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
- School
of Life Science and Technology, ShanghaiTech
University, Shanghai 201210, China
| | - Bowen Shi
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
- School
of Life Science and Technology, ShanghaiTech
University, Shanghai 201210, China
| | - Wenjing Xu
- Institute
of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China
- Key
Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai 200433, China
| | - Shuning Zhang
- iHuman
Institute, ShanghaiTech University, Shanghai 201210, China
- School
of Life Science and Technology, ShanghaiTech
University, Shanghai 201210, China
| | - Xiaoyang Han
- Institute
of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China
- Key
Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai 200433, China
| | - Xiao-Yong Zhang
- Institute
of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai 200433, China
- Key
Laboratory of Computational Neuroscience and Brain-Inspired Intelligence, Fudan University, Ministry of Education, Shanghai 200433, China
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Güemes Gonzalez A, Carnicer-Lombarte A, Hilton S, Malliaras G. A multivariate physiological model of vagus nerve signalling during metabolic challenges in anaesthetised rats for diabetes treatment. J Neural Eng 2023; 20:056033. [PMID: 37757803 DOI: 10.1088/1741-2552/acfdcd] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 09/27/2023] [Indexed: 09/29/2023]
Abstract
Objective.This study aims to develop a comprehensive decoding framework to create a multivariate physiological model of vagus nerve transmission that reveals the complex interactions between the nervous and metabolic systems.Approach.Vagus nerve activity was recorded in female Sprague-Dawley rats using gold hook microwires implanted around the left cervical vagus nerve. The rats were divided into three experimental cohorts (intact nerve, ligation nerve for recording afferent activation, and ligation for recording efferent activation) and metabolic challenges were administered to change glucose levels while recording the nerve activity. The decoding methodology involved various techniques, including continuous wavelet transformation, extraction of breathing rate (BR), and correlation of neural metrics with physiological signals.Main results.Decrease in glucose level was consistently negatively correlated with an increase in the firing activity of the intact vagus nerve that was found to be conveyed by both afferent and efferent pathways, with the afferent response being more similar to the one on the intact nerve. A larger variability was observed in the sensory and motor responses to hyperglycaemia. A novel strategy to extract the BR over time based on inter-burst-interval is also presented. The vagus afferent was found to encode breathing information through amplitude and firing rate modulation. Modulations of the signal amplitude were also observed due to changes in heart rate in the intact and efferent recordings, highlighting the parasympathetic control of the heart.Significance.The analytical framework presented in this study provides an integrative understanding that considers the relationship between metabolic, cardiac, and breathing signals and contributes to the development of a multivariable physiological model for the transmission of vagus nerve signals. This work progresses toward the development of closed-loop neuro-metabolic therapeutic systems for diabetes.
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Affiliation(s)
- Amparo Güemes Gonzalez
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, United Kingdom
| | - Alejandro Carnicer-Lombarte
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, United Kingdom
| | - Sam Hilton
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, United Kingdom
| | - George Malliaras
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, United Kingdom
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McPherson JG, Bandres MF. Neural population dynamics reveal that motor-targeted intraspinal microstimulation preferentially depresses nociceptive transmission in spinal cord injury-related neuropathic pain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.27.550880. [PMID: 37546721 PMCID: PMC10402167 DOI: 10.1101/2023.07.27.550880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
The purpose of this study is to determine whether intraspinal microstimulation (ISMS) intended to enhance voluntary motor output after spinal cord injury (SCI) modulates neural population-level spinal responsiveness to nociceptive sensory feedback. The study was conducted in vivo in three cohorts of rats: neurologically intact, chronic SCI without behavioral signs of neuropathic pain, and chronic SCI with SCI-related neuropathic pain (SCI-NP). Nociceptive sensory feedback was induced by application of graded mechanical pressure to the plantar surface of the hindpaw before, during, and after periods of sub-motor threshold ISMS delivered within the motor pools of the L5 spinal segment. Neural population-level responsiveness to nociceptive feedback was recorded throughout the dorso-ventral extent of the L5 spinal segment using dense multi-channel microelectrode arrays. Whereas motor-targeted ISMS reduced nociceptive transmission across electrodes in neurologically intact animals both during and following stimulation, it was not associated with altered nociceptive transmission in rats with SCI that lacked behavioral signs of neuropathic pain. Surprisingly, nociceptive transmission was reduced both during and following motor-targeted ISMS in rats with SCI-NP, and to an extent comparable to that of neurologically intact animals. The mechanisms underlying the differential anti-nociceptive effects of motor-targeted ISMS are unclear, although they may be related to differences in the intrinsic active membrane properties of spinal neurons across the cohorts. Nevertheless, the results of this study support the notion that it may be possible to purposefully engineer spinal stimulation-based therapies that afford multi-modal rehabilitation benefits, and specifically that it may be possible to do so for the individuals most in need - i.e., those with SCI-related movement impairments and SCI-NP.
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Affiliation(s)
- Jacob G. McPherson
- Program in Physical Therapy, Washington University School of Medicine
- Department of Anesthesiology, Washington University School of Medicine
- Washington University Pain Center, Washington University School of Medicine
- Program in Neurosciences; Washington University School of Medicine
- Department of Biomedical Engineering; Washington University in St. Louis
| | - Maria F. Bandres
- Program in Physical Therapy, Washington University School of Medicine
- Department of Biomedical Engineering; Washington University in St. Louis
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The effect of urethane and MS-222 anesthesia on the electric organ discharge of the weakly electric fish Apteronotus leptorhynchus. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2023; 209:437-457. [PMID: 36799986 DOI: 10.1007/s00359-022-01606-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2022] [Revised: 12/16/2022] [Accepted: 12/20/2022] [Indexed: 02/18/2023]
Abstract
Urethane and MS-222 are agents widely employed for general anesthesia, yet, besides inducing a state of unconsciousness, little is known about their neurophysiological effects. To investigate these effects, we developed an in vivo assay using the electric organ discharge (EOD) of the weakly electric fish Apteronotus leptorhynchus as a proxy for the neural output of the pacemaker nucleus. The oscillatory neural activity of this brainstem nucleus drives the fish's EOD in a one-to-one fashion. Anesthesia induced by urethane or MS-222 resulted in pronounced decreases of the EOD frequency, which lasted for up to 3 h. In addition, each of the two agents caused a manifold increase in the generation of transient modulations of the EOD known as chirps. The reduction in EOD frequency can be explained by the modulatory effect of urethane on neurotransmission, and by the blocking of voltage-gated sodium channels by MS-222, both within the circuitry controlling the neural oscillations of the pacemaker nucleus. The present study demonstrates a marked effect of urethane and MS-222 on neural activity within the central nervous system and on the associated animal's behavior. This calls for caution when conducting neurophysiological experiments under general anesthesia and interpreting their results.
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Johnson TD, Keefe KR, Rangel LM. Stimulation-induced entrainment of hippocampal network activity: Identifying optimal input frequencies. Hippocampus 2023; 33:85-95. [PMID: 36624658 PMCID: PMC10068596 DOI: 10.1002/hipo.23490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 11/29/2022] [Accepted: 12/04/2022] [Indexed: 01/11/2023]
Abstract
The hippocampus contains rich oscillatory activity, with continuous ebbs and flows of rhythmic currents that constrain its ability to integrate inputs. During associative learning, the hippocampus must integrate inputs from a range of sources carrying information about events and the contexts in which they occur. Under these circumstances, temporal coordination of activity between sender and receiver is likely essential for successful communication. Previously, it has been shown that the coordination of rhythmic activity between the lateral entorhinal cortex (LEC) and the CA1 region of the hippocampus is tightly correlated with the onset of learning in an associative learning task. We aimed to examine whether rhythmic inputs from the LEC in specific frequency ranges were sufficient to enhance the temporal coordination of activity in downstream CA1. In urethane-anesthetized rats, we applied extracellular low-intensity alternating current stimulation across the length of the LEC. Using this method, we aimed to phase-bias ongoing neuronal activity in LEC at a range of different frequencies (from 1.25 to 55 Hz). Rhythmic stimulation of LEC at both 35 and 50 Hz increased the proportion of CA1 neurons significantly entrained to the phase of the applied stimulation current. A subset of stimulation frequencies modified CA1 spiking relationships to the phase of local ongoing CA1 oscillations, with each stimulation frequency exerting a unique influence upon downstream CA1, often in frequency ranges outside the target stimulation frequency. These results suggest there are optimal frequencies for LEC-CA1 communication, and that different profiles of LEC rhythms likely have distinct outcomes upon CA1 processing.
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Affiliation(s)
- Teryn D Johnson
- Department of Cognitive Science, University of California, San Diego, California, USA
| | | | - Lara M Rangel
- Department of Cognitive Science, University of California, San Diego, California, USA
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Mun J, Lee J, Park E, Park SM. Frequency-dependent depression of the NTS synapse affects the temporal response of the antihypertensive effect of auricular vagus nerve stimulation (aVNS). J Neural Eng 2022; 19. [PMID: 35905707 DOI: 10.1088/1741-2552/ac857a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Accepted: 07/29/2022] [Indexed: 11/12/2022]
Abstract
OBJECTIVES Auricular vagus nerve stimulation (aVNS) has recently emerged as a promising neuromodulation modality for blood pressure (BP) reduction due to its ease of use although its efficacy is still limited compared to direct baroreflex stimulation. Previous studies have also indicated that synaptic depression of nucleus tractus solitarius (NTS) in the baroreflex pathway depends on stimulus frequency. However, the nature of this frequency dependence phenomenon on antihypertensive effect has been unknown for aVNS. We aimed to investigate the antihypertensive effect of aVNS considering frequency-dependent depression characteristic in the NTS synapse. We explored NTS activation and BP reduction induced by aVNS and by direct secondary neuron stimulation (DS). APPROACH Both protocols were performed with recording of NTS activation and BP response with stimulation for each frequency parameter (2, 4, 20, 50, and 80 Hz). MAIN RESULTS The BP recovery time constant was significantly dependent on the frequency of DS and aVNS (DS - 2 Hz: 8.17 ± 4.98; 4 Hz: 9.73 ± 6.3; 20 Hz: 6.61 ± 3.28; 50 Hz: 4.93 ± 1.65; 80 Hz: 4.00 ± 1.43, p < 0.001, Kruskal-Wallis H-test / aVNS - 2 Hz: 4.02 ± 2.55; 4 Hz: 8.13 ± 4.05; 20 Hz: 6.40 ± 3.16; 50 Hz: 5.18 ± 2.37; 80 Hz: 3.13 ± 1.29, p < 0.05, Kruskal-Wallis H-test) despite no significant BP reduction at 2 Hz compared to sham groups (p > 0.05, Mann-Whitney U-test). SIGNIFICANCE Our observations suggest that the antihypertensive effect of aVNS is influenced by the characteristics of frequency-dependent synaptic depression in the NTS neuron in terms of the BP recovery time. These findings suggest that the antihypertensive effect of aVNS can be improved with further understanding of the neurological properties of the baroreflex associated with aVNS, which is critical to push this new modality for clinical interpretation.
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Affiliation(s)
- Junseung Mun
- Department of Convergence IT Engineering, POSTECH, IMSLAB, 2nd floor, C5 building, POSTECH 77, Cheongam-ro, Nam-gu, South Korea, Pohang, 37673, Korea (the Republic of)
| | - Jiho Lee
- Department of Convergence IT Engineering, Pohang University of Science and Technology, IMSLAB, 2nd floor, C5 building, POSTECH 77, Cheongam-ro, Nam-gu, South Korea, Pohang, 37673, Korea (the Republic of)
| | - Eunkyoung Park
- Department of Medical and Mechatronics Engineering, Soonchunhyang University, Chungnam 31538, Asan, Korea, Asan, Chungcheongnam-do, 31538, Korea (the Republic of)
| | - Sung-Min Park
- POSTECH, IMSLAB, 2nd floor, C5 building, POSTECH 77, Cheongam-ro, Nam-gu, South Korea, Pohang, 37673, Korea (the Republic of)
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López-Canales OA, Pavón N, Ubaldo-Reyes LM, Juárez-Oropeza MA, Torres-Durán PV, Regla I, Paredes-Carbajal MC. Characterization of hypotensive and vasorelaxant effects of PHAR-DBH-Me a new cannabinoid receptor agonist. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY 2022; 26:77-86. [PMID: 35203058 PMCID: PMC8890940 DOI: 10.4196/kjpp.2022.26.2.77] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/30/2021] [Accepted: 12/04/2021] [Indexed: 12/04/2022]
Abstract
The effect of PHAR-DBH-Me, a cannabinoid receptor agonist, on different cardiovascular responses in adult male rats was analyzed. The blood pressure was measured directly and indirectly. The coronary flow was measured by Langendorff preparation, and vasomotor responses induced by PHAR-DBH-Me in aortic rings pre-contracted with phenylephrine (PHEN) were analyzed. The intravenous injection of the compound PHAR-DBH-Me (0.018–185 µg/kg) resulted in decreased blood pressure; maximum effect was observed at the dose of 1,850 µg/kg. A concentration-dependent increase in the coronary flow was observed in a Langendorff preparation. In the aortic rings, with and without endothelium, pre-contracted with PHEN (10–6 M), the addition of PHAR-DBH-Me to the superfusion solution (10–12–10–5 M), produced a vasodilator response, which depends on the concentration and presence of the endothelium. L-NAME inhibited these effects. Addition of CB1 receptor antagonist (AM 251) did not modify the response, while CB2 receptor antagonist (AM630) decreased the potency of relaxation elicited by PHAR-DBH-Me. Indomethacin shifted the curve concentration-response to the left and produced an increase in the magnitude of the maximum endothelium dependent response to this compound. The maximum effect of PHAR-DBH-Me was observed with the concentration of 10–5 M. These results show that PHAR-DBH-Me has a concentration-dependent and endothelium-dependent vasodilator effect through CB2 receptor. This vasodilation is probably mediated by the synthesis/release of NO. On the other hand, it is suggested that PHAR-DBH-Me also induces the release of a vasoconstrictor prostanoid.
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Affiliation(s)
- Oscar Alberto López-Canales
- Department of Physiology, School of Medicine, National Autonomous University of Mexico, Mexico City 04510, Mexico
| | - Natalia Pavón
- Department of Pharmacology, National Institute of Cardiology, Mexico City 14080, Mexico
| | - Laura Matilde Ubaldo-Reyes
- Department of Anatomy, School of Medicine, National Autonomous University of Mexico, Mexico City 04510, Mexico
| | - Marco Antonio Juárez-Oropeza
- Department of Biochemistry, School of Medicine, National Autonomous University of Mexico, Mexico City 04510, Mexico
| | | | - Ignacio Regla
- Drug Synthesis Laboratory, UMIEZ, Zaragoza School of Higher Education, National Autonomous University of Mexico, Mexico City 09230, Mexico
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Silver NRG, Ward-Flanagan R, Dickson CT. Long-term stability of physiological signals within fluctuations of brain state under urethane anesthesia. PLoS One 2021; 16:e0258939. [PMID: 34695166 PMCID: PMC8544839 DOI: 10.1371/journal.pone.0258939] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Accepted: 10/10/2021] [Indexed: 11/30/2022] Open
Abstract
Urethane, an acute laboratory anesthetic, produces distinct neurophysiological and physiological effects creating an effective model of the dynamics of natural sleep. As a model of both sleep-like neurophysiological activity and the downstream peripheral function urethane is used to model a variety of physiological and pathophysiological processes. As urethane is typically administered as a single-bolus dose, it is unclear the stability of peripheral physiological functions both within and between brain-states under urethane anesthesia. In this present study, we recorded respiration rate and heart rate concurrently with local field potentials from the neocortex and hippocampus to determine the stability of peripheral physiological functions within and between brain-states under urethane anesthesia. Our data shows electroencephalographic characteristics and breathing rate are remarkable stable over long-term recordings within minor reductions in heart rate on the same time scale. Our findings indicate that the use of urethane to model peripheral physiological functions associated with changing brain states are stable during long duration experiments.
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Affiliation(s)
| | - Rachel Ward-Flanagan
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
| | - Clayton T. Dickson
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, Canada
- Department of Psychology, University of Alberta, Edmonton, Canada
- Department of Physiology, University of Alberta, Edmonton, Canada
- Department of Anaesthesiology & Pain Medicine, University of Alberta, Edmonton, Canada
- * E-mail:
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10
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Sabetian P, Yadollahi A, Yoo PB. Reduced genioglossus muscle activity caused by fluid overload in anesthetized rats. Physiol Rep 2020; 8:e14445. [PMID: 32633469 PMCID: PMC7339833 DOI: 10.14814/phy2.14445] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/16/2020] [Accepted: 04/19/2020] [Indexed: 12/19/2022] Open
Abstract
INTRODUCTION Although the precise cause of obstructive sleep apnea (OSA) remains unknown, various anatomical or structural factors are thought to influence upper airway patency. Recent clinical studies show that OSA is frequently observed among patients with fluid-retaining states, such as heart/renal failure and postsurgery. It is important to note that a cause-effect relationship is not yet established, and our understanding of the effects of fluid overload is limited. The goal of this study was to investigate an animal model that can characterize the physiological changes that occur in response to fluid overload. METHOD Acute nonsurvival experiments were conducted in 16 Sprague-Dawley rats. Rats were initially anesthetized by inhaled isoflurane, while the femoral vein was cannulated and urethane (1.2-1.5 g/Kg body weight) was gradually delivered intravenously to induce anesthesia. Additional doses of urethane were delivered as necessary to maintain a surgical plane of anesthesia. A surgical incision was made on the cervical area to catheterize carotid artery to measure blood pressure. A pair of stainless-steel wires was injected into the tongue to measure genioglossus muscle activity (GGEMG). All physiological measurements were recorded as intravenous infusion of saline was provided to the rat (infusion rate = 22 ml/kg over 30 min). RESULTS Acute saline overloading resulted in a 33% decrease in GGEMG, when compared to baseline. There was also a gradual drop in the respiratory rate (13% decrease) that reached statistical significance at 10 min after infusion was stopped. The blood pressure exhibited a 14% increase which subsequently returned to baseline within 40 min stopping infusion. There were no significant changes in the heart rate. CONCLUSION The results of this study indicate that systemic fluid overload can affect significant changes in different physiological systems including reduction in genioglossus muscle activity, increase in blood pressure, and change autonomic nervous system function.
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Affiliation(s)
- Parisa Sabetian
- Institute of Biomaterials and Biomedical EngineeringUniversity of TorontoTorontoONCanada
| | - Azadeh Yadollahi
- Institute of Biomaterials and Biomedical EngineeringUniversity of TorontoTorontoONCanada
- Toronto Rehabilitation InstituteUniversity Health NetworkUniversity of TorontoTorontoONCanada
| | - Paul B. Yoo
- Institute of Biomaterials and Biomedical EngineeringUniversity of TorontoTorontoONCanada
- Toronto Rehabilitation InstituteUniversity Health NetworkUniversity of TorontoTorontoONCanada
- Department of Electrical and Computer EngineeringUniversity of TorontoTorontoONCanada
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11
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Fraser MO, Smith PP, Sullivan MP, Bjorling DE, Campeau L, Andersson KE, Yoshiyama M. Best practices for cystometric evaluation of lower urinary tract function in muriform rodents. Neurourol Urodyn 2020; 39:1868-1884. [PMID: 32511810 DOI: 10.1002/nau.24415] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 04/30/2020] [Accepted: 05/21/2020] [Indexed: 12/21/2022]
Abstract
AIMS Rodent cystometry has provided valuable insights into the impact of the disease, injury, and aging on the cellular and molecular pathways, neurologic processes, and biomechanics of lower urinary tract function. The purpose of this white paper is to highlight the benefits and shortcomings of different experimental methods and strategies and to provide guidance on the proper interpretation of results. METHODS Literature search, selection of articles, and conclusions based on discussions among a panel of workers in the field. RESULTS A range of cystometric tests and techniques used to explore biological phenomena relevant to the lower urinary tract are described, the advantages and disadvantages of various experimental conditions are discussed, and guidance on the practical aspects of experimental execution and proper interpretation of results are provided. CONCLUSIONS Cystometric evaluation of rodents comprises an extensive collection of functional tests that can be performed under a variety of experimental conditions. Decisions regarding which approaches to choose should be determined by the specific questions to be addressed and implementation of the test should follow standardized procedures.
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Affiliation(s)
- Matthew O Fraser
- Division of Urology, Department of Surgery, Duke University Medical Center, Durham, North Carolina.,Department of Research and Development, Durham Veterans Affairs Medical Center, Durham, North Carolina
| | - Phillip P Smith
- Division of Urology, Department of Surgery, University of Connecticut Medical Center, Farmington, Connecticut
| | - Maryrose P Sullivan
- Division of Urology, Department of Surgery, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts.,Department of Research and Development, Veterans Affairs Boston Healthcare System, Boston, Massachusetts
| | - Dale E Bjorling
- Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Lysanne Campeau
- Division of Urology, Department of Surgery, McGill University, Montreal, Quebec, Canada
| | - Karl-Erik Andersson
- Institute for Regenerative Medicine, Wake Forest University School of Medicine, Winston Salem, North Carolina.,Department of Laboratory Medicine, Lund University, Lund, Sweden
| | - Mitsuharu Yoshiyama
- Department of Urology, University of Yamanashi Graduate School of Medicine, Chuo, Yamanashi, Japan
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12
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Lehto LJ, Canna A, Wu L, Sierra A, Zhurakovskaya E, Ma J, Pearce C, Shaio M, Filip P, Johnson MD, Low WC, Gröhn O, Tanila H, Mangia S, Michaeli S. Orientation selective deep brain stimulation of the subthalamic nucleus in rats. Neuroimage 2020; 213:116750. [PMID: 32198048 DOI: 10.1016/j.neuroimage.2020.116750] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 02/22/2020] [Accepted: 03/13/2020] [Indexed: 11/28/2022] Open
Abstract
Deep brain stimulation (DBS) has become an important tool in the management of a wide spectrum of diseases in neurology and psychiatry. Target selection is a vital aspect of DBS so that only the desired areas are stimulated. Segmented leads and current steering have been shown to be promising additions to DBS technology enabling better control of the stimulating electric field. Recently introduced orientation selective DBS (OS-DBS) is a related development permitting sensitization of the stimulus to axonal pathways with different orientations by freely controlling the primary direction of the electric field using multiple contacts. Here, we used OS-DBS to stimulate the subthalamic nucleus (STN) in healthy rats while simultaneously monitoring the induced brain activity with fMRI. Maximal activation of the sensorimotor and basal ganglia-thalamocortical networks was observed when the electric field was aligned mediolaterally in the STN pointing in the lateral direction, while no cortical activation was observed with the electric field pointing medially to the opposite direction. Such findings are consistent with mediolateral main direction of the STN fibers, as seen with high resolution diffusion imaging and histology. The asymmetry of the OS-DBS dipolar field distribution using three contacts along with the potential stimulation of the internal capsule, are also discussed. We conclude that OS-DBS offers an additional degree of flexibility for optimization of DBS of the STN which may enable a better treatment response.
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Affiliation(s)
- Lauri J Lehto
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Antonietta Canna
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA; Department of Medicine, Surgery and Dentistry, Scuola Medica Salernitana, University of Salerno, Salerno, Italy
| | - Lin Wu
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Alejandra Sierra
- A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Ekaterina Zhurakovskaya
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA; A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Jun Ma
- Department of Neurosurgery, University of Minnesota, Minneapolis, USA
| | - Clairice Pearce
- Department of Neurosurgery, University of Minnesota, Minneapolis, USA
| | - Maple Shaio
- Department of Neurosurgery, University of Minnesota, Minneapolis, USA
| | - Pavel Filip
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA; First Department of Neurology, Faculty of Medicine, Masaryk University and University Hospital of St. Anne, Brno, Czech Republic
| | - Matthew D Johnson
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, USA
| | - Walter C Low
- Department of Neurosurgery, University of Minnesota, Minneapolis, USA
| | - Olli Gröhn
- A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Heikki Tanila
- A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Silvia Mangia
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA
| | - Shalom Michaeli
- Center for Magnetic Resonance Research, University of Minnesota, Minneapolis, MN, USA.
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13
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Fabiyi-Edebor TD. Vitamin C ameliorated cardiac autonomic neuropathy in type 2 diabetic rats. World J Diabetes 2020; 11:52-65. [PMID: 32180894 PMCID: PMC7061237 DOI: 10.4239/wjd.v11.i3.52] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 12/07/2019] [Accepted: 01/13/2020] [Indexed: 02/05/2023] Open
Abstract
BACKGROUND Vitamin C (VC) is a common antioxidant with cell protection potentials. However, its possible protective effect on cardiac autonomic nerves from diabetic induced insults is yet to be explored.
AIM To investigate the effects of VC on diabetic cardiac autonomic neuropathy.
METHODS Thirty male Wistar rats were equally grouped into control, diabetic and diabetic + VC. Type 2 diabetes was induced with fructose diet and alloxan. VC (1 g/kg) was administered for 4 wk via oral canula. Blood pressure and heart rate were measured non-invasively using tail flick blood pressure monitor. Spectral analysis of heart rate variability (HRV) was used to assess cardiac autonomic neuropathy. Blood was collected from the ocular sinus for biochemical analysis. Urethane (1 g/kg-ip) was used for anaesthesia prior to HRV and cervical dislocation to harvest hearts. Intracardiac autonomic nerve was assessed using tyrosine hydroxylase immunohistochemistry on fixed heart sections.
RESULTS Results were analysed using ANOVA at α0.05. Unlike VC and control groups, diabetic rats showed significantly (P < 0.0001) reduced HRV, increased heart-rate and blood pressure, initial increase in cardiac tyrosine hydroxylase activities at week-2 and sparse activity at week-4 of diabetes. Furthermore, apolipoprotein B, Oxidative stress and inflammatory markers were significantly (P < 0.01) reduced in VC treated rats.
CONCLUSION VC possesses cardio-autonomic nerve protective potential and ameliorates the symptoms of cardiac autonomic neuropathy in type 2 diabetes. The possible mechanisms via which VC exert these effects may be via downregulation of oxidative stress, inflammation and apolipoprotein B.
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14
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Yamaguchi N, Mimura K, Okada S. Prostaglandin E2 receptor EP3 subtype in the paraventricular hypothalamic nucleus mediates corticotropin-releasing factor-induced elevation of plasma noradrenaline levels in rats. Eur J Pharmacol 2019; 863:172693. [DOI: 10.1016/j.ejphar.2019.172693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 09/17/2019] [Accepted: 09/23/2019] [Indexed: 02/08/2023]
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15
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Kloza M, Baranowska-Kuczko M, Toczek M, Kusaczuk M, Sadowska O, Kasacka I, Kozłowska H. Modulation of Cardiovascular Function in Primary Hypertension in Rat by SKA-31, an Activator of KCa2.x and KCa3.1 Channels. Int J Mol Sci 2019; 20:ijms20174118. [PMID: 31450834 PMCID: PMC6747311 DOI: 10.3390/ijms20174118] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/17/2019] [Accepted: 08/21/2019] [Indexed: 12/11/2022] Open
Abstract
The aim of this study was to investigate the hemodynamic effects of SKA-31, an activator of the small (KCa2.x) and intermediate (KCa3.1) conductance calcium-activated potassium channels, and to evaluate its influence on endothelium-derived hyperpolarization (EDH)-KCa2.3/KCa3.1 type relaxation in isolated endothelium-intact small mesenteric arteries (sMAs) from spontaneously hypertensive rats (SHRs). Functional in vivo and in vitro experiments were performed on SHRs or their normotensive controls, Wistar-Kyoto rats (WKY). SKA-31 (1, 3 and 10 mg/kg) caused a brief decrease in blood pressure and bradycardia in both SHR and WKY rats. In phenylephrine-pre-constricted sMAs of SHRs, SKA-31 (0.01–10 µM)-mediated relaxation was reduced and SKA-31 potentiated acetylcholine-evoked endothelium-dependent relaxation. Endothelium denudation and inhibition of nitric oxide synthase (eNOS) and cyclooxygenase (COX) by the respective inhibitors l-NAME or indomethacin, attenuated SKA-31-mediated vasorelaxation. The inhibition of KCa3.1, KCa2.3, KIR and Na+/K+-ATPase by TRAM-34, UCL1684, Ba2+ and ouabain, respectively, reduced the potency and efficacy of the EDH-response evoked by SKA-31. The mRNA expression of eNOS, prostacyclin synthase, KCa2.3, KCa3.1 and KIR were decreased, while Na+/K+-ATPase expression was increased. Collectively, SKA-31 promoted hypotension and vasodilatation, potentiated agonist-stimulated vasodilation, and maintained KCa2.3/KCa3.1-EDH-response in sMAs of SHR with downstream signaling that involved KIR and Na+/K+-ATPase channels. In view of the importance of the dysfunction of endothelium-mediated vasodilatation in the mechanism of hypertension, application of activators of KCa2.3/KCa3.1 channels such as SKA-31 seem to be a promising avenue in pharmacotherapy of hypertension.
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Affiliation(s)
- Monika Kloza
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Marta Baranowska-Kuczko
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
- Department of Clinical Pharmacy, Medical University of Białystok, 15-222 Białystok, Poland
| | - Marek Toczek
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Magdalena Kusaczuk
- Department of Pharmaceutical Biochemistry, Medical University of Białystok, 15-222 Białystok, Poland
| | - Olga Sadowska
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Irena Kasacka
- Department of Histology and Cytophysiology, Medical University of Białystok, 15-222 Białystok, Poland
| | - Hanna Kozłowska
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, 15-222 Białystok, Poland.
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16
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Munting LP, Derieppe MP, Suidgeest E, Denis de Senneville B, Wells JA, van der Weerd L. Influence of different isoflurane anesthesia protocols on murine cerebral hemodynamics measured with pseudo-continuous arterial spin labeling. NMR IN BIOMEDICINE 2019; 32:e4105. [PMID: 31172591 PMCID: PMC6772066 DOI: 10.1002/nbm.4105] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 02/22/2019] [Accepted: 03/14/2019] [Indexed: 05/15/2023]
Abstract
Arterial spin labeling (ASL)-MRI can noninvasively map cerebral blood flow (CBF) and cerebrovascular reactivity (CVR), potential biomarkers of cognitive impairment and dementia. Mouse models of disease are frequently used in translational MRI studies, which are commonly performed under anesthesia. Understanding the influence of the specific anesthesia protocol used on the measured parameters is important for accurate interpretation of hemodynamic studies with mice. Isoflurane is a frequently used anesthetic with vasodilative properties. Here, the influence of three distinct isoflurane protocols was studied with pseudo-continuous ASL in two different mouse strains. The first protocol was a free-breathing set-up with medium concentrations, the second a free-breathing set-up with low induction and maintenance concentrations, and the third a set-up with medium concentrations and mechanical ventilation. A protocol with the vasoconstrictive anesthetic medetomidine was used as a comparison. As expected, medium isoflurane anesthesia resulted in significantly higher CBF and lower CVR values than medetomidine (median whole-brain CBF of 157.7 vs 84.4 mL/100 g/min and CVR of 0.54 vs 51.7% in C57BL/6 J mice). The other two isoflurane protocols lowered the CBF and increased the CVR values compared with medium isoflurane anesthesia, without obvious differences between them (median whole-brain CBF of 138.9 vs 131.7 mL/100 g/min and CVR of 10.0 vs 9.6%, in C57BL/6 J mice). Furthermore, CVR was shown to be dependent on baseline CBF, regardless of the anesthesia protocol used.
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Affiliation(s)
- Leon P. Munting
- Department of RadiologyLeiden University Medical CenterLeidenthe Netherlands
- Department of Human GeneticsLeiden University Medical CenterLeidenthe Netherlands
| | - Marc P.P. Derieppe
- Department of RadiologyLeiden University Medical CenterLeidenthe Netherlands
- Prinses Máxima Center for Pediatric OncologyUniversity Medical Center UtrechtUtrechtthe Netherlands
| | - Ernst Suidgeest
- Department of RadiologyLeiden University Medical CenterLeidenthe Netherlands
| | - Baudouin Denis de Senneville
- Department of RadiotherapyUniversity Medical Center UtrechtUtrechtthe Netherlands
- Institut de Mathématiques de BordeauxUniversité Bordeaux/CNRS UMR 5251/INRIABordeaux‐Sud‐OuestFrance
| | - Jack A. Wells
- Division of Medicine, UCL Centre for Advanced Biomedical ImagingUniversity College LondonLondonUK
| | - Louise van der Weerd
- Department of RadiologyLeiden University Medical CenterLeidenthe Netherlands
- Department of Human GeneticsLeiden University Medical CenterLeidenthe Netherlands
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17
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Sharma HS, Muresanu DF, Nozari A, Castellani RJ, Dey PK, Wiklund L, Sharma A. Anesthetics influence concussive head injury induced blood-brain barrier breakdown, brain edema formation, cerebral blood flow, serotonin levels, brain pathology and functional outcome. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2019; 146:45-81. [PMID: 31349932 DOI: 10.1016/bs.irn.2019.06.006] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Several lines of evidences show that anesthetics influence neurotoxicity and neuroprotection. The possibility that different anesthetic agents potentially influence the pathophysiological and functional outcome following neurotrauma was examined in a rat model of concussive head injury (CHI). The CHI was produced by an impact of 0.224N on the right parietal bone by dropping a weight of 114.6g from a 20cm height under different anesthetic agents, e.g., inhaled ether anesthesia or intraperitoneally administered ketamine, pentobarbital, equithesin or urethane anesthesia. Five hour CHI resulted in profound volume swelling and brain edema formation in both hemispheres showing disruption of the blood-brain barrier (BBB) to Evans blue and radioiodine. A marked decrease in the cortical CBF and a profound increase in plasma or brain serotonin levels were seen at this time. Neuronal damages were present in several parts of the brain. These pathological changes were most marked in CHI under ether anesthesia followed by ketamine (35mg/kg, i.p.), pentobarbital (50mg/kg, i.p.), equithesin (3mL/kg, i.p.) and urethane (1g/kg, i.p.). The functional outcome on Rota Rod performances or grid walking tests was also most adversely affected after CHI under ether anesthesia followed by pentobarbital, equithesin and ketamine. Interestingly, the plasma and brain serotonin levels strongly correlated with the development of brain edema in head injured animals in relation to different anesthetic agents used. These observations suggest that anesthetic agents are detrimental to functional and pathological outcomes in CHI probably through influencing the circulating plasma and brain serotonin levels, not reported earlier. Whether anesthetics could also affect the efficacy of different neuroprotective agents in CNS injuries is a new subject that is currently being examined in our laboratory.
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Affiliation(s)
- Hari Shanker Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden.
| | - Dafin Fior Muresanu
- Department of Clinical Neurosciences, University of Medicine & Pharmacy, Cluj-Napoca, Romania; "RoNeuro" Institute for Neurological Research and Diagnostic, Cluj-Napoca, Romania
| | - Ala Nozari
- Anesthesia and Critical Care, Massachusetts General Hospital, Boston, MA, United States
| | - Rudy J Castellani
- Department of Pathology, University of Maryland, Baltimore, MD, United States
| | - Prasanta Kumar Dey
- Neurophysiology Research Unit, Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, Uttar Pradesh, India
| | - Lars Wiklund
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
| | - Aruna Sharma
- International Experimental Central Nervous System Injury & Repair (IECNSIR), Department of Surgical Sciences, Anesthesiology & Intensive Care Medicine, Uppsala University Hospital, Uppsala University, Uppsala, Sweden
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18
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Kossakowski R, Schlicker E, Toczek M, Weresa J, Malinowska B. Cannabidiol Affects the Bezold-Jarisch Reflex via TRPV1 and 5-HT 3 Receptors and Has Peripheral Sympathomimetic Effects in Spontaneously Hypertensive and Normotensive Rats. Front Pharmacol 2019; 10:500. [PMID: 31178718 PMCID: PMC6538767 DOI: 10.3389/fphar.2019.00500] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 04/23/2019] [Indexed: 12/17/2022] Open
Abstract
Cannabidiol (CBD) is a nonpsychotropic constituent of Cannabis sativa L. It is suggested to be useful in hypertension. Under in vitro conditions, it activates vanilloid TRPV1 and inhibits serotonin 5-HT3 receptors, i.e., receptors involved in the Bezold-Jarisch reflex stimulation. The aim of our study was to compare the cardiovascular effects of CBD in spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats. Experiments were performed on conscious, urethane-anesthetized, and pithed rats. In pithed SHR and WKY, CBD increased heart rate (HR) and systolic blood pressure (SBP) and decreased diastolic BP (DBP) in a manner insensitive to adrenalectomy. Propranolol strongly impaired the CBD-induced increases in HR and SBP without affecting the decreases in DBP. Desipramine also reduced the CBD-induced effects on HR and SBP and further increased its effects on DBP. In anesthetized rats, bolus i.v. injection of single doses of CBD induced short-lasting decreases in HR, SBP, and DBP, stronger in SHR than in WKY and prevented by bilateral vagotomy. The CBD-induced fall in HR but not in BP was diminished by the TRPV1 receptor antagonist capsazepine and almost completely abolished if CBD was re-injected after previous administration. CBD reduced the Bezold-Jarisch reflex elicited by the 5-HT3 receptor agonist phenylbiguanide but not that evoked by the TRPV1 agonist capsaicin. In conscious rats, CBD did not affect cardiovascular parameters. In isolated left atria, CBD decreased contractile force. Conclusions: Cannabidiol (1) induces the Bezold-Jarisch reflex likely via TRPV1 receptors (which undergo tachyphylaxis) more markedly in SHR than in WKY; (2) inhibits the Bezold-Jarisch reflex induced by activation of 5-HT3 but not TRPV1 receptors; (3) has peripheral sympathomimetic, (4) vasodilatory, and (5) negative inotropic effects. The above properties of CBD should be taken under consideration when CBD is used for therapeutic purposes.
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Affiliation(s)
- Rafał Kossakowski
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Bialystok, Poland
| | - Eberhard Schlicker
- Department of Pharmacology and Toxicology, University of Bonn, Bonn, Germany
| | - Marek Toczek
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Bialystok, Poland
| | - Jolanta Weresa
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Bialystok, Poland
| | - Barbara Malinowska
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Bialystok, Poland
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19
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GABA B receptors in the hypothalamic paraventricular nucleus mediate β-adrenoceptor-induced elevations of plasma noradrenaline in rats. Eur J Pharmacol 2019; 848:88-95. [PMID: 30685430 DOI: 10.1016/j.ejphar.2019.01.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 01/15/2019] [Accepted: 01/18/2019] [Indexed: 11/21/2022]
Abstract
In the brain, various neurotransmitters such as noradrenaline and GABA regulate peripheral sympathetic functions. Previously, it has been reported that both β-adrenoceptor activation and GABAB receptor activation in the brain are involved in the elevation of plasma noradrenaline levels. However, it is unknown whether these pathways interact with each other. In the present study, we examined the relationship between the central actions of β-adrenoceptor activation and GABAB receptor activation with regard to plasma noradrenaline responses using urethane-anesthetized rats. Intracerebroventricular pretreatment with the GABAA receptor antagonist bicuculline did not affect the β-adrenoceptor agonist isoproterenol-induced elevation of plasma noradrenaline levels. In contrast, pretreatment with the GABAB receptor antagonist CGP 35348 suppressed the isoproterenol-induced elevation of noradrenaline levels. Intracerebroventricular pretreatment with the β-adrenoceptor antagonist propranolol did not alter the GABAB receptor agonist baclofen-induced elevation of plasma noradrenaline levels. We next examined the central effects of β-adrenoceptor activation on GABA release in the paraventricular hypothalamic nucleus (PVN), the major integrative center for sympathetic regulation in the brain. Intracerebroventricular administration of isoproterenol increased GABA content in PVN dialysates. In addition, baclofen microinjected unilaterally into the PVN resulted in elevated plasma levels of noradrenaline, but not adrenaline. Finally, unilateral blockade of GABAB receptors in the PVN suppressed the isoproterenol-induced elevation of plasma noradrenaline level. Our results suggest that activation of β-adrenoceptors in the brain, likely in the PVN, induces GABA release in the PVN, which in turn activates GABAB receptors in the PVN, leading to elevated plasma noradrenaline.
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20
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Mattucci S, Speidel J, Liu J, Ramer MS, Kwon BK, Tetzlaff W, Oxland TR. Development of a traumatic cervical dislocation spinal cord injury model with residual compression in the rat. J Neurosci Methods 2019; 322:58-70. [PMID: 30951755 DOI: 10.1016/j.jneumeth.2019.03.010] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Revised: 03/12/2019] [Accepted: 03/15/2019] [Indexed: 12/13/2022]
Abstract
BACKGROUND Preclinical spinal cord injury models do not represent the wide range of biomechanical factors seen in human injuries, such as spinal level, injury mechanism, velocity of spinal cord impact, and residual compression. These factors may be responsible for differences observed between experimental and clinical study results, especially related to the controversial issue of timing of surgical decompression. NEW METHOD Somatosensory Evoked Potentials were used to: a) characterize residual compression depths in a dislocation model, and b) evaluate the physiological effect of whether or not the spinal cord was decompressed following the initial injury, prior to the application of residual compression. Modifications to vertebral clamps and the development of a novel surgical frame allowed us to conduct surgical and injury procedures in a controlled manner without the risk of additional damage to the spinal cord. Behavioural outcomes were evaluated following varying dislocation displacements, in addition to the survivability of 4 h of residual compression following a traumatic injury. RESULTS Residual compression immediately following the initial dislocation demonstrated significantly different electrophysiological response compared to when the residual compression was delayed. COMPARISON WITH EXISTING METHOD There are currently no other residual compression models that utilize a dislocation injury mechanism. Many residual compression studies have demonstrated the effectiveness of early decompression, however the compression of the spinal cord is often not representative of clinical traumatic injuries. Preclinical studies typically model residual compression using a sustained force through quasi-static application, when human injuries often occur at high velocities, followed by a sustained displacement occlusion of the spinal canal. CONCLUSIONS This study has validated several novel procedural approaches and injury parameters, and provided critical details to implement in the development of a traumatic cervical dislocation SCI model with residual compression.
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Affiliation(s)
- Stephen Mattucci
- Orthopaedic and Injury Biomechanics Group, Departments of Orthopaedics and Mechanical Engineering, International Collaboration on Repair Discoveries, University of British Columbia, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
| | - Jason Speidel
- Orthopaedic and Injury Biomechanics Group, Departments of Orthopaedics and Mechanical Engineering, International Collaboration on Repair Discoveries, University of British Columbia, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
| | - Jie Liu
- International Collaboration on Repair Discoveries, University of British Columbia, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
| | - Matt S Ramer
- International Collaboration on Repair Discoveries, University of British Columbia, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
| | - Brian K Kwon
- International Collaboration on Repair Discoveries, University of British Columbia, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
| | - Wolfram Tetzlaff
- International Collaboration on Repair Discoveries, University of British Columbia, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
| | - Thomas R Oxland
- Orthopaedic and Injury Biomechanics Group, Departments of Orthopaedics and Mechanical Engineering, International Collaboration on Repair Discoveries, University of British Columbia, 818 West 10th Avenue, Vancouver, BC, V5Z 1M9, Canada.
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21
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Reynolds CA, O'Leary DS, Ly C, Smith SA, Minic Z. Development of a decerebrate model for investigating mechanisms mediating viscero-sympathetic reflexes in the spinalized rat. Am J Physiol Heart Circ Physiol 2019; 316:H1332-H1340. [PMID: 30875256 DOI: 10.1152/ajpheart.00724.2018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Autonomic dysreflexia (AD) often occurs in individuals living with spinal cord injury (SCI) and is characterized by uncontrolled hypertension in response to otherwise innocuous stimuli originating below the level of the spinal lesion. Visceral stimulation is a predominant cause of AD in humans and effectively replicates the phenotype in rodent models of SCI. Direct assessment of sympathetic responses to viscerosensory stimulation in spinalized animals is challenging and requires invasive surgical procedures necessitating the use of anesthesia. However, administration of anesthesia markedly affects viscerosensory reactivity, and the effects are exacerbated following spinal cord injury (SCI). Therefore, the major goal of the present study was to develop a decerebrate rodent preparation to facilitate quantification of sympathetic responses to visceral stimulation in the spinalized rat. Such a preparation enables the confounding effect of anesthesia to be eliminated. Sprague-Dawley rats were subjected to SCI at the fourth thoracic segment. Four weeks later, renal sympathetic nerve activity (RSNA) responses to visceral stimuli were quantified in urethane/chloralose-anesthetized and decerebrate preparations. Visceral stimulation was elicited via colorectal distension (CRD) for 1 min. In the decerebrate preparation, CRD produced dose-dependent increases in mean arterial pressure (MAP) and RSNA and dose-dependent decreases in heart rate (HR). These responses were significantly greater in magnitude among decerebrate animals when compared with urethane/chloralose-anesthetized controls and were markedly attenuated by the administration of urethane/chloralose anesthesia after decerebration. We conclude that the decerebrate preparation enables high-fidelity quantification of neuronal reactivity to visceral stimulation in spinalized rats. NEW & NOTEWORTHY In animal models commonly used to study spinal cord injury, quantification of sympathetic responses is particularly challenging due to the increased susceptibility of spinal reflex circuits to the anesthetic agents generally required for experimentation. This constitutes a major limitation to understanding the mechanisms mediating regionally specific neuronal responses to visceral activation in chronically spinalized animals. In the present study, we describe a spinalized, decerebrate rodent preparation that facilitates quantification of sympathetic reactivity in response to visceral stimuli following spinal cord injury. This preparation enables reliable and reproducible quantification of viscero-sympathetic reflex responses resembling those elicited in conscious animals and may provide added utility for preclinical evaluation of neuropharmacological agents for the management of autonomic dysreflexia.
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Affiliation(s)
- Christian A Reynolds
- Department of Emergency Medicine, Wayne State University School of Medicine , Detroit, Michigan.,Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
| | - Donal S O'Leary
- Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan.,Department of Physiology, Wayne State University School of Medicine , Detroit, Michigan
| | - Cheng Ly
- Department of Statistical Sciences and Operations Research, Virginia Commonwealth University , Richmond, Virginia
| | - Scott A Smith
- Department of Internal Medicine, University of Texas Southwestern Medical Center , Dallas, Texas.,Department of Health Care Sciences, University of Texas Southwestern Medical Center , Dallas, Texas
| | - Zeljka Minic
- Department of Emergency Medicine, Wayne State University School of Medicine , Detroit, Michigan.,Cardiovascular Research Institute, Wayne State University School of Medicine , Detroit, Michigan
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22
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Briyal S, Gandhakwala R, Khan M, Lavhale MS, Gulati A. Alterations in endothelin receptors following hemorrhage and resuscitation by centhaquin. Physiol Res 2018; 67:S199-S214. [PMID: 29947540 DOI: 10.33549/physiolres.933856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Endothelin-1 (ET-1) acts on ET(A) and ET(B) receptors and has been implicated in hemorrhagic shock (shock). We determined effect of shock and resuscitation by hypertonic saline (saline) or centhaquin on ET(A) and ET(B) receptor expression. Rats were anesthetized, a pressure catheter was placed in the left femoral artery; blood was withdrawn from the right femoral artery to bring mean arterial pressure (MAP) to 35 mm Hg for 30 min, resuscitation was performed and 90 min later sacrificed to collect samples for biochemical estimations. Resuscitation with centhaquin decreased blood lactate and increased MAP. Protein levels of ET(A) or ET(B) receptor were unaltered in the brain, heart, lung and liver following shock or resuscitation. In the abdominal aorta, shock produced an increase (140 %) in ET(A) expression which was attenuated by saline and centhaquin; ET(B) expression was unaltered following shock but was increased (79 %) by centhaquin. In renal medulla, ET(A) expression was unaltered following shock, but was decreased (-61 %) by centhaquin; shock produced a decrease (-34 %) in ET(B) expression which was completely attenuated by centhaquin and not saline. Shock induced changes in ET(A) and ET(B) receptors in the aorta and renal medulla are reversed by centhaquin and may be contributing to its efficacy.
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Affiliation(s)
- S Briyal
- Chicago College of Pharmacy, Midwestern University, Downers Grove, IL, USA.
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Mendonça MM, Santana JS, da Cruz KR, Ianzer D, Ghedini PC, Nalivaiko E, Fontes MAP, Ferreira RN, Pedrino GR, Colugnati DB, Xavier CH. Involvement of GABAergic and Adrenergic Neurotransmissions on Paraventricular Nucleus of Hypothalamus in the Control of Cardiac Function. Front Physiol 2018; 9:670. [PMID: 29915544 PMCID: PMC5994789 DOI: 10.3389/fphys.2018.00670] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Accepted: 05/14/2018] [Indexed: 11/13/2022] Open
Abstract
Sympathetic premotor neurons of the paraventricular hypothalamus (PVN) play a role in hemodynamics adjustments during changes in body fluid homeostasis. However, PVN contribution to the tonic control of cardiac function remains to be systematically studied. In this study, we assessed whether GABAergic and adrenergic synapses, known for being active in the PVN, are involved in the control of cardiac function. Adult male Wistar rats (250–350 g; n = 27) were anesthetized with urethane (1.2–1.4 g/kg i.p.) and underwent catheterization of femoral artery to record blood pressure and heart rate. The femoral vein was used to inject the vasoactive agents phenylephrine (10 μg/kg) and sodium nitroprusside (10 μg/kg) and to supplement anesthesia. The cardiac left ventricle was catheterized to record left ventricular pressure and its derivative. Craniotomy allowed for injections (100 nL) into the PVN of: muscimol (20 mM), bicuculline methiodide (0.4 mM), propranolol (10 mM), isoproterenol (100 μM), phentolamine (13 mM), phenylephrine (30 nM). We found that: (i) inhibition of PVN by muscimol, reduced arterial pressure, cardiac chronotropy and inotropy; (ii) disinhibition of PVN neurons by bicuculline evoked positive chronotropy and inotropy, and increase blood pressure; (iii) PVN alpha adrenergic receptors control cardiac chronotropy and inotropy; (iv) beta adrenergic receptors of the PVN do not influence cardiac function; (v) afterload does not contribute to the PVN-evoked inotropy. Our results indicate that the modulation of the activity of PVN neurons exerted by GABAergic and adrenergic mechanisms contribute to the control of cardiac function.
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Affiliation(s)
- Michelle M Mendonça
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Joice S Santana
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Kellen R da Cruz
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Danielle Ianzer
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Paulo C Ghedini
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Eugene Nalivaiko
- Neurocardiology Laboratory, School of Biomedical Sciences and Pharmacy, University of Newcastle, Callaghan, NSW, Australia
| | - Marco A P Fontes
- Department of Physiology and Biophysics, Institute of Biological Sciences, Federal University of Minas Gerais, Belo Horizonte, Brazil
| | - Reginaldo N Ferreira
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Gustavo R Pedrino
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Diego B Colugnati
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
| | - Carlos H Xavier
- Department of Physiological Sciences, Institute of Biological Sciences, Federal University of Goiás, Goiânia, Brazil
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Sasaki-Hamada S, Narusawa K, Nakamura R, Ishibashi H, Oka JI. Effects of centrally administered glucagon-like peptide-2 on blood pressure and barosensitive neurons in spontaneously hypertensive rats. Neuropeptides 2018; 69:66-75. [PMID: 29703428 DOI: 10.1016/j.npep.2018.04.007] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 02/25/2018] [Accepted: 04/15/2018] [Indexed: 02/07/2023]
Abstract
The central administration of glucagon-like peptide-2 (GLP-2) decreases blood pressure in rats. In the present study, we investigated the hypotensive effects of GLP-2 using spontaneously hypertensive rats (SHRs), an animal model of hypertension. The central administration of GLP-2 (0.6 μg) decreased mean arterial pressure (MAP) in SHRs (-24.1 ± 4.5%; P < 0.05), but not in normotensive Wistar-Kyoto (WKY) rats (-10.6 ± 7.4%; P > 0.05), whereas GLP-2 (6 μg) decreased MAP in WKY rats (-23.5 ± 4.2%; P < 0.05) and SHRs (-46.7 ± 11.6%; P < 0.01) under anesthesia with urethane and α-chloralose. Histological analyses revealed that the central administration of GLP-2 (6 μg) induced Fos immunoreactivity (Fos-IR) in the hypothalamic and medullary areas in WKY rats and SHRs. However, the distribution of Fos-IR in GABAergic neurons in the rostral ventrolateral medulla (RVLM) differed between WKY rats and SHRs. GLP-2 directly modulated the excitability of RVLM neurons in brainstem slices from SHRs, but not WKY rats. These results suggest that neuronal activity through the activation of GLP-2 receptors in the RVLM contributes to lowering blood pressure in SHRs.
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Affiliation(s)
- Sachie Sasaki-Hamada
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan; Department of Physiology, School of Allied Health Sciences, Kitasato University, Sagamihara 252-0373, Japan
| | - Koji Narusawa
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Ryuji Nakamura
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
| | - Hitoshi Ishibashi
- Department of Physiology, School of Allied Health Sciences, Kitasato University, Sagamihara 252-0373, Japan
| | - Jun-Ichiro Oka
- Laboratory of Pharmacology, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda, Chiba 278-8510, Japan.
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Colorectal and cardiovascular effects of [Lys 5,MeLeu 9,Nle 10]-NKA (4-10) in anesthetized macaques. Naunyn Schmiedebergs Arch Pharmacol 2018; 391:907-914. [PMID: 29858647 DOI: 10.1007/s00210-018-1520-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Accepted: 05/25/2018] [Indexed: 11/27/2022]
Abstract
The effects of the tachykinin NK2 receptor agonist LMN-NKA ([Lys5,MeLeu9,Nle10]-NKA(4-10)) on colorectal and arterial blood pressure were examined in anesthetized macaques. Intravenous (IV) administration of 1-100 μg/kg caused dose-related increases in colorectal pressure up to 120 mmHg above baseline, and area under the curve (AUC) up to 24,987 mmHg*s. This was accompanied at all doses by transient hypotension, with up to 26% reduction in mean arterial pressure (MAP) from baseline. Hypotension, but not the increase in colorectal pressure, was inhibited by a 10-min pretreatment with the NK1 receptor antagonist CP-99,994. In a pilot experiment using subcutaneous (SC) injection, a similar dose range of LMN-NKA (3-100 μg/kg) again appeared to increase colorectal pressure with a similar AUC (up to 18,546 mmHg*s) to that seen after IV injection, but lower peak amplitude (up to 49 mmHg). Unlike the effects of IV injection, hypotension was only present after the highest SC dose (100 μg/kg) in one of two animals. Pharmacokinetic analysis revealed markedly lower plasma exposures after SC compared with IV administration. Cmax was 39.6 versus 1070 ng/mL, and AUCinf was 627 versus 2090 ng/mL*min, respectively. These findings are consistent with previous observations in anesthetized dogs and indicate that the prokinetic effects of LMN-NKA may be achieved without hypotension using a route of administration that avoids unnecessarily high plasma exposures.
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Lee C, Jones TA. Effects of Ketamine Compared with Urethane Anesthesia on Vestibular Sensory Evoked Potentials and Systemic Physiology in Mice. JOURNAL OF THE AMERICAN ASSOCIATION FOR LABORATORY ANIMAL SCIENCE : JAALAS 2018; 57:268-277. [PMID: 29784077 PMCID: PMC5966234 DOI: 10.30802/aalas-jaalas-17-000131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Revised: 10/19/2017] [Accepted: 01/05/2018] [Indexed: 06/08/2023]
Abstract
The injectable anesthetic mixture ketamine-xylazine is commonly used for electrophysiologic experiments in laboratory animals, especially rodents. General anesthesia can induce significant changes in systemic physiology, including those that compromise neural function, thus introducing research confounds. The extent of such concerns varies by agent. Here in mice, we compared the effects of ketamine-xylazine and urethane-xylazine anesthesia on systemic physiologic parameters and the vestibular sensory evoked potential (VsEP), a tool used commonly to assess peripheral vestibular function. Urethane-xylazine anesthesia provided longer anesthesia, prolonged survival times, and less compromised respiratory and cardiovascular function, compared with ketamine-xylazine. In the absence of countermeasures, mice anesthetized with either ketamine-xylazine or urethane-xylazine showed evidence of hypoxemia and fluctuations in brain temperature, heart rate, respiration rate, and VsEP response latency. The levels of hypoxemia had no effect on VsEP response parameters over the period of study (2 to 5 h). Hypoxemia was effectively countered with O2 supplementation, which stabilized respiratory rates and improved mean survival times by 160% in mice anesthetized with ketamine-xylazine. Monitoring and controlling brain temperature reduced variation in VsEP latency. VsEP thresholds, latencies, and amplitudes did not differ between mice under ketamine-xylazine compared with urethane-xylazine when the brain temperature was held at the same set point. These findings demonstrate that urethane-xylazine provides improved systemic physiologic conditions during anesthesia in mice and may be substituted for ketamine-xylazine in studies using the VsEP to evaluate peripheral vestibular function. Such advantages may prove useful to research in other neuroscience areas and might reduce the number of animals used to achieve adequate sample sizes.
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Affiliation(s)
- Choongheon Lee
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska, Department of Otolaryngology, Washington University School of Medicine, St Louis, Missouri
| | - Timothy A Jones
- Department of Special Education and Communication Disorders, University of Nebraska-Lincoln, Lincoln, Nebraska;,
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27
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Bezdudnaya T, Hormigo KM, Marchenko V, Lane MA. Spontaneous respiratory plasticity following unilateral high cervical spinal cord injury in behaving rats. Exp Neurol 2018; 305:56-65. [PMID: 29596845 DOI: 10.1016/j.expneurol.2018.03.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2017] [Revised: 01/23/2018] [Accepted: 03/23/2018] [Indexed: 01/25/2023]
Abstract
Unilateral cervical C2 hemisection (C2Hx) is a classic model of spinal cord injury (SCI) for studying respiratory dysfunction and plasticity. However, most previous studies were performed under anesthesia, which significantly alters respiratory network. Therefore, the goal of this work was to assess spontaneous diaphragm recovery post-C2Hx in awake, freely behaving animals. Adult rats were chronically implanted with diaphragm EMG electrodes and recorded during 8 weeks post-C2Hx. Our results reveal that ipsilateral diaphragm activity partially recovers within days post-injury and reaches pre-injury amplitude in a few weeks. However, the full extent of spontaneous ipsilateral recovery is significantly attenuated by anesthesia (ketamine/xylazine, isoflurane, and urethane). This suggests that the observed recovery may be attributed in part to activation of NMDA receptors which are suppressed by anesthesia. Despite spontaneous recovery in awake animals, ipsilateral hemidiaphragm dysfunction still persists: i) Inspiratory bursts during basal (slow) breathing exhibit an altered pattern, ii) the amplitude of sighs - or augmented breaths - is significantly decreased, and iii) the injured hemidiaphragm exhibits spontaneous events of hyperexcitation. The results from this study offer an under-appreciated insight into spontaneous diaphragm activity and recovery following high cervical spinal cord injury in awake animals.
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Affiliation(s)
- Tatiana Bezdudnaya
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, 2900 W Queen Lane, Philadelphia, PA 19129, USA.
| | - Kristiina M Hormigo
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, 2900 W Queen Lane, Philadelphia, PA 19129, USA
| | - Vitaliy Marchenko
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, 2900 W Queen Lane, Philadelphia, PA 19129, USA
| | - Michael A Lane
- Department of Neurobiology and Anatomy, College of Medicine, Drexel University, 2900 W Queen Lane, Philadelphia, PA 19129, USA
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Pérez-Cervera L, Caramés JM, Fernández-Mollá LM, Moreno A, Fernández B, Pérez-Montoyo E, Moratal D, Canals S, Pacheco-Torres J. Mapping Functional Connectivity in the Rodent Brain Using Electric-Stimulation fMRI. Methods Mol Biol 2018; 1718:117-134. [PMID: 29341006 DOI: 10.1007/978-1-4939-7531-0_8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Since its discovery in the early 90s, BOLD signal-based functional Magnetic Resonance Imaging (fMRI) has become a fundamental technique for the study of brain activity in basic and clinical research. Functional MRI signals provide an indirect but robust and quantitative readout of brain activity through the tight coupling between cerebral blood flow and neuronal activation, the so-called neurovascular coupling. Combined with experimental techniques only available in animal models, such as intracerebral micro-stimulation, optogenetics or pharmacogenetics, provides a powerful framework to investigate the impact of specific circuit manipulations on overall brain dynamics. The purpose of this chapter is to provide a comprehensive protocol to measure brain activity using fMRI with intracerebral electric micro-stimulation in murine models. Preclinical research (especially in rodents) opens the door to very sophisticated and informative experiments, but at the same time imposes important constrains (i.e., anesthetics, translatability), some of which will be addressed here.
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Affiliation(s)
- Laura Pérez-Cervera
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Spain
| | - José María Caramés
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Spain
| | | | - Andrea Moreno
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Spain
- Center for Biomaterials and Tissue Engineering, Universitat Politècnica de València, Valencia, 46022, Spain
| | - Begoña Fernández
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Spain
| | - Elena Pérez-Montoyo
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Spain
| | - David Moratal
- Center for Biomaterials and Tissue Engineering, Universitat Politècnica de València, Valencia, 46022, Spain
| | - Santiago Canals
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Spain
| | - Jesús Pacheco-Torres
- Instituto de Neurociencias, Consejo Superior de Investigaciones Científicas, Universidad Miguel Hernández, Sant Joan d'Alacant, 03550, Spain.
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29
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Ma J, Ma Y, Dong B, Bandet MV, Shuaib A, Winship IR. Prevention of the collapse of pial collaterals by remote ischemic perconditioning during acute ischemic stroke. J Cereb Blood Flow Metab 2017; 37:3001-3014. [PMID: 27909265 PMCID: PMC5536804 DOI: 10.1177/0271678x16680636] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 09/23/2016] [Accepted: 10/30/2016] [Indexed: 02/05/2023]
Abstract
Collateral circulation is a key variable determining prognosis and response to recanalization therapy during acute ischemic stroke. Remote ischemic perconditioning (RIPerC) involves inducing peripheral ischemia (typically in the limbs) during stroke and may reduce perfusion deficits and brain damage due to cerebral ischemia. In this study, we directly investigated pial collateral flow augmentation due to RIPerC during distal middle cerebral artery occlusion (MCAo) in rats. Blood flow through pial collaterals between the anterior cerebral artery (ACA) and the MCA was assessed in male Sprague Dawley rats using in vivo laser speckle contrast imaging (LSCI) and two photon laser scanning microscopy (TPLSM) during distal MCAo. LSCI and TPLSM revealed that RIPerC augmented collateral flow into distal MCA segments. Notably, while control rats exhibited an initial dilation followed by a progressive narrowing of pial arterioles 60 to 150-min post-MCAo (constricting to 80-90% of post-MCAo peak diameter), this constriction was prevented or reversed by RIPerC (such that vessel diameters increased to 105-110% of post-MCAo, pre-RIPerC diameter). RIPerC significantly reduced early ischemic damage measured 6 h after stroke onset. Thus, prevention of collateral collapse via RIPerC is neuroprotective and may facilitate other protective or recanalization therapies by improving blood flow in penumbral tissue.
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Affiliation(s)
- Junqiang Ma
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- The First Affiliated Hospital, Shantou University Medical College, Shantou, China
| | - Yonglie Ma
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Bin Dong
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Mischa V Bandet
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
| | - Ashfaq Shuaib
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Department of Medicine, Division of Neurology, University of Alberta, Edmonton, AB, Canada
| | - Ian R Winship
- Neuroscience and Mental Health Institute, University of Alberta, Edmonton, AB, Canada
- Neurochemical Research Unit, Department of Psychiatry, University of Alberta, Edmonton, AB, Canada
- Ian R Winship, 12-127 Clinical Sciences Building, Edmonton, AB T6G 2R3, Canada.
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Donnelly WT, Xia L, Bartlett D, Leiter JC. Activation of serotonergic neurons in the medullary caudal raphe shortens the laryngeal chemoreflex in anaesthetized neonatal rats. Exp Physiol 2017; 102:1007-1018. [PMID: 28675564 DOI: 10.1113/ep086082] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Accepted: 05/25/2017] [Indexed: 12/29/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does activation of serotonergic neurons in the caudal medullary raphe, some of which project to the nucleus of the solitary tract, shorten the laryngeal chemoreflex? What is the main finding and its importance? We found that serotonin originating from neurons in the caudal raphe acts through a 5-HT3 receptor located in the nucleus of the solitary tract to terminate reflex apnoea. Failure or deficiency of this arousal-related process is likely to be relevant to the pathogenesis of sudden infant death syndrome. Failure to terminate apnoea and arouse is likely to contribute to sudden infant death syndrome (SIDS). Serotonin is deficient in the brainstems of babies who have died of SIDS. We tested the hypothesis that activation of serotoninergic neurons in the caudal medullary raphe, some of which project to the nucleus of the solitary tract (NTS), would shorten the laryngeal chemoreflex (LCR). We studied anaesthetized neonatal rat pups between postnatal days 9 and 17. We injected 5-40 μl of water into the larynx to elicit the LCR and measured the duration of respiratory disruption. Microinjection of 50 nl of 100 μm AMPA into the caudal medullary raphe shortened the apnoeas (P < 0.001) and respiratory inhibition (P < 0.005) associated with the LCR. When 50 nl of 30 mm ondansetron, a 5-HT3 antagonist, was microinjected bilaterally into the NTS, AMPA microinjected into the caudal raphe no longer shortened the LCR. After bilateral microinjection of vehicle into the NTS, AMPA microinjection into the caudal raphe significantly shortened the LCR. AMPA, a glutamate receptor agonist, may activate many neurons within the caudal raphe, but blocking the 5-HT3 receptor-dependent responses in the NTS prevented the shortening of the LCR associated with AMPA microinjections into the caudal raphe. Thus, serotonin originating from neurons in the caudal raphe acts through a 5-HT3 receptor located in the NTS to terminate or shorten the LCR. Serotonin is deficient in the brainstems of babies who have died of SIDS, and deficient serotonergic termination of apnoea is likely to be relevant to the pathogenesis of SIDS.
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Affiliation(s)
- William T Donnelly
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA
| | - Luxi Xia
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA
| | - Donald Bartlett
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA
| | - J C Leiter
- Department of Molecular and Systems Biology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA
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31
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Donnelly WT, Bartlett D, Leiter JC. Serotonin in the solitary tract nucleus shortens the laryngeal chemoreflex in anaesthetized neonatal rats. Exp Physiol 2016; 101:946-61. [PMID: 27121960 DOI: 10.1113/ep085716] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 04/08/2016] [Indexed: 11/08/2022]
Abstract
What is the central question of this study? Failure to terminate apnoea and arouse is likely to contribute to sudden infant death syndrome (SIDS). Serotonin is deficient in the brainstems of babies who died of SIDS. Therefore, we tested the hypothesis that serotonin in the nucleus of the solitary tract (NTS) would shorten reflex apnoea. What is the main finding and its importance? Serotonin microinjected into the NTS shortened the apnoea and respiratory inhibition associated with the laryngeal chemoreflex. Moreover, this effect was achieved through a 5-HT3 receptor. This is a new insight that is likely to be relevant to the pathogenesis of SIDS. The laryngeal chemoreflex (LCR), an airway-protective reflex that causes apnoea and bradycardia, has long been suspected as an initiating event in the sudden infant death syndrome. Serotonin (5-HT) and 5-HT receptors may be deficient in the brainstems of babies who die of sudden infant death syndrome, and 5-HT seems to be important in terminating apnoeas directly or in causing arousals or as part of the process of autoresuscitation. We hypothesized that 5-HT in the brainstem would limit the duration of the LCR. We studied anaesthetized rat pups between 7 and 21 days of age and made microinjections into the cisterna magna or into the nucleus of the solitary tract (NTS). Focal, bilateral microinjections of 5-HT into the caudal NTS significantly shortened the LCR. The 5-HT1a receptor antagonist, WAY 100635, did not affect the LCR consistently, nor did a 5-HT2 receptor antagonist, ketanserin, alter the duration of the LCR. The 5-HT3 specific agonist, 1-(3-chlorophenyl)-biguanide, microinjected bilaterally into the caudal NTS significantly shortened the LCR. Thus, endogenous 5-HT released within the NTS may curtail the respiratory depression that is part of the LCR, and serotonergic shortening of the LCR may be attributed to activation of 5-HT3 receptors within the NTS. 5-HT3 receptors are expressed presynaptically on C fibre afferents of the superior laryngeal nerve, and serotonergic shortening of the LCR may be mediated presynaptically by enhanced activation of inhibitory interneurons within the NTS.
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Affiliation(s)
- William T Donnelly
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH, 03756, USA
| | - Donald Bartlett
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH, 03756, USA
| | - J C Leiter
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, NH, 03756, USA
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32
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Slack R, Boorman L, Patel P, Harris S, Bruyns-Haylett M, Kennerley A, Jones M, Berwick J. A novel method for classifying cortical state to identify the accompanying changes in cerebral hemodynamics. J Neurosci Methods 2016; 267:21-34. [PMID: 27063501 PMCID: PMC4896992 DOI: 10.1016/j.jneumeth.2016.04.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2015] [Revised: 03/29/2016] [Accepted: 04/06/2016] [Indexed: 11/27/2022]
Abstract
We classified brain state using a vector-based categorisation of neural frequencies. Changes in cerebral blood volume (CBV) were observed when brain state altered. During these state alterations, changes in blood oxygenation were also found. State dependent haemodynamic changes could affect blood based brain imaging.
Background Many brain imaging techniques interpret the haemodynamic response as an indirect indicator of underlying neural activity. However, a challenge when interpreting this blood based signal is how changes in brain state may affect both baseline and stimulus evoked haemodynamics. New method We developed an Automatic Brain State Classifier (ABSC), validated on data from anaesthetised rodents. It uses vectorised information obtained from the windowed spectral frequency power of the Local Field Potential. Current state is then classified by comparing this vectorised information against that calculated from state specific training datasets. Results The ABSC identified two user defined brain states (synchronised and desynchronised), with high accuracy (∼90%). Baseline haemodynamics were found to be significantly different in the two identified states. During state defined periods of elevated baseline haemodynamics we found significant decreases in evoked haemodynamic responses to somatosensory stimuli. Comparison to existing methods State classification – The ABSC (∼90%) demonstrated greater accuracy than clustering (∼66%) or ‘power threshold’ (∼64%) methods of comparison. Haemodynamic averaging – Our novel approach of selectively averaging stimulus evoked haemodynamic trials by brain state yields higher quality data than creating a single average from all trials. Conclusions The ABSC can account for some of the commonly observed trial-to-trial variability in haemodynamic responses which arises from changes in cortical state. This variability might otherwise be incorrectly attributed to alternative interpretations. A greater understanding of the effects of cortical state on haemodynamic changes could be used to inform techniques such as general linear modelling (GLM), commonly used in fMRI.
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Affiliation(s)
- R Slack
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - L Boorman
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - P Patel
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - S Harris
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - M Bruyns-Haylett
- Department of Systems Engineering, University of Reading, Whiteknights, Reading RG6 6AY, United Kingdom.
| | - A Kennerley
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - M Jones
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
| | - J Berwick
- Department of Psychology, University of Sheffield, Western Bank, Sheffield S10 2TN, United Kingdom.
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Judenherc-Haouzi A, Zhang XQ, Sonobe T, Song J, Rannals MD, Wang J, Tubbs N, Cheung JY, Haouzi P. Methylene blue counteracts H2S toxicity-induced cardiac depression by restoring L-type Ca channel activity. Am J Physiol Regul Integr Comp Physiol 2016; 310:R1030-44. [PMID: 26962024 DOI: 10.1152/ajpregu.00527.2015] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 03/08/2016] [Indexed: 11/22/2022]
Abstract
We have previously reported that methylene blue (MB) can counteract hydrogen sulfide (H2S) intoxication-induced circulatory failure. Because of the multifarious effects of high concentrations of H2S on cardiac function, as well as the numerous properties of MB, the nature of this interaction, if any, remains uncertain. The aim of this study was to clarify 1) the effects of MB on H2S-induced cardiac toxicity and 2) whether L-type Ca(2+) channels, one of the targets of H2S, could transduce some of the counteracting effects of MB. In sedated rats, H2S infused at a rate that would be lethal within 5 min (24 μM·kg(-1)·min(-1)), produced a rapid fall in left ventricle ejection fraction, determined by echocardiography, leading to a pulseless electrical activity. Blood concentrations of gaseous H2S reached 7.09 ± 3.53 μM when cardiac contractility started to decrease. Two to three injections of MB (4 mg/kg) transiently restored cardiac contractility, blood pressure, and V̇o2, allowing the animals to stay alive until the end of H2S infusion. MB also delayed PEA by several minutes following H2S-induced coma and shock in unsedated rats. Applying a solution containing lethal levels of H2S (100 μM) on isolated mouse cardiomyocytes significantly reduced cell contractility, intracellular calcium concentration ([Ca(2+)]i) transient amplitudes, and L-type Ca(2+) currents (ICa) within 3 min of exposure. MB (20 mg/l) restored the cardiomyocyte function, ([Ca(2+)]i) transient, and ICa The present results offer a new approach for counteracting H2S toxicity and potentially other conditions associated with acute inhibition of L-type Ca(2+) channels.
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Affiliation(s)
- Annick Judenherc-Haouzi
- Heart and Vascular Institute, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania;
| | - Xue-Qian Zhang
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - Takashi Sonobe
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania
| | - Jianliang Song
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - Matthew D Rannals
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania
| | - JuFang Wang
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; and
| | - Nicole Tubbs
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania
| | - Joseph Y Cheung
- Center of Translational Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania; and Department of Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - Philippe Haouzi
- Division of Pulmonary and Critical Care Medicine, Department of Medicine, Pennsylvania State University, College of Medicine, Hershey, Pennsylvania
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Umbarkar P, Singh S, Arkat S, Bodhankar SL, Lohidasan S, Sitasawad SL. Monoamine oxidase-A is an important source of oxidative stress and promotes cardiac dysfunction, apoptosis, and fibrosis in diabetic cardiomyopathy. Free Radic Biol Med 2015; 87:263-73. [PMID: 26122707 DOI: 10.1016/j.freeradbiomed.2015.06.025] [Citation(s) in RCA: 68] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Revised: 05/22/2015] [Accepted: 06/09/2015] [Indexed: 12/23/2022]
Abstract
Oxidative stress is closely associated with the pathophysiology of diabetic cardiomyopathy (DCM). The mitochondrial flavoenzyme monoamine oxidase A (MAO-A) is an important source of oxidative stress in the myocardium. We sought to determine whether MAO-A plays a major role in modulating DCM. Diabetes was induced in Wistar rats by single intraperitoneal injection of streptozotocin (STZ). To investigate the role of MAO-A in the development of pathophysiological features of DCM, hyperglycemic and age-matched control rats were treated with or without the MAO-A-specific inhibitor clorgyline (CLG) at 1 mg/kg/day for 8 weeks. Diabetes upregulated MAO-A activity; elevated markers of oxidative stress such as cardiac lipid peroxidation, superoxide dismutase activity, and UCP3 protein expression; enhanced apoptotic cell death; and increased fibrosis. All these parameters were significantly attenuated by CLG treatment. In addition, treatment with CLG substantially prevented diabetes-induced cardiac contractile dysfunction as evidenced by decreased QRS, QT, and corrected QT intervals, measured by ECG, and LV systolic and LV end-diastolic pressure measured by microtip pressure transducer. These beneficial effects of CLG were seen despite the persistent hyperglycemic and hyperlipidemic environments in STZ-induced experimental diabetes. In summary, this study provides strong evidence that MAO-A is an important source of oxidative stress in the heart and that MAO-A-derived reactive oxygen species contribute to DCM.
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Affiliation(s)
- Prachi Umbarkar
- National Centre for Cell Science, NCCS Complex, S.P. Pune University, Ganeshkhind, Pune 411007, Maharashtra, India
| | - Sarojini Singh
- National Centre for Cell Science, NCCS Complex, S.P. Pune University, Ganeshkhind, Pune 411007, Maharashtra, India
| | - Silpa Arkat
- National Centre for Cell Science, NCCS Complex, S.P. Pune University, Ganeshkhind, Pune 411007, Maharashtra, India
| | - S L Bodhankar
- Department of Pharmacology, Poona College of Pharmacy, Bharati Vidyapeeth Deemed University, Erandwane, Pune, India
| | - Sathiyanarayanan Lohidasan
- Department of Pharmaceutical Chemistry, Poona College of Pharmacy, Bharati Vidyapeeth Deemed University, Erandwane, Pune, India
| | - Sandhya L Sitasawad
- National Centre for Cell Science, NCCS Complex, S.P. Pune University, Ganeshkhind, Pune 411007, Maharashtra, India.
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Ideal target arterial pressure after control of bleeding in a rabbit model of severe traumatic hemorrhagic shock: results from volume loading-based fluid resuscitation. J Surg Res 2015; 196:358-67. [PMID: 25791824 DOI: 10.1016/j.jss.2015.02.052] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Revised: 02/11/2015] [Accepted: 02/20/2015] [Indexed: 11/23/2022]
Abstract
BACKGROUND Previously reported ideal target mean arterial pressure (MAP) after control of bleeding in traumatic hemorrhagic shock (THS) requires further verification in more clinically related models. The authors explored this issue via gradient volume loading without vasopressor therapy. As certain volume loading can induce secretion of atrial natriuretic peptide (ANP), which has been shown to be protective, the authors also observed its potential role. MATERIALS AND METHODS Fifty male New Zealand rabbits were submitted to 1.5 h of uncontrolled THS (with another eight rabbits assigned to the sham group). After bleeding control, treated rabbits were randomly (n = 10, respectively) resuscitated with blood and Ringer lactate (1:2) to achieve target MAP of 50, 60, 70, 80, and 90 mm Hg within 1 h. During the following 2 h, they were resuscitated toward baseline MAP. Rabbits were observed until 7 h. RESULTS After resuscitation, infused fluid was lower and oxidative stress injury was milder in the 70 mm Hg group. Fluid volume loaded during the initial hour after hemostasis was negatively correlated with pH, oxygen saturation, and base excess at the end of resuscitation. It also correlated positively with proinflammatory responses in bronchoalveolar lavage fluid at 7 h and 7-h mortality. Moreover, after volume loading, the 80 mm Hg group showed significantly increased serum ANP level, which correlated with the expression of Akt protein in the jejunum at 7 h. CONCLUSIONS In rabbits the ideal target MAP during the initial resuscitation of severe THS after hemostasis was 70 mm Hg. ANP may have a critical role in gut protection.
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Lucking EF, O'Halloran KD, Jones JFX. Increased cardiac output contributes to the development of chronic intermittent hypoxia-induced hypertension. Exp Physiol 2014; 99:1312-24. [DOI: 10.1113/expphysiol.2014.080556] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Eric F. Lucking
- UCD School of Medicine and Medical Science; University College Dublin; Dublin 4 Ireland
| | - Ken D. O'Halloran
- Department of Physiology; School of Medicine; University College Cork; Cork Ireland
| | - James F. X. Jones
- UCD School of Medicine and Medical Science; University College Dublin; Dublin 4 Ireland
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Grandjean J, Schroeter A, Batata I, Rudin M. Optimization of anesthesia protocol for resting-state fMRI in mice based on differential effects of anesthetics on functional connectivity patterns. Neuroimage 2014; 102 Pt 2:838-47. [PMID: 25175535 DOI: 10.1016/j.neuroimage.2014.08.043] [Citation(s) in RCA: 203] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 08/13/2014] [Accepted: 08/21/2014] [Indexed: 10/24/2022] Open
Abstract
Resting state-fMRI (rs-fMRI) in mice allows studying mechanisms underlying functional connectivity (FC) as well as alterations of FC occurring in murine models of neurological diseases. Mouse fMRI experiments are typically carried out under anesthesia to minimize animal movement and potential distress during examination. Yet, anesthesia inevitably affects FC patterns. Such effects have to be understood for proper interpretation of data. We have compared the influence of four commonly used anesthetics on rs-fMRI. Rs-fMRI data acquired under isoflurane, propofol, and urethane presented similar patterns when accounting for anesthesia depth. FC maps displayed bilateral correlation with respect to cortical seeds, but no significant inter-hemispheric striatal connectivity. In contrast, for medetomidine, we detected bilateral striatal but compromised inter-hemispheric cortical connectivity. The spatiotemporal patterns of the rs-fMRI signal have been rationalized considering anesthesia depth and pharmacodynamic properties of the anesthetics. Our results bridge the results from different studies from the burgeoning field of mouse rs-fMRI and offer a framework for understanding the influences of anesthetics on FC patterns. Utilizing this information, we suggest the combined use of medetomidine and isoflurane representing the two proposed classes of anesthetics; the combination of low doses of the two anesthetics retained strong correlations both within cortical and subcortical structures, without the potential seizure-inducing effects of medetomidine, rendering this regimen an attractive anesthesia for rs-fMRI in mice.
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Affiliation(s)
- Joanes Grandjean
- Institute for Biomedical Engineering, University and ETH Zurich, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, Winterthurer-Str. 190, 8057 Zurich, Switzerland
| | - Aileen Schroeter
- Institute for Biomedical Engineering, University and ETH Zurich, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, Winterthurer-Str. 190, 8057 Zurich, Switzerland
| | - Imene Batata
- Institute for Biomedical Engineering, University and ETH Zurich, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland
| | - Markus Rudin
- Institute for Biomedical Engineering, University and ETH Zurich, Wolfgang-Pauli-Str. 27, 8093 Zurich, Switzerland; Neuroscience Center Zurich, University and ETH Zurich, Winterthurer-Str. 190, 8057 Zurich, Switzerland; Institute of Pharmacology and Toxicology, University of Zurich, Winterthurer-Str. 190, 8057 Zurich, Switzerland.
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Brožíčková C, Otáhal J. Effect of an inhibitor of neuronal nitric oxide synthase 7-nitroindazole on cerebral hemodynamic response and brain excitability in urethane-anesthetized rats. Physiol Res 2014; 62:S57-66. [PMID: 24329704 DOI: 10.33549/physiolres.932564] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
The role of neuronal nitric oxide synthase (nNOS) in the pathophysiology of epilepsy and seizures remains disputable. One of the reasons why results from the acute in vivo studies display controversies might be the effect on the regulation of cerebral blood flow (CBF) during pharmacologically induced alterations of NO system. We examined neurovascular coupling in the rat sensorimotor cortex in response to transcallosal stimulation under nNOS inhibition by 7-nitroindazole (7-NI). Adult Wistar rats were anesthetized with urethane and epidural silver EEG electrodes were implanted over sensorimotor cortices. Regional CBF was measured by Laser Doppler Flowmetry (LDF). We catheterized a common carotid artery to measure arterial blood pressure (BP). 7-NI did not significantly affect blood pressure and heart rate. Electrophysiological recordings of evoked potentials (EPs) revealed no effect on their amplitude, rhythmic potentiation or depression of EPs. Transcallosal stimulation of the contralateral cortex induced a frequency dependent rise in CBF. Although 7-NI did not significantly affect basal CBF and cortical excitability, hemodynamic responses to the transcallosal stimulation were diminished implicating a role of nNOS in neurovascular coupling. Urethane anesthesia is suitable for future epileptological experiments. Our findings demonstrate that NO contributes to the hemodynamic response during brain activation.
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Affiliation(s)
- C Brožíčková
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
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Specificity of stimulus-evoked fMRI responses in the mouse: the influence of systemic physiological changes associated with innocuous stimulation under four different anesthetics. Neuroimage 2014; 94:372-384. [PMID: 24495809 DOI: 10.1016/j.neuroimage.2014.01.046] [Citation(s) in RCA: 92] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 01/09/2014] [Accepted: 01/24/2014] [Indexed: 02/07/2023] Open
Abstract
Functional magnetic resonance (fMRI) in mice has become an attractive tool for mechanistic studies, for characterizing models of human disease, and for evaluation of novel therapies. Yet, controlling the physiological state of mice is challenging, but nevertheless important as changes in cardiovascular parameters might affect the hemodynamic readout which constitutes the basics of the fMRI signal. In contrast to rats, fMRI studies in mice report less robust brain activation of rather widespread character to innocuous sensory stimulation. Anesthesia is known to influence the characteristics of the fMRI signal. To evaluate modulatory effects imposed by the anesthesia on stimulus-evoked fMRI responses, we compared blood oxygenation level dependent (BOLD) and cerebral blood volume (CBV) signal changes to electrical hindpaw stimulation using the four commonly used anesthetics isoflurane, medetomidine, propofol and urethane. fMRI measurements were complemented by assessing systemic physiological parameters throughout the experiment. Unilateral stimulation of the hindpaw elicited widespread fMRI responses in the mouse brain displaying a bilateral pattern irrespective of the anesthetic used. Analysis of magnitude and temporal profile of BOLD and CBV signals indicated anesthesia-specific modulation of cerebral hemodynamic responses and differences observed for the four anesthetics could be largely explained by their known effects on animal physiology. Strikingly, independent of the anesthetic used our results reveal that fMRI responses are influenced by stimulus-induced cardiovascular changes, which indicate an arousal response, even to innocuous stimulation. This may mask specific fMRI signal associated to the stimulus. Hence, studying the processing of peripheral input in mice using fMRI techniques constitutes a major challenge and adapted paradigms and/or alternative fMRI readouts should also be considered when studying sensory processing in mice.
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Cardiac electrographic and morphological changes following status epilepticus: Effect of clonidine. Seizure 2014; 23:55-61. [DOI: 10.1016/j.seizure.2013.09.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/17/2013] [Accepted: 09/18/2013] [Indexed: 11/17/2022] Open
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The influence of pemirolast on autonomic imbalance in rat cystitis model. Open Med (Wars) 2013. [DOI: 10.2478/s11536-013-0217-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractCyclophosphamide (CP) treatment is associated with the risk of haemorrhagic cystitis (HC). Moreover, CP-induced HC is complicated by autonomic nervous system (ANS) dysfunction. Pemirolast is thought to be a mast cell stabiliser that inhibits the release of many inflammatory mediators and sensory neuropeptides, and thus, it may be considered a potential chemoprotective HC agent. The aim of the study was to indirectly estimate the effect of pemirolast in experimental HC by measuring ANS activity with the heart rate variability (HRV) method. In CP-treated rats, we found a decreasing trend of overall autonomic activity, together with an imbalance between the main components, and a dominant very low frequency (VLF) power component. Pemirolast treatment did not improve the total HRV power value or the main non-normalized HRV components. Moreover, CP-HC animals treated with pemirolast displayed a different disproportion of normalized spectral components as compared to both control and CP-HC animals without pemirolast treatment, with the balance between normalized low frequency (nLF) and normalized high frequency (nHF) shifted towards nLF. This finding, together with a relatively high VLF tension, indicates that the pemirolast treatment resulted in high sympathetic activity that may contribute to HC exacerbation; thus, this agent seems to be ineffective in CP-induced HC.
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Dobrek L, Thor P. Heart rate variability in overactive bladder experimental model. Arch Med Sci 2013; 9:930-5. [PMID: 24273581 PMCID: PMC3832811 DOI: 10.5114/aoms.2012.30946] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 11/14/2011] [Accepted: 02/02/2012] [Indexed: 12/03/2022] Open
Abstract
INTRODUCTION TWO MAIN PATHOPHYSIOLOGICAL CONCEPTS OF OVERACTIVE BLADDER (OAB) ARE POSTULATED: the neurogenic and myogenic theories. Autonomic nervous system (ANS) dysfunction is also involved in OAB pathophysiology. The purpose of our study was to estimate ANS activity by heart rate variability (HRV) assessment in two OAB experimental models evoked by cyclophosphamide administration: acute (AOAB) and chronic (COAB) overactive ones. MATERIAL AND METHODS In the AOAB model, an i.p. dose of cyclophosphamide was administered (200 mg/kg body weight) while the COAB model received 4 times the i.p. administration of cyclophosphamide (75 mg/kg body weight). In each subject, after urethane anaesthesia (1.2 g/kg body weight), 20-minute ECG recordings (PowerLab) were performed with subsequent HRV analysis. RESULTS Most of the differences in time domain analysis parameters were insignificant, except those concerning SDNN and rMSSD (p < 0.05). In frequency analysis, a power decrease of all standard spectral components was revealed in both OAB groups. In AOAB, TP (1.43 ±1.21 vs. 7.92 ±6.22 in control; p < 0.05) and VLF (0.95 ±1.08 vs. 6.97 ±5.99 in control; p < 0.05) showed significant power decrease, whereas the COAB group was mostly characterized by LF (0.09 ±0.15 vs. 0.34 ±0.33 in control; p < 0.05) and HF (0.25 ±0.29 vs. 0.60 ±0.41 in control; p < 0.05) decrease. CONCLUSIONS The ANS disturbances, found as standard spectral parameter abnormalities, were demonstrated in both AOAB and COAB. When this finding is analysed, together with the lack of statistically significant differences in normalized nLF and nHF powers, the VLF changes seem to play an essential role, probably reflecting the progression in bladder inflammatory changes.
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Affiliation(s)
- Lukasz Dobrek
- Pathophysiology Department, Jagiellonian University, Medical College, Cracow, Poland
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Breathing and brain state: Urethane anesthesia as a model for natural sleep. Respir Physiol Neurobiol 2013; 188:324-32. [DOI: 10.1016/j.resp.2013.05.035] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/06/2013] [Accepted: 05/28/2013] [Indexed: 01/26/2023]
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Gulati A, Zhang Z, Murphy A, Lavhale MS. Efficacy of centhaquin as a small volume resuscitative agent in severely hemorrhaged rats. Am J Emerg Med 2013; 31:1315-21. [PMID: 23871440 DOI: 10.1016/j.ajem.2013.05.032] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 05/16/2013] [Accepted: 05/20/2013] [Indexed: 11/17/2022] Open
Abstract
Centhaquin has been reported to be an effective resuscitative agent. The present study was carried out to determine resuscitative effect of centhaquin when administered using a small volume of 3% hypertonic saline (HS) to hemorrhaged rats. Sprague-Dawley rats were anesthetized with urethane, and a pressure catheter SPR-320 was placed in the left femoral artery; another pressure-volume catheter SPR-869 was placed into the left ventricle. Hemorrhage was induced by withdrawing blood and mean arterial pressure (MAP) was maintained at 35 mm Hg for 30 minutes after which resuscitation was performed. Animals were divided in 2 groups: group A received HS and group B received centhaquin (0.05 mg/kg) dissolved in HS. The time by which MAP fell back to 35 mm Hg was observed at that time all animals were administered fresh blood. It was found that centhaquin significantly reduced blood lactate and improved cardiac output and MAP of hemorrhaged rats compared with HS. The time by which MAP fell back to 35 mm Hg in rats treated with HS was 55 ± 6 minutes, whereas it was 161 ± 14 minutes in centhaquin treated rats. Survival time following administration of fresh blood was 79 ± 7 minutes in vehicle-treated group, whereas it was 105 ± 9 minutes in centhaquin-treated rats. The total time of survival of rats treated with HS or centhaquin was 134 ± 12 minutes and 266 ± 16 minutes, respectively. Centhaquin, in small volume, maintained MAP of hemorrhaged rats for a considerable long time and improved the survival time.
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Affiliation(s)
- Anil Gulati
- Department of Pharmaceutical Sciences, Chicago College of Pharmacy, Midwestern University, Downers Grove, IL 60515 USA.
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Zehendner CM, Luhmann HJ, Yang JW. A simple and novel method to monitor breathing and heart rate in awake and urethane-anesthetized newborn rodents. PLoS One 2013; 8:e62628. [PMID: 23658756 PMCID: PMC3643944 DOI: 10.1371/journal.pone.0062628] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Accepted: 03/22/2013] [Indexed: 11/18/2022] Open
Abstract
Rodents are most useful models to study physiological and pathophysiological processes in early development, because they are born in a relatively immature state. However, only few techniques are available to monitor non-invasively heart frequency and respiratory rate in neonatal rodents without restraining or hindering access to the animal. Here we describe experimental procedures that allow monitoring of heart frequency by electrocardiography (ECG) and breathing rate with a piezoelectric transducer (PZT) element without hindering access to the animal. These techniques can be easily installed and are used in the present study in unrestrained awake and anesthetized neonatal C57/Bl6 mice and Wistar rats between postnatal day 0 and 7. In line with previous reports from awake rodents we demonstrate that heart rate in rats and mice increases during the first postnatal week. Respiratory frequency did not differ between both species, but heart rate was significantly higher in mice than in rats. Further our data indicate that urethane, an agent that is widely used for anesthesia, induces a hypoventilation in neonates whilst heart rate remains unaffected at a dose of 1 g per kg body weight. Of note, hypoventilation induced by urethane was not detected in rats at postnatal 0/1. To verify the detected hypoventilation we performed blood gas analyses. We detected a respiratory acidosis reflected by a lower pH and elevated level in CO2 tension (pCO2) in both species upon urethane treatment. Furthermore we found that metabolism of urethane is different in P0/1 mice and rats and between P0/1 and P6/7 in both species. Our findings underline the usefulness of monitoring basic cardio-respiratory parameters in neonates during anesthesia. In addition our study gives information on developmental changes in heart and breathing frequency in newborn mice and rats and the effects of urethane in both species during the first postnatal week.
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Affiliation(s)
- Christoph M. Zehendner
- Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Heiko J. Luhmann
- Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
| | - Jenq-Wei Yang
- Institute of Physiology and Pathophysiology, University Medical Center of the Johannes Gutenberg-University, Mainz, Germany
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Oliveira RC, Campagnole-Santos MJ, Santos RAS. The pressor effect of angiotensin-(1-7) in the rat rostral ventrolateral medulla involves multiple peripheral mechanisms. Clinics (Sao Paulo) 2013; 68:245-52. [PMID: 23525323 PMCID: PMC3584277 DOI: 10.6061/clinics/2013(02)oa20] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 09/16/2012] [Accepted: 10/22/2012] [Indexed: 11/24/2022] Open
Abstract
OBJECTIVE In the present study, the peripheral mechanism that mediates the pressor effect of angiotensin-(1-7) in the rostral ventrolateral medulla was investigated. METHOD Angiotensin-(1-7) (25 pmol) was bilaterally microinjected in the rostral ventrolateral medulla near the ventral surface in urethane-anesthetized male Wistar rats that were untreated or treated (intravenously) with effective doses of selective autonomic receptor antagonists (atenolol, prazosin, methyl-atropine, and hexamethonium) or a vasopressin V1 receptor antagonist [d(CH2)5 -Tyr(Me)-AVP] given alone or in combination. RESULTS Unexpectedly, the pressor response produced by angiotensin-(1-7) (16 ± 2 mmHg, n = 12), which was not associated with significant changes in heart rate, was not significantly altered by peripheral treatment with prazosin, the vasopressin V1 receptor antagonist, hexamethonium or methyl-atropine. Similar results were obtained in experiments that tested the association of prazosin and atenolol; methyl-atropine and the vasopressin V1 antagonist or methyl-atropine and prazosin. Peripheral treatment with the combination of prazosin, atenolol and the vasopressin V1 antagonist abolished the pressor effect of glutamate; however, this treatment produced only a small decrease in the pressor effect of angiotensin-(1-7) at the rostral ventrolateral medulla. The combination of hexamethonium with the vasopressin V1 receptor antagonist or the combination of prazosin, atenolol, the vasopressin V1 receptor antagonist and methyl-atropine was effective in blocking the effect of angiotensin-(1-7) at the rostral ventrolateral medulla. CONCLUSION These results indicate that angiotensin-(1-7) triggers a complex pressor response at the rostral ventrolateral medulla that involves an increase in sympathetic tonus, release of vasopressin and possibly the inhibition of a vasodilatory mechanism.
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Affiliation(s)
- Rita C Oliveira
- Instituto Nacional de Ciência e Tecnologia em Nanobiofarmacêutica, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, Brazil
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Yoshiyama M, Roppolo JR, Takeda M, de Groat WC. Effects of urethane on reflex activity of lower urinary tract in decerebrate unanesthetized rats. Am J Physiol Renal Physiol 2012. [PMID: 23195677 DOI: 10.1152/ajprenal.00574.2012] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Effects of urethane on lower urinary tract function were examined in decerebrate unanesthetized rats. During single slow infusion (0.04 ml/min) cystometrograms (CMGs), urethane (0.3 g/kg) increased micturition pressure threshold (PT) by 73%, postvoid residual volume (RV) by 425%, and decreased voiding efficiency (VE) by 57%, but did not change maximal voiding pressure (MVP), closing peak pressure (CPP), bladder compliance, bladder contraction duration (BCD), or volume threshold (VT) for inducing micturition. Lower doses (0.01-0.1 g/kg) did not alter any parameter. During continuous fast infusion (0.21 ml/min) CMGs, urethane at doses of 0.6-1.2 g/kg (iv) markedly decreased CPP by 69-85%, whereas only the largest dose (1.2 g/kg iv) decreased MVP and external urethral sphincter electromyogram activity by 42 and by 80%, respectively. Doses of 0.001-0.6 g/kg did not alter the intercontraction interval and BCD. Taken together, these results suggest that urethral activity, which is essential for efficient voiding, is more sensitive to the suppressive effect of urethane than afferent or efferent mechanisms controlling the bladder. The threshold dose of MK-801 (0.3 mg/kg), an NMDA antagonist, required to decrease MVP and increase VT in urethane (1.2 g/kg)-anesthetized rats, only increased VT in rats treated with a subanesthetic dose of urethane (0.3 g/kg), suggesting a higher sensitivity of the afferent vs. efferent limb of the micturition reflex pathway to urethane-MK-801 interactions. Because effects of urethane persisted after removal of the forebrain, they must be mediated by actions on the brain stem, spinal cord, or peripheral nervous system.
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Affiliation(s)
- Mitsuharu Yoshiyama
- Department of Urology, University of Yamanashi Interdisciplinary Graduate School of Medicine and Engineering, Chuo, Yamanashi, Japan.
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Lupiński SŁ, Schlicker E, Pędzińska-Betiuk A, Malinowska B. Acute myocardial ischemia enhances the vanilloid TRPV1 and serotonin 5-HT3 receptor-mediated Bezold-Jarisch reflex in rats. Pharmacol Rep 2012; 63:1450-9. [PMID: 22358093 DOI: 10.1016/s1734-1140(11)70709-5] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2011] [Revised: 08/02/2011] [Indexed: 11/26/2022]
Abstract
The Bezold-Jarisch reflex is characterized by a sudden bradycardia associated with hypotension induced by the activation of the vanilloid TRPV1 and serotonin 5-HT(3) receptors. This reflex is associated with several health conditions, including myocardial infarction. The aim of the present study was to elucidate the influence of acute experimental myocardial ischemia on the reflex bradycardia induced by anandamide and phenylbiguanide, agonists of the TRPV1 and 5-HT(3) receptors, respectively. In urethane-anesthetized rats, the rapid iv injection of anandamide (0.6 μmol/kg) or phenylbiguanide (0.03 μmol/kg) decreased heart rate (HR) by about 7-10% of the basal values. Myocardial ischemia (MI) was induced by ligation of the left anterior coronary artery. The agonists were injected 5 min before MI (S(1)) and 10, 20 and 30 min thereafter (S(2)-S(4)). MI potentiated the anandamide-induced reflex bradycardia by approximately 105% at S(2) and 70% at S(3) but had no effect at S(4). This amplificatory effect of MI was virtually abolished by the TRPV1 receptor antagonist capsazepine (1 μmol/kg) and was not modified by the cannabinoid CB(1) receptor antagonist rimonabant (0.1 μmol/kg). MI also amplified the reflex bradycardia elicited by phenylbiguanide by approximately 110, 60 and 90% (S(2), S(3) and S(4), respectively), and this effect was sensitive to the 5-HT(3) receptor antagonist ondansetron (3 μmol/kg). In conclusion, our results suggest that acute myocardial ischemia augments the Bezold-Jarisch reflex induced via activation of TRPV1 and 5-HT(3) receptors located on sensory vagal nerves in the heart.
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Affiliation(s)
- Sebastian Ł Lupiński
- Department of Experimental Physiology and Pathophysiology, Medical University of Białystok, Mickiewicza 2A, PL 15-089 Białystok, Poland
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Abstract
Respiratory activity is most fragile during sleep, in particular during paradoxical [or rapid eye movement (REM)] sleep and sleep state transitions. Rats are commonly used to study respiratory neuromodulation, but rodent sleep is characterized by a highly fragmented sleep pattern, thus making it very challenging to examine different sleep states and potential pharmacological manipulations within them. Sleep-like brain-state alternations occur in rats under urethane anesthesia and may be an effective and efficient model for sleep itself. The present study assessed state-dependent changes in breathing and respiratory muscle modulation under urethane anesthesia to determine their similarity to those occurring during natural sleep. Rats were anesthetized with urethane and respiratory airflow, as well as electromyographic activity in respiratory muscles were recorded in combination with local field potentials in neocortex and hippocampus to determine how breathing pattern and muscle activity are modulated with brain state. Measurements were made in normoxic, hypoxic, and hypercapnic conditions. Results were compared with recordings made from rats during natural sleep. Brain-state alternations under urethane anesthesia were closely correlated with changes in breathing rate and variability and with modulation of respiratory muscle tone. These changes closely mimicked those observed in natural sleep. Of great interest was that, during both REM and REM-like states, genioglossus muscle activity was strongly depressed and abdominal muscle activity showed potent expiratory modulation. We demonstrate that, in urethane-anesthetized rats, respiratory airflow and muscle activity are closely correlated with brain-state transitions and parallel those shown in natural sleep, providing a useful model to systematically study sleep-related changes in respiratory control.
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Protein phosphatase 1b in the solitary tract nucleus is necessary for normal baroreflex function. J Cardiovasc Pharmacol 2012; 59:472-8. [PMID: 22569287 DOI: 10.1097/fjc.0b013e31824ba490] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Despite positive metabolic effects, genetic deletion of protein phosphatase 1b (PTP1b) results in sympathetically mediated elevations in arterial pressure (AP) in mice. Because several PTP1b-regulated peptides also impair the baroreflex sensitivity (BRS) for control of heart rate (HR), we hypothesized that PTP1b in the solitary tract nucleus (NTS) participates in the maintenance of resting baroreflex function. To test this hypothesis, we performed acute bilateral microinjection of an allosteric PTP1b inhibitor (100 nM/120 nL) in the NTS of urethane/chloralose anesthetized Sprague-Dawley rats and assessed the BRS, responses to cardiac vagal chemosensitive fiber activation, and resting AP and HR before and after the injection. PTP1b inhibition impaired the BRS for bradycardia (n = 6; 0.93 ± 0.14 baseline vs. 0.48 ± 0.04 at 10 minutes vs. 0.49 ± 0.04 millisecond/mm Hg at 60 minutes; P < 0.01), with no significant effect on the BRS for tachycardia (0.30 ± 0.16 baseline vs. 0.24 ± 0.08 at 10 minutes vs. 0.24 ± 0.12 millisecond/mm Hg at 60 minutes). The reduced BRS for bradycardia was associated with a significant decrease in alpha-adrenergic responsiveness to phenylephrine at 60 minutes after PTP1b inhibition. Injection of the PTP1b inhibitor in the NTS elicited transient decreases in AP and HR in these animals. However, there was no effect of the inhibitor on depressor or bradycardic responses elicited by activation of cardiac vagal chemosensitive fibers, which converge with baroreceptor afferents in the NTS. These results suggest that PTP1b within the NTS may be a novel molecular mechanism for preservation of resting baroreflex function and provides further evidence for deleterious cardiovascular effects associated with PTP1b inhibition.
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