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Cui CP, Xiong X, Zhao JX, Fu DH, Zhang Y, Ma PB, Wu D, Li BY. Piezo1 channel activation facilitates baroreflex afferent neurotransmission with subsequent blood pressure reduction in control and hypertension rats. Acta Pharmacol Sin 2024; 45:76-86. [PMID: 37670136 PMCID: PMC10770313 DOI: 10.1038/s41401-023-01154-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Accepted: 08/12/2023] [Indexed: 09/07/2023] Open
Abstract
Mechanosensitive cation channels such as Piezo1 and Piezo2 are activated by mechanical force like a starched wall of the aorta while blood pressure (BP) rising, which helps to elucidate the underlying mechanism of mechanotransduction of baroreceptor endings. In this study we investigated how Piezo1 channel activation-mediated gender- and afferent-specific BP regulation in rats. We established high-fat diet and fructose drink-induced hypertension model rats (HFD-HTN) and deoxycorticosterone (DOCA)-sensitive hypertension model rats. We showed that the expression levels of Piezo1 and Piezo2 were significantly up-regulated in left ventricle of HFD and DOCA hypertensive rats, whereas the down-regulation of Piezo1 was likely to be compensated by Piezo2 up-regulation in the aorta. Likewise, down-regulated Piezo1 was observed in the nodose ganglion (NG), while up-regulated Piezo2 was found in the nucleus tractus solitarius (NTS), which might synergistically reduce the excitatory neurotransmitter release from the presynaptic membrane. Notably, microinjection of Yoda1 (0.025-2.5 mg/ml) into the NG concentration-dependently reduced BP in both hypertensive rat models as well as in control rats with similar EC50; the effect of Yoda1 was abolished by microinjection of a Piezo1 antagonist GsMTx4 (1.0 μM). Functional analysis in an in vitro aortic arch preparation showed that instantaneous firing frequency of single Ah-fiber of aortic depressor nerve was dramatically increased by Yoda1 (0.03-1.0 μM) and blocked by GsMTx4 (1.0 μM). Moreover, spontaneous synaptic currents recorded from identified 2nd-order Ah-type baroreceptive neurons in the NTS was also facilitated over 100% by Yoda1 (1.0 μM) and completely blocked by GsMTx4 (3.0 μM). These results demonstrate that Piezo1 expressed on Ah-type baroreceptor and baroreceptive neurons in the NG and NTS plays a key role in a sexual-dimorphic BP regulation under physiological and hypertensive condition through facilitation of baroreflex afferent neurotransmission, which is presumably collaborated by Piezo2 expression at different level of baroreflex afferent pathway via compensatory and synergistic mechanisms.
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Affiliation(s)
- Chang-Peng Cui
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Xue Xiong
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Jia-Xin Zhao
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Dong-Hong Fu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Yan Zhang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Peng-Bo Ma
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Di Wu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
- Department of Pharmacy, The Second Affiliated Hospital of Dalian Medical University, Dalian, 116023, China
| | - Bai-Yan Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China.
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Fu L, Yu B, Li Z, Liu Z. The therapeutic potential of ultra-short-acting β-receptor antagonists in perioperative analgesic: Evidence from preclinical and clinical studies. Front Pharmacol 2022; 13:914710. [PMID: 36304145 PMCID: PMC9592752 DOI: 10.3389/fphar.2022.914710] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 09/20/2022] [Indexed: 12/04/2022] Open
Abstract
Perioperative multimodal analgesia can reduce the side effects of a high concentration of opioids, improving the comfort of the patient. However, insufficient analgesia of this model has prompted researchers to explore new adjuvant analgesics. Recently, an increasing number of studies have found a low-grade analgesic effect in the clinical application of ultra-short-acting β-adrenergic receptor antagonists, which are conventionally used as pharmacologic agents in the cardiovascular system. The mechanism by which ultra-short-acting β-antagonists exert antinociceptive effects has not been clarified yet. In this review, we intend to address its potential reasons from the side of neurotransmitters, inflammatory cytokines, and signaling pathways, providing theoretical proof for the application of β-adrenergic receptor antagonists in analgesia.
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Affiliation(s)
- Linbin Fu
- Department of Anesthesiology, Shenzhen Second People’s Hospital (Shenzhen Institute of Translational Medicine), The First Affiliated Hospital of Shenzhen University, Shenzhen, China
| | - Buwei Yu
- Department of Anesthesiology, Ruijin Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Zheng Li
- Department of Anesthesiology, Shenzhen Second People’s Hospital (Shenzhen Institute of Translational Medicine), The First Affiliated Hospital of Shenzhen University, Shenzhen, China
- *Correspondence: Zheng Li, ; Zhiheng Liu,
| | - Zhiheng Liu
- Department of Anesthesiology, Shenzhen Second People’s Hospital (Shenzhen Institute of Translational Medicine), The First Affiliated Hospital of Shenzhen University, Shenzhen, China
- *Correspondence: Zheng Li, ; Zhiheng Liu,
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Wu D, Zhao D, Huang D, Sun X, Li KX, Feng Y, Yan QX, Li XY, Cui CP, Li HD, Li BY. Estrogen-dependent depressor response of melatonin via baroreflex afferent function and intensification of PKC-mediated Na v1.9 activation. Acta Pharmacol Sin 2022; 43:2313-2324. [PMID: 35132193 PMCID: PMC9433371 DOI: 10.1038/s41401-022-00867-w] [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: 11/23/2021] [Accepted: 01/16/2022] [Indexed: 11/09/2022] Open
Abstract
Recent studies suggest that melatonin (Mel) plays an important role in the regulation of blood pressure (BP) via the aortic baroreflex pathway. In this study, we investigated the interaction between the baroreflex afferent pathway and Mel-mediated BP regulation in rats under physiological and hypertensive conditions. Mel (0.1, 0.3, and 1.0 mg/mL) was microinjected into the nodose ganglia (NG) of rats. We showed that Mel-induced reduction of mean arterial pressure in female rats was significantly greater than that in male and in ovariectomized rats under physiological condition. Consistently, the expression of Mel receptors (MTNRs) in the NG of female rats was significantly higher than that of males. In L-NAME-induced hypertensive and spontaneously hypertensive rat models, MTNRs were upregulated in males but downregulated in female models. Interestingly, Mel-induced BP reduction was found in male hypertensive models. In whole-cell recording from identified baroreceptor neurons (BRNs) in female rats, we found that Mel (0.1 μM) significantly increased the excitability of a female-specific subpopulation of Ah-type BRNs by increasing the Nav1.9 current density via a PKC-mediated pathway. Similar results were observed in baroreceptive neurons of the nucleus tractus solitarius, showing the facilitation of spontaneous and evoked excitatory post-synaptic currents in Ah-type neurons. Collectively, this study reveals the estrogen-dependent effect of Mel/MTNRs under physiological and hypertensive conditions is mainly mediated by Ah-type BRNs, which may provide new theoretical basis and strategies for the gender-specific anti-hypertensive treatment in clinical practice.
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Affiliation(s)
- Di Wu
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
- Department of Pharmacy, The Second Affiliated Hospital of Dalian Medical University, Dalian, 116023, China
| | - Dan Zhao
- Department of Clinical Pharmacy, The Second Affiliated Hospital of Harbin Medical University, Harbin, 150086, China
| | - Di Huang
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Xun Sun
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Ke-Xin Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Yan Feng
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Qiu-Xin Yan
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Xin-Yu Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Chang-Peng Cui
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Hu-Die Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China
| | - Bai-Yan Li
- Department of Pharmacology (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China, Key Laboratory of Cardiovascular Medicine Research, Ministry of Education), College of Pharmacy, Harbin Medical University, Harbin, 150081, China.
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Liu H, Duan SR. Prostaglandin E2-mediated upregulation of neuroexcitation and persistent tetrodotoxin-resistant Na(+) currents in Ah-type trigeminal ganglion neurons isolated from adult female rats. Neuroscience 2016; 320:194-204. [PMID: 26868972 DOI: 10.1016/j.neuroscience.2016.02.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 01/31/2016] [Accepted: 02/03/2016] [Indexed: 11/16/2022]
Abstract
Prostaglandin-E2 (PGE2) is a very important inflammatory mediator and PGE2-mediated neuroexcitation in sex-specific distribution of Ah-type trigeminal ganglion neurons (TGNs) isolated from adult female rats is not fully addressed. The whole-cell patch-clamp experiment was performed to verify the effects of PGE2, forskolin, and GPR30-selective agonist (G-1) on action potential (AP) and tetrodotoxin-resistant (TTX-R) Na(+) currents in identified Ah-type TGNs. The results showed that the firing frequency was increased in Ah- and C-types by PGE2, which was simulated by forskolin and inhibited by Rp-cyclic adenosine monophosphate (cAMP), while G-1 mimicked this effect only in Ah-types, which was abolished by GPR30-selective antagonist (G-15). Although the amplitude of AP was increased in Ah- and C-types, increased maximal upstroke velocity was confirmed only in Ah-types, suggesting distinct alternations in current density and/or voltage-dependent property of Na(+) channels. With 1.0 μM PGE2, TTX-R Na(+) currents were upregulated without changing the current-voltage relationship and voltage-dependent activation in C-types, however, the TTX-R Na(+) current was augmented in Ah-types, peaked voltage and the voltage-dependent activation were both shifted toward hyperpolarized direction with faster slope. Intriguingly, the low-threshold persistent TTX-R component was activated from -60 mV and increased almost double at -30 mV compared with ∼30-40% increment of TTX-R component being activated at ∼-10 mV. Additionally, the change in TTX-R component of Ah-types was equivalent well with that in C-type TGNs. Taken these data together, we conclude that PGE2 modulates the neuroexcitation via cAMP-mediated upregulation of TTX-R Na(+) currents in both cell-types with hormone-dependent feature, especially persistent TTX-R Na(+) currents in sex-specific distribution of myelinated Ah-type TGNs.
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Affiliation(s)
- H Liu
- Department of Neurology, The Fourth Affiliated Hospital of Harbin Medical University, Harbin, China.
| | - S-R Duan
- Department of Neurology, The First Affiliated Hospital of Harbin Medical University, Harbin, China
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Qian Z, Liu DJ, Liu Y, Han LM, Yuan M, Li JN, Xu B, Lu XL, Cao PX, Wang HY, Pan XD, Wang LJ, Qiao GF, Li BY. Increase in neuroexcitability of unmyelinated C-type vagal ganglion neurons during initial postnatal development of visceral afferent reflex functions. CNS Neurosci Ther 2013; 19:954-62. [PMID: 24164691 DOI: 10.1111/cns.12195] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2013] [Revised: 09/22/2013] [Accepted: 09/23/2013] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND Baroreflex gain increase up closely to adult level during initial postnatal weeks, and any interruption within this period will increase the risk of cardiovascular problems in later of life span. We hypothesize that this short period after birth might be critical for postnatal development of vagal ganglion neurons (VGNs). METHODS To evaluate neuroexcitability evidenced by discharge profiles and coordinate changes, ion currents were collected from identified A- and C-type VGNs at different developmental stages using whole-cell patch clamping. RESULTS C-type VGNs underwent significant age-dependent transition from single action potential (AP) to repetitive discharge. The coordinate changes between TTX-S and TTX-R Na(+) currents were also confirmed and well simulated by computer modeling. Although 4-AP or iberiotoxin age dependently increased firing frequency, AP duration was prolonged in an opposite fashion, which paralleled well with postnatal changes in 4-AP- and iberiotoxin-sensitive K(+) current activity, whereas less developmental changes were verified in A-types. CONCLUSION These data demonstrate for the first time that the neuroexcitability of C-type VGNs increases significantly compared with A-types within initial postnatal weeks evidenced by AP discharge profiles and coordinate ion channel changes, which explain, at least in part, that initial postnatal weeks may be crucial for ontogenesis in visceral afferent reflex function.
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Affiliation(s)
- Zhao Qian
- Department of Pharmacology, Harbin Medical University, Harbin, China
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Lu XL, Xu WX, Yan ZY, Qian Z, Xu B, Liu Y, Han LM, Gao RC, Li JN, Yuan M, Zhao CB, Qiao GF, Li BY. Subtype identification in acutely dissociated rat nodose ganglion neurons based on morphologic parameters. Int J Biol Sci 2013; 9:716-27. [PMID: 23904796 PMCID: PMC3729014 DOI: 10.7150/ijbs.7006] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 07/01/2013] [Indexed: 01/04/2023] Open
Abstract
Nodose ganglia are composed of A-, Ah- and C-type neurons. Despite their important roles in regulating visceral afferent function, including cardiovascular, pulmonary, and gastrointestinal homeostasis, information about subtype-specific expression, molecular identity, and function of individual ion transporting proteins is scarce. Although experiments utilizing the sliced ganglion preparation have provided valuable insights into the electrophysiological properties of nodose ganglion neuron subtypes, detailed characterization of their electrical phenotypes will require measurements in isolated cells. One major unresolved problem, however, is the difficulty to unambiguously identify the subtype of isolated nodose ganglion neurons without current-clamp recording, because the magnitude of conduction velocity in the corresponding afferent fiber, a reliable marker to discriminate subtypes in situ, can no longer be determined. Here, we present data supporting the notion that application of an algorithm regarding to microscopic structural characteristics, such as neuron shape evaluated by the ratio between shortest and longest axis, neuron surface characteristics, like membrane roughness, and axon attachment, enables specific and sensitive subtype identification of acutely dissociated rat nodose ganglion neurons, by which the accuracy of identification is further validated by electrophysiological markers and overall positive predictive rates is 89.26% (90.04%, 76.47%, and 98.21% for A-, Ah, and C-type, respectively). This approach should aid in gaining insight into the molecular correlates underlying phenotypic heterogeneity of nodose ganglia. Additionally, several critical points that help for neuron identification and afferent conduction calibration are also discussed.
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Affiliation(s)
- Xiao-Long Lu
- Department of Pharmacology, Harbin Medical University, Harbin, China
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Copel C, Clerc N, Osorio N, Delmas P, Mazet B. The Nav1.9 channel regulates colonic motility in mice. Front Neurosci 2013; 7:58. [PMID: 23596386 PMCID: PMC3625748 DOI: 10.3389/fnins.2013.00058] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 03/28/2013] [Indexed: 01/07/2023] Open
Abstract
The colonic migrating motor complex (CMMC) is a major pattern of motility that is entirely generated and organized by the enteric nervous system. We have previously demonstrated that the Nav1.9 channel underlies a tetrodotoxin-resistant sodium current which modulates the excitability of enteric neurons. The aim of this study was to observe the effect of loss of the Nav1.9 channel in enteric neurons on mouse colonic motility in vitro. The mechanical activity of the circular muscle was simultaneously recorded from three sites, namely, proximal, mid- and distal, along the whole colon of male, age-matched wild-type and Nav1.9 null mice. Spontaneous CMMCs were observed in all preparations. The mean frequency of CMMCs was significantly higher in the Nav1.9 null mice (one every 2.87 ± 0.1 min compared to one every 3.96 ± 0.23 min in the wild type). The mean duration of CMMCs was shorter and the mean area-under-contraction was larger in the Nav1.9 null mice compared to the wild type. In addition, CMMCs propagated preferentially in an aboral direction in the Nav1.9 null mice. Our study demonstrates that CMMCs do occur in mice lacking the Nav1.9 channel, but their characteristics are significantly different from controls. Up to now, the Nav1.9 channel was mainly associated with nociceptive neurons and involved in their hyperexcitability after inflammation. Our result shows for the first time a role for the Nav1.9 channel in a complex colonic motor pattern.
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Affiliation(s)
- Carine Copel
- Aix Marseille Université, CNRS, CRN2M UMR 7286 Marseille, France
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Gresham K, Boyer B, Mayer C, Foglyano R, Martin R, Wilson CG. Airway inflammation and central respiratory control: results from in vivo and in vitro neonatal rat. Respir Physiol Neurobiol 2011; 178:414-21. [PMID: 21609789 DOI: 10.1016/j.resp.2011.05.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2011] [Revised: 05/08/2011] [Accepted: 05/10/2011] [Indexed: 11/16/2022]
Abstract
In infants, respiratory infection elicits tachypnea. To begin to evaluate the role of brainstem cytokine expression in modulation of breathing pattern changes, we compared the pattern generated after endotracheal instillation of lipopolysaccharide (LPS) in in vivo rat pups to local pro-inflammatory cytokine injection in the nucleus tractus solitarius (nTS) in an in vitro en bloc brainstem spinal cord preparation. We hypothesized that both challenges would elicit similar changes in patterning of respiration. In anesthetized, spontaneously breathing rat pups, lipopolysaccharide (LPS) or saline was instilled in the airway of urethane-anesthetized rats (postnatal days 10-11). We recorded diaphragm EMG over the subsequent 2h and saw a 20-30% decrease in interburst interval (Te) at 20-80min post-injection in LPS-instilled animals with no significant change in Ti. In contrast, IL-1β injections into the nTS of en bloc in vitro brainstem-spinal cord preparations from 0 to 5 day-old pups maintained Ti and caused an increase in Te as early as 20min later, decreasing frequency for 80-120min after injection. Our results suggest that the neonatal respiratory response to the cytokine IL-1β mediated inflammatory response depends on the site of the inflammatory stimulus and that the direct effect of IL-1β in the nTS is to slow rather than increase rate.
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Affiliation(s)
- Kenneth Gresham
- Department of Pediatrics, Case Western Reserve University, Cleveland, OH 44106, United States
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Ebersberger A, Natura G, Eitner A, Halbhuber KJ, Rost R, Schaible HG. Effects of prostaglandin D2 on tetrodotoxin-resistant Na+ currents in DRG neurons of adult rat. Pain 2011; 152:1114-1126. [DOI: 10.1016/j.pain.2011.01.033] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Revised: 12/23/2010] [Accepted: 01/18/2011] [Indexed: 11/28/2022]
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Qiao GF, Li BY, Zhou YH, Lu YJ, Schild JH. Characterization of persistent TTX-R Na+ currents in physiological concentration of sodium in rat visceral afferents. Int J Biol Sci 2009; 5:293-7. [PMID: 19365577 PMCID: PMC2667275 DOI: 10.7150/ijbs.5.293] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Accepted: 03/30/2009] [Indexed: 11/26/2022] Open
Abstract
Persistent tetrodotoxin-resistant (TTX-R) Na+ (Nav1.9/SCN11A) currents are not normally recorded in vagal afferent neurons (VANs) with 50 mM of extracellular Na+ although the functional expression of this current was observed in the presence of PGE2 or forskolin. However, it is uncertain whether this current can be seen under physiological condition (150 mM Na+). Using the whole-cell patch-clamp technique, we showed that persistent TTX-R Na+ currents were expressed in 9 out of 38 VANs bathed in 150 mM Na+. The current density, but not the whole-cell capacitance, was significantly enhanced in the VANs expressing Nav1.9. Persistent TTX-R Na+ channels were activated at a more hyperpolarized membrane potential near -60 mV, compared with TTX-sensitive (TTX-S at -40 mV) and TTX-R Na+ channels (at -20 mV). This indicates that persistent TTX-R Na+ channels provide a wider activation window than TTX-S and TTX-R Na channels to up-regulate neuronal excitability. These results suggest that the persistent TTX-R Na+ currents may be involved in the neuronal excitability by setting a lower pressure-discharge threshold and higher discharge frequency of VANs, especially the unique subset and gender-specific distribution of myelinated Ah-type VANs, including Ah-type aortic baroreceptor neurons, identified in our previous study.
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Affiliation(s)
- Guo-Fen Qiao
- Department of Pharmacology, Harbin Medical University, Harbin, China
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Qiao GF, Cheng ZF, Huo R, Sui XH, Lu YJ, Li BY. GM1 ganglioside contributes to retain the neuronal conduction and neuronal excitability in visceral and baroreceptor afferents. J Neurochem 2008; 106:1637-45. [PMID: 18547369 DOI: 10.1111/j.1471-4159.2008.05515.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
GM1 ganglioside has a great impact on the function of nodes of Ranvier on myelinated fiber, suggesting its potential role to maintain the electrical and neuronal excitability of neurons. Here we first demonstrate that visceral afferent conduction velocity of myelinated and unmyelinated fibers are reduced significantly by tetrodotoxin (TTX) or cholera toxin-B subunits (CTX-B), and only the effects mediated by CTX-B are prevented by GM1 pre-treatment. At soma of myelinated A and unmyelinated C-type nodose ganglion neurons (NGNs), the action potential spike frequency reduced by CTX-B is also prevented by GM1. Additionally, the current density of both TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) Na(+) channels were significantly decreased by CTX-B without changing the voltage-dependent property. These data confirm that endogenous GM1 may play a dominant role in maintaining the electrical and neuronal excitability via modulation of sodium (Na(+)) channel around nodes and soma as well, especially TTX-S Na(+) channel, which is also confirmed by the reduction of spike amplitude and depolarization. Similar data are also extended to fluorescently identified and electrophysiologically characterized aortic baroreceptor neurons. These findings suggest that GM1 plays an important role in the neural modulation of electric and neuronal excitability in visceral afferent system.
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Affiliation(s)
- Guo-Fen Qiao
- Department of Pharmacology, Harbin Medical University, Harbin, China
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