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Rodrigues LTC, Patrone LGA, Gargaglioni LH, Dias MB. Melanin-concentrating hormone regulates the hypercapnic chemoreflex by acting in the lateral hypothalamic area. Exp Physiol 2022; 107:1298-1311. [PMID: 35930596 DOI: 10.1113/ep090318] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 07/22/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? MCH suppresses the hypercapnic chemoreflex but the mechanism by which this effect is produced has not been previously explored. What is the main finding and its importance? MCH acting in the lateral hypothalamic area but not in the locus coeruleus in rats, in the light period, attenuates the hypercapnic chemoreflex. Our data provide new insight regarding the role of MCH in the modulation of the hypercapnic ventilatory response. ABSTRACT Melanin-concentrating hormone (MCH) is a hypothalamic neuropeptide involved in a broad range of homeostatic functions including regulation of the hypercapnic chemoreflex. We evaluated whether MCH modulates the hypercapnic ventilatory response by acting in the lateral hypothalamic area (LHA) and/or in the locus coeruleus (LC). Here, we measured pulmonary ventilation (VE ), body temperature, electroencephalogram (EEG) and electromyogram (EMG) of unanesthetized adult male Wistar rats before and after microinjection of MCH [0.4 mM] or MCH1-R antagonist (SNAP-94847 [63 mM]) into the LHA and LC, in room air and 7% CO2 conditions during wakefulness and sleep, in the dark and light periods. MCH intra-LHA caused a decreased CO2 ventilatory response during wakefulness and sleep in the light period, while SNAP-94847 intra-LHA increased this response, during wakefulness in the light period. In the LC, MCH or the MCH1-R antagonist caused no change in the hypercapnic ventilatory response. Our results suggest that MCH, in the LHA, exerts an inhibitory modulation of the hypercapnic ventilatory response during the light-inactive period in rats. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Laísa T C Rodrigues
- Department of Structural and Functional Biology, Institute of Biosciences, Sao Paulo State University-UNESP, Botucatu, SP, Brazil
| | - Luis Gustavo A Patrone
- Department of Animal Morphology and Physiology, Sao Paulo State University-FCAV, Jaboticabal, SP, Brazil
| | - Luciane H Gargaglioni
- Department of Animal Morphology and Physiology, Sao Paulo State University-FCAV, Jaboticabal, SP, Brazil
| | - Mirela B Dias
- Department of Structural and Functional Biology, Institute of Biosciences, Sao Paulo State University-UNESP, Botucatu, SP, Brazil
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Barnett S, Li A. Orexin in Respiratory and Autonomic Regulation, Health and Diseases. Compr Physiol 2020; 10:345-363. [DOI: 10.1002/cphy.c190013] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Diniz GB, Bittencourt JC. The Melanin-Concentrating Hormone (MCH) System: A Tale of Two Peptides. Front Neurosci 2019; 13:1280. [PMID: 31849590 PMCID: PMC6901935 DOI: 10.3389/fnins.2019.01280] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 11/11/2019] [Indexed: 12/19/2022] Open
Abstract
The melanin-concentrating hormone (MCH) system is a robust integrator of exogenous and endogenous information, modulating arousal and energy balance in mammals. Its predominant function in teleosts, however, is to concentrate melanin in the scales, contributing to the adaptive color change observed in several teleost species. These contrasting functions resulted from a gene duplication that occurred after the teleost divergence, which resulted in the generation of two MCH-coding genes in this clade, which acquired distinctive sequences, distribution, and functions, examined in detail here. We also describe the distribution of MCH immunoreactivity and gene expression in a large number of species, in an attempt to identify its core elements. While initially originated as a periventricular peptide, with an intimate relationship with the third ventricle, multiple events of lateral migration occurred during evolution, making the ventrolateral and dorsolateral hypothalamus the predominant sites of MCH in teleosts and mammals, respectively. Substantial differences between species can be identified, likely reflecting differences in habitat and behavior. This observation aligns well with the idea that MCH is a major integrator of internal and external information, ensuring an appropriate response to ensure the organism’s homeostasis. New studies on the MCH system in species that have not yet been investigated will help us understand more precisely how these habitat changes are connected to the hypothalamic neurochemical circuits, paving the way to new intervention strategies that may be used with pharmacological purposes.
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Affiliation(s)
- Giovanne B Diniz
- Departamento de Anatomia, Instituto de Ciências Biomedicas, Universidade de São Paulo, São Paulo, Brazil.,Department of Neurosurgery, Yale School of Medicine, New Haven, CT, United States
| | - Jackson C Bittencourt
- Departamento de Anatomia, Instituto de Ciências Biomedicas, Universidade de São Paulo, São Paulo, Brazil.,Nucleo de Neurociencias e Comportamento, Instituto de Psicologia, Universidade de São Paulo, São Paulo, Brazil
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Simeone KA, Hallgren J, Bockman CS, Aggarwal A, Kansal V, Netzel L, Iyer SH, Matthews SA, Deodhar M, Oldenburg PJ, Abel PW, Simeone TA. Respiratory dysfunction progresses with age in Kcna1-null mice, a model of sudden unexpected death in epilepsy. Epilepsia 2018; 59:345-357. [PMID: 29327348 DOI: 10.1111/epi.13971] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/12/2017] [Indexed: 12/17/2022]
Abstract
OBJECTIVE Increased breathing rate, apnea, and respiratory failure are associated with sudden unexpected death in epilepsy (SUDEP). We recently demonstrated the progressive nature of epilepsy and mortality in Kcna1-/- mice, a model of temporal lobe epilepsy and SUDEP. Here we tested the hypothesis that respiratory dysfunction progresses with age in Kcna1-/- mice, thereby increasing risk of respiratory failure and sudden death (SD). METHODS Respiratory parameters were determined in conscious mice at baseline and following increasing doses of methacholine (MCh) using noninvasive airway mechanics (NAM) systems. Kcna1+/+ , Kcna1+/- , and Kcna1-/- littermates were assessed during 3 age ranges when up to ~30%, ~55%, and ~90% of Kcna1-/- mice have succumbed to SUDEP: postnatal day (P) 32-36, P40-46, and P48-56, respectively. Saturated arterial O2 (SaO2 ) was determined with pulse oximetry. Lung and brain tissues were isolated and Kcna1 gene and protein expression were evaluated by reverse transcriptase quantitative polymerase chain reaction (RT-qPCR) and Western blot techniques. Airway smooth muscle responsiveness was assessed in isolated trachea exposed to MCh. RESULTS Kcna1-/- mice experienced an increase in basal respiratory drive, chronic oxygen desaturation, frequent apnea-hypopnea (A-H), an atypical breathing sequence of A-H-tachypnea-A-H, increased tidal volume, and hyperventilation induced by MCh. The MCh-provoked hyperventilation was dramatically attenuated with age. Of interest, only Kcna1-/- mice developed seizures following exposure to MCh. Seizures were provoked by lower concentrations of MCh as Kcna1-/- mice approached SD. MCh-induced seizures experienced by a subset of younger Kcna1-/- mice triggered death. Respiratory parameters of these younger Kcna1-/- mice resembled older near-SD Kcna1-/- mice. Kcna1 gene and protein were not expressed in Kcna1+/+ and Kcna1+/- lungs, and MCh-mediated airway smooth muscle contractions exhibited similar half-maximal effective concentration( EC50 ) in isolated Kcna1+/+ and Kcna1-/- trachea. SIGNIFICANCE The Kcna1-/- model of SUDEP exhibits progressive respiratory dysfunction, which suggests a potential increased susceptibility for respiratory failure during severe seizures that may result in sudden death.
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Affiliation(s)
- Kristina A Simeone
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Jodi Hallgren
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Charles S Bockman
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Ankita Aggarwal
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Vikash Kansal
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Lauren Netzel
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Shruthi H Iyer
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Stephanie A Matthews
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Malavika Deodhar
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Peter J Oldenburg
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA.,Department of Pharmacology and Experimental Neuroscience, University of Nebraska Medical Center, Omaha, NE, USA
| | - Peter W Abel
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
| | - Timothy A Simeone
- Department of Pharmacology, Creighton University School of Medicine, Omaha, NE, USA
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Amin R, Simakajornboon N, Szczesniak R, Inge T. Early improvement in obstructive sleep apnea and increase in orexin levels after bariatric surgery in adolescents and young adults. Surg Obes Relat Dis 2016; 13:95-100. [PMID: 27720196 DOI: 10.1016/j.soard.2016.05.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Revised: 05/02/2016] [Accepted: 05/25/2016] [Indexed: 11/18/2022]
Abstract
BACKGROUND Obstructive sleep apnea (OSA) associated with obesity is known to improve after bariatric surgery, but little is known about early changes in this condition after surgery. OBJECTIVES To study the clinical course of OSA after bariatric surgery SETTING: Children's hospital in the United States METHODS: Adolescents and young adults with obstructive sleep apnea undergoing vertical sleeve gastrectomy (n = 6) or gastric bypass (n = 1) were enrolled in this prospective study. Participants underwent formal polysomnography before and at 3 and 5 weeks after bariatric surgery. Anthropometric measurements and assay for orexin and leptin were also performed at study visits. Thirty-one adolescents who underwent 2 polysomnography studies that were 4 weeks apart served as control patients. RESULTS Baseline mean (range) age of participants was 17.8 (15.4-20.7) years, 71% were male, with body mass index of 55.2 (41.3-61.6) kg/m2 and had a median apnea hypopnea index (AHI) of 15.8 (7.1-23.8) events/hour. Differences in least-square means from longitudinal analysis did not show significant differences in AHI in the control group but showed significant postoperative decline in AHI relative to baseline. AHI declined postoperatively from baseline by 9.2 events/hour (95% confidence interval: 3.8 to 14.5) at 3 weeks (P = .002) and 9.1 events/hour (95% confidence interval: 3.8 to 14.5) at 5 weeks (P = .002); there was no significant change from 3 to 5 weeks in AHI. Leptin decreased and orexin levels increased significantly by 3 weeks postoperatively. CONCLUSIONS These observations suggest that OSA responds early and out of proportion to weight loss after metabolic and or bariatric surgery, thus weight independent factors may at least in part be responsible for early improvement in OSA postoperatively.
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Affiliation(s)
- Raouf Amin
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Sleep Disorders Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio.
| | - Narong Simakajornboon
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; Sleep Disorders Center, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Rhonda Szczesniak
- Division of Pulmonary Medicine, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio; University of Cincinnati Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
| | - Thomas Inge
- Surgical Weight Loss Center for Teens, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio
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Hu B, Yang N, Qiao QC, Hu ZA, Zhang J. Roles of the orexin system in central motor control. Neurosci Biobehav Rev 2014; 49:43-54. [PMID: 25511388 DOI: 10.1016/j.neubiorev.2014.12.005] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Revised: 11/10/2014] [Accepted: 12/03/2014] [Indexed: 12/15/2022]
Abstract
The neuropeptides orexin-A and orexin-B are produced by one group of neurons located in the lateral hypothalamic/perifornical area. However, the orexins are widely released in entire brain including various central motor control structures. Especially, the loss of orexins has been demonstrated to associate with several motor deficits. Here, we first summarize the present knowledge that describes the anatomical and morphological connections between the orexin system and various central motor control structures. In the next section, the direct influence of orexins on related central motor control structures is reviewed at molecular, cellular, circuitry, and motor activity levels. After the summarization, the characteristic and functional relevance of the orexin system's direct influence on central motor control function are demonstrated and discussed. We also propose a hypothesis as to how the orexin system orchestrates central motor control in a homeostatic regulation manner. Besides, the importance of the orexin system's phasic modulation on related central motor control structures is highlighted in this regulation manner. Finally, a scheme combining the homeostatic regulation of orexin system on central motor control and its effects on other brain functions is presented to discuss the role of orexin system beyond the pure motor activity level, but at the complex behavioral level.
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Affiliation(s)
- Bo Hu
- Department of Physiology, College of Basic Medical Sciences, Third Military Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing 400038, PR China
| | - Nian Yang
- Department of Physiology, College of Basic Medical Sciences, Third Military Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing 400038, PR China
| | - Qi-Cheng Qiao
- Department of Physiology, College of Basic Medical Sciences, Third Military Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing 400038, PR China
| | - Zhi-An Hu
- Department of Physiology, College of Basic Medical Sciences, Third Military Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing 400038, PR China.
| | - Jun Zhang
- Department of Physiology, College of Basic Medical Sciences, Third Military Medical University, 30 Gaotanyan Street, Shapingba District, Chongqing 400038, PR China.
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Li N, Nattie E, Li A. The role of melanin concentrating hormone (MCH) in the central chemoreflex: a knockdown study by siRNA in the lateral hypothalamus in rats. PLoS One 2014; 9:e103585. [PMID: 25084113 PMCID: PMC4118894 DOI: 10.1371/journal.pone.0103585] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 06/30/2014] [Indexed: 11/19/2022] Open
Abstract
Melanin concentrating hormone (MCH), a neuropeptide produced mainly in neurons localized to the lateral hypothalamic area (LHA), has been implicated in the regulation of food intake, energy balance, sleep state, and the cardiovascular system. Hypothalamic MCH neurons also have multisynaptic connections with diaphragmatic motoneurons and project to many central chemoreceptor sites. However, there are few studies of MCH involvement in central respiratory control. To test the hypothesis that MCH plays a role in the central chemoreflex, we induced a down regulation of MCH in the central nervous system by knocking down the MCH precursor (pMCH) mRNA in the LHA using a pool of small interfering RNA (siRNA), and measured the resultant changes in breathing, metabolic rate, body weight, and blood glucose levels in conscious rats. The injections of pMCH-siRNA into the LHA successfully produced a ∼62% reduction of pMCH mRNA expression in the LHA and a ∼43% decrease of MCH levels in the cerebrospinal fluid relative to scrambled-siRNA treatment (P = 0.006 and P = 0.02 respectively). Compared to the pretreatment baseline and the scrambled-siRNA treated control rats, knockdown of MCH resulted in: 1) an enhanced hypercapnic chemoreflex (∼42 & 47% respectively; P < 0.05) only in wakefulness; 2) a decrease in body weight and basal glucose levels; and 3) an unchanged metabolic rate. Our results indicate that MCH participates not only in the regulation of glucose and sleep-wake homeostasis but also the vigilance-state dependent regulation of the central hypercapnic chemoreflex and respiratory control.
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Affiliation(s)
- Ningjing Li
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America
| | - Eugene Nattie
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America
| | - Aihua Li
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth, Lebanon, New Hampshire, United States of America
- * E-mail:
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8
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Abstract
In this review we focus on the role of orexin in cardio-respiratory functions and its potential link to hypertension. (1) Orexin, cardiovascular function, and hypertension. In normal rats, central administration of orexin can induce significant increases in arterial blood pressure (ABP) and sympathetic nerve activity (SNA), which can be blocked by orexin receptor antagonists. In spontaneously hypertensive rats (SHRs), antagonizing orexin receptors can significantly lower blood pressure under anesthetized or conscious conditions. (2) Orexin, respiratory function, and central chemoreception. The prepro-orexin knockout mouse has a significantly attenuated ventilatory CO2 chemoreflex, and in normal rats, central application of orexin stimulates breathing while blocking orexin receptors decreases the ventilatory CO2 chemoreflex. Interestingly, SHRs have a significantly increased ventilatory CO2 chemoreflex relative to normotensive WKY rats and blocking both orexin receptors can normalize this exaggerated response. (3) Orexin, central chemoreception, and hypertension. SHRs have higher ABP and SNA along with an enhanced ventilatory CO2 chemoreflex. Treating SHRs by blocking both orexin receptors with oral administration of an antagonist, almorexant (Almxt), can normalize the CO2 chemoreflex and significantly lower ABP and SNA. We interpret these results to suggest that the orexin system participates in the pathogenesis and maintenance of high blood pressure in SHRs, and the central chemoreflex may be a causal link to the increased SNA and ABP in SHRs. Modulation of the orexin system could be a potential target in treating some forms of hypertension.
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Affiliation(s)
- Aihua Li
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - Eugene Nattie
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
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Li A, Nattie E. Orexin, cardio-respiratory function, and hypertension. Front Neurosci 2014; 8:22. [PMID: 24574958 PMCID: PMC3921571 DOI: 10.3389/fnins.2014.00022] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 01/25/2014] [Indexed: 01/30/2023] Open
Abstract
In this review we focus on the role of orexin in cardio-respiratory functions and its potential link to hypertension. (1) Orexin, cardiovascular function, and hypertension. In normal rats, central administration of orexin can induce significant increases in arterial blood pressure (ABP) and sympathetic nerve activity (SNA), which can be blocked by orexin receptor antagonists. In spontaneously hypertensive rats (SHRs), antagonizing orexin receptors can significantly lower blood pressure under anesthetized or conscious conditions. (2) Orexin, respiratory function, and central chemoreception. The prepro-orexin knockout mouse has a significantly attenuated ventilatory CO2 chemoreflex, and in normal rats, central application of orexin stimulates breathing while blocking orexin receptors decreases the ventilatory CO2 chemoreflex. Interestingly, SHRs have a significantly increased ventilatory CO2 chemoreflex relative to normotensive WKY rats and blocking both orexin receptors can normalize this exaggerated response. (3) Orexin, central chemoreception, and hypertension. SHRs have higher ABP and SNA along with an enhanced ventilatory CO2 chemoreflex. Treating SHRs by blocking both orexin receptors with oral administration of an antagonist, almorexant (Almxt), can normalize the CO2 chemoreflex and significantly lower ABP and SNA. We interpret these results to suggest that the orexin system participates in the pathogenesis and maintenance of high blood pressure in SHRs, and the central chemoreflex may be a causal link to the increased SNA and ABP in SHRs. Modulation of the orexin system could be a potential target in treating some forms of hypertension.
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Affiliation(s)
- Aihua Li
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
| | - Eugene Nattie
- Department of Physiology and Neurobiology, Geisel School of Medicine at Dartmouth Lebanon, NH, USA
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Abstract
There is a growing public awareness that hormones can have a significant impact on most biological systems, including the control of breathing. This review will focus on the actions of two broad classes of hormones on the neuronal control of breathing: sex hormones and stress hormones. The majority of these hormones are steroids; a striking feature is that both groups are derived from cholesterol. Stress hormones also include many peptides which are produced primarily within the paraventricular nucleus of the hypothalamus (PVN) and secreted into the brain or into the circulatory system. In this article we will first review and discuss the role of sex hormones in respiratory control throughout life, emphasizing how natural fluctuations in hormones are reflected in ventilatory metrics and how disruption of their endogenous cycle can predispose to respiratory disease. These effects may be mediated directly by sex hormone receptors or indirectly by neurotransmitter systems. Next, we will discuss the origins of hypothalamic stress hormones and their relationship with the respiratory control system. This relationship is 2-fold: (i) via direct anatomical connections to brainstem respiratory control centers, and (ii) via steroid hormones released from the adrenal gland in response to signals from the pituitary gland. Finally, the impact of stress on the development of neural circuits involved in breathing is evaluated in animal models, and the consequences of early stress on respiratory health and disease is discussed.
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Affiliation(s)
- Mary Behan
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin, USA.
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Effects of hypocretin and norepinephrine interaction in bed nucleus of the stria terminalis on arterial pressure. Neuroscience 2013; 255:278-91. [PMID: 24070630 DOI: 10.1016/j.neuroscience.2013.09.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2013] [Revised: 09/16/2013] [Accepted: 09/16/2013] [Indexed: 11/20/2022]
Abstract
Forebrain neuronal circuits containing hypocretin-1 (hcrt-1) and norepinephrine (NE) are important components of central arousal-related processes. Recently, these two systems have been shown to have an overlapping distribution within the bed nucleus of the stria terminalis (BST), a limbic structure activated by stressful challenges, and which functions to adjust arterial pressure (AP) and heart rate (HR) to the stressor. However, whether hcrt-1 and NE interact in BST to alter cardiovascular function is unknown. Experiments were done in urethane-α-chloralose anesthetized, paralyzed, and artificially ventilated male Wistar rats to investigate the effect of hcrt-1 and NE on the cardiovascular responses elicited by l-glutamate (Glu) stimulation of BST neurons. Microinjections of hcrt-1, NE or tyramine into BST attenuated the decrease in AP and HR to Glu stimulation of BST. Additionally, combined injections of hcrt-1 with NE or tyramine did not elicit a greater attenuation than either compound alone. Furthermore, injections into BST of the α2-adrenergic receptor (α2-AR) antagonist yohimbine, but not the α1-AR antagonist 2-{[β-(4-hydroxyphenyl)ethyl]aminomethyl}-1-tetralone hydrochloride, blocked both the hcrt-1 and NE-induced inhibition of the BST cardiovascular depressors responses. Finally, injections into BST of the GABAA receptor antagonist bicuculline, but not the GABAB receptor antagonist phaclofen, blocked the hcrt-1 and NE attenuation of the BST Glu-induced depressor and bradycardia responses. These data suggest that hcrt-1 effects in BST are mediated by NE neurons, and hcrt-1 likely acts to facilitate the synaptic release of NE. NE neurons, acting through α2-AR may activate Gabaergic neurons in BST, which in turn through the activation of GABAA receptors inhibit a BST sympathoinhibitory pathway. Taken together, these data suggest that hcrt-1 pathways to BST through their interaction with NE and Gabaergic neurons may function in the coordination of cardiovascular responses associated with different behavioral states.
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Co-localization of hypocretin-1 and leucine-enkephalin in hypothalamic neurons projecting to the nucleus of the solitary tract and their effect on arterial pressure. Neuroscience 2013; 250:599-613. [PMID: 23912034 DOI: 10.1016/j.neuroscience.2013.07.054] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2013] [Revised: 07/16/2013] [Accepted: 07/18/2013] [Indexed: 01/03/2023]
Abstract
Experiments were done to investigate whether hypothalamic hypocretin-1 (hcrt-1; orexin-A) neurons that sent axonal projections to cardiovascular responsive sites in the nucleus of the solitary tract (NTS) co-expressed leucine-enkephalin (L-Enk), and to determine the effects of co-administration of hcrt-1 and D-Ala2,D-Leu5-Enkephalin (DADL) into NTS on mean arterial pressure (MAP) and heart rate. In the first series, in the Wistar rat the retrograde tract-tracer fluorogold (FG) was microinjected (50nl) into caudal NTS sites at which L-glutamate (0.25 M; 10 nl) elicited decreases in MAP and where fibers hcrt-1 immunoreactive fibers were observed that also contained L-Enk immunoreactivity. Of the number of hypothalamic hcrt-1 immunoreactive neurons identified ipsilateral to the NTS injection site (1207 ± 78), 32.3 ± 2.3% co-expressed L-Enk immunoreactivity and of these, 2.6 ± 1.1% were retrogradely labeled with FG. Hcrt-1/L-Enk neurons projecting to NTS were found mainly within the perifornical region. In the second series, the region of caudal NTS found to contain axons that co-expressed hcrt-1 and L-Enk immunoreactivity was microinjected with a combination of hcrt-1 and DADL in α-chloralose anesthetized Wistar rats. Microinjection of DADL into NTS elicited depressor and bradycardia responses similar to those elicited by microinjection of hcrt-1. An hcrt-1 injection immediately after the DADL injection elicited an almost twofold increase in the magnitude of the depressor and bradycardia responses compared to those elicited by hcrt-1 alone. Prior injections of the non-specific opioid receptor antagonist naloxone or the specific opioid δ-receptor antagonist ICI 154,129 significantly attenuated the cardiovascular responses to the combined hcrt-1-DADL injections. Taken together, these data suggest that activation of hypothalamic-opioidergic neuronal systems contribute to the NTS hcrt-1 induced cardiovascular responses, and that this descending hypothalamo-medullary pathway may represent the anatomical substrate by which hcrt-1/L-Enk neurons function in the coordination of autonomic-cardiovascular responses during different behavioral states.
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García-García B, Reinoso-Suárez F, Rodrigo-Angulo ML. Hypothalamic Hypocretinergic/Orexinergic Neurons Projecting to the Oral Pontine Rapid Eye Movement Sleep Inducing Site in the Cat. Anat Rec (Hoboken) 2013; 296:815-21. [DOI: 10.1002/ar.22690] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 12/19/2012] [Indexed: 11/06/2022]
Affiliation(s)
- Berta García-García
- Departamento de Anatomía; Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid; Madrid Spain
| | - Fernando Reinoso-Suárez
- Departamento de Anatomía; Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid; Madrid Spain
| | - Margarita L. Rodrigo-Angulo
- Departamento de Anatomía; Histología y Neurociencia, Facultad de Medicina, Universidad Autónoma de Madrid; Madrid Spain
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Dum RP, Strick PL. Transneuronal tracing with neurotropic viruses reveals network macroarchitecture. Curr Opin Neurobiol 2013; 23:245-9. [PMID: 23287632 DOI: 10.1016/j.conb.2012.12.002] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Accepted: 12/04/2012] [Indexed: 12/24/2022]
Abstract
A major challenge in systems neuroscience is to unravel the complex matrix of connections that characterize functional circuits within the central nervous system. Retrograde transneuronal transport of rabies virus has proven to be especially useful for this purpose. Here we provide specific examples in which transneuronal transport of rabies virus has been used to unravel multi-synaptic pathways within motor, cognitive and autonomic circuits. Tracing with rabies virus defined: first, the closed-loop organization of cerebellar and basal ganglia circuits with the cerebral cortex; second, the presence of bidirectional communication between the cerebellum and basal ganglia; third, the specific cortical areas that have monosynaptic and/or disynaptic connections to spinal motoneurons in non-human primates; and fourth, the areas in the cerebral cortex with the most direct influence on the sympathetic innervation of the kidney. These examples demonstrate the power of transneuronal tracing with rabies virus to identify the macroarchitecture of complex neural circuits.
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Affiliation(s)
- Richard P Dum
- Department of Neurobiology, Center for Neural Basis of Cognition, and Systems Neuroscience Institute, University of Pittsburgh School of Medicine, Pittsburgh, PA 15261, United States.
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Johnson PL, Molosh A, Fitz SD, Truitt WA, Shekhar A. Orexin, stress, and anxiety/panic states. PROGRESS IN BRAIN RESEARCH 2012; 198:133-61. [PMID: 22813973 DOI: 10.1016/b978-0-444-59489-1.00009-4] [Citation(s) in RCA: 158] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
A panic response is an adaptive response to deal with an imminent threat and consists of an integrated pattern of behavioral (aggression, fleeing, or freezing) and increased cardiorespiratory and endocrine responses that are highly conserved across vertebrate species. In the 1920s and 1940s, Philip Bard and Walter Hess, respectively, determined that the posterior regions of the hypothalamus are critical for a "fight-or-flight" reaction to deal with an imminent threat. Since the 1940s it was determined that the posterior hypothalamic panic area was located dorsal (perifornical hypothalamus: PeF) and dorsomedial (dorsomedial hypothalamus: DMH) to the fornix. This area is also critical for regulating circadian rhythms and in 1998, a novel wake-promoting neuropeptide called orexin (ORX)/hypocretin was discovered and determined to be almost exclusively synthesized in the DMH/PeF perifornical hypothalamus and adjacent lateral hypothalamus. The most proximally emergent role of ORX is in regulation of wakefulness through interactions with efferent systems that mediate arousal and energy homeostasis. A hypoactive ORX system is also linked to narcolepsy. However, ORX role in more complex emotional responses is emerging in more recent studies where ORX is linked to depression and anxiety states. Here, we review data that demonstrates ORX ability to mobilize a coordinated adaptive panic/defense response (anxiety, cardiorespiratory, and endocrine components), and summarize the evidence that supports a hyperactive ORX system being linked to pathological panic and anxiety states.
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Affiliation(s)
- Philip L Johnson
- Department of Psychiatry, Institute of Psychiatric Research, Indiana University School of Medicine, Indianapolis, Indiana, USA.
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