1
|
Ramakrishnan RK, Srivastava A, Rajan R, Abusnana S, Mussa BM. Investigating the role of an immediate early gene FOS as a potential regulator of autophagic response to hypoglycemia in embryonic hypothalamic neurons. Clin Transl Sci 2024; 17:e13749. [PMID: 38488430 PMCID: PMC10941580 DOI: 10.1111/cts.13749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/31/2024] [Accepted: 02/07/2024] [Indexed: 03/18/2024] Open
Abstract
Hypoglycemia-associated autonomic failure (HAAF) is a well-established complication of diabetes. Although HAAF has serious outcomes such as recurrent morbidity, coma, and death, the mechanisms of HAAF and its pathological components are largely unknown. Our previous studies have revealed that hypoglycemia is associated with the upregulation of an immediate early gene - FOS. In addition, it is documented that glucose deprivation activates neuronal autophagic activities. Therefore, the present study aimed to identify the role of FOS and one of the core components of the autophagy pathway, Beclin-1 (encoded by the BECN1 gene), in the regulation of autophagic mechanisms in embryonic hypothalamic neurons in response to hypoglycemic conditions. Embryonic Mouse Hypothalamic Cell Line N39 (mHypoE-N39 or N39) was cultured in reduced concentrations of glucose (2000, 900, 500, and 200 mg/L). Gene and protein expression, as well as immunofluorescence studies on autophagy were conducted under different reduced glucose concentrations in N39 hypothalamic neurons with and without FOS and BECN1 gene knockdowns (KD). The outcomes of the present study have demonstrated a significant increase in autophagosome formation and subsequent lysosomal degradation in the hypothalamic neurons in response to reduced glucose concentrations. This hypoglycemic response appears to be lowered to a similar extent in the FOS KD and BECN1 KD cells, albeit insignificantly from the negative control, is indicative of the involvement of FOS in the autophagic response of hypothalamic neurons to hypoglycemia. Moreover, the KD cells exhibited a change in morphology and reduced cell viability compared with the control cells. Our findings suggest that reduced FOS expression could potentially be associated with impaired autophagic activities that are dependent on BECN1, which could lead to decreased or blunted hypothalamic activation in response to hypoglycemia, and this, in turn, may contribute to the development of HAAF.
Collapse
Affiliation(s)
- Rakhee K. Ramakrishnan
- Research Institute for Medical and Health Sciences, College of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Ankita Srivastava
- Research Institute for Medical and Health Sciences, College of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Reeja Rajan
- Research Institute for Medical and Health Sciences, College of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Salah Abusnana
- Diabetes and Endocrinology DepartmentUniversity Hospital SharjahSharjahUnited Arab Emirates
- Clinical Science DepartmentCollege of Medicine, University of SharjahSharjahUnited Arab Emirates
| | - Bashair M. Mussa
- Basic Medical Science DepartmentCollege of Medicine, University of SharjahSharjahUnited Arab Emirates
| |
Collapse
|
2
|
Senthilkumaran M, Koch C, Herselman MF, Bobrovskaya L. Role of the Adrenal Medulla in Hypoglycaemia-Associated Autonomic Failure-A Diabetic Perspective. Metabolites 2024; 14:100. [PMID: 38392992 PMCID: PMC10890365 DOI: 10.3390/metabo14020100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 01/27/2024] [Accepted: 01/29/2024] [Indexed: 02/25/2024] Open
Abstract
Hypoglycaemia-associated autonomic failure (HAAF) is characterised by an impairment in adrenal medullary and neurogenic symptom responses following episodes of recurrent hypoglycaemia. Here, we review the status quo of research related to the regulatory mechanisms of the adrenal medulla in its response to single and recurrent hypoglycaemia in both diabetic and non-diabetic subjects with particular focus given to catecholamine synthesis, enzymatic activity, and the impact of adrenal medullary peptides. Short-term post-transcriptional modifications, particularly phosphorylation at specific residues of tyrosine hydroxylase (TH), play a key role in the regulation of catecholamine synthesis. While the effects of recurrent hypoglycaemia on catecholamine synthetic enzymes remain inconsistent, long-term changes in TH protein expression suggest species-specific responses. Adrenomedullary peptides such as neuropeptide Y (NPY), galanin, and proenkephalin exhibit altered gene and protein expression in response to hypoglycaemia, suggesting a potential role in the modulation of catecholamine secretion. Of note is NPY, since its antagonism has been shown to prevent reductions in TH protein expression. This review highlights the need for further investigation into the molecular mechanisms involved in the adrenal medullary response to hypoglycaemia. Despite advancements in our understanding of HAAF in non-diabetic rodents, a reliable diabetic rodent model of HAAF remains a challenge.
Collapse
Affiliation(s)
- Manjula Senthilkumaran
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Coen Koch
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Mauritz Frederick Herselman
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| | - Larisa Bobrovskaya
- Health and Biomedical Innovation, Clinical and Health Sciences, University of South Australia, Adelaide, SA 5000, Australia
| |
Collapse
|
3
|
Zsombok A, Desmoulins LD, Derbenev AV. Sympathetic circuits regulating hepatic glucose metabolism: where we stand. Physiol Rev 2024; 104:85-101. [PMID: 37440208 PMCID: PMC11281813 DOI: 10.1152/physrev.00005.2023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 06/12/2023] [Accepted: 07/10/2023] [Indexed: 07/14/2023] Open
Abstract
The prevalence of metabolic disorders, including type 2 diabetes mellitus, continues to increase worldwide. Although newer and more advanced therapies are available, current treatments are still inadequate and the search for solutions remains. The regulation of energy homeostasis, including glucose metabolism, involves an exchange of information between the nervous systems and peripheral organs and tissues; therefore, developing treatments to alter central and/or peripheral neural pathways could be an alternative solution to modulate whole body metabolism. Liver glucose production and storage are major mechanisms controlling glycemia, and the autonomic nervous system plays an important role in the regulation of hepatic functions. Autonomic nervous system imbalance contributes to excessive hepatic glucose production and thus to the development and progression of type 2 diabetes mellitus. At cellular levels, change in neuronal activity is one of the underlying mechanisms of autonomic imbalance; therefore, modulation of the excitability of neurons involved in autonomic outflow governance has the potential to improve glycemic status. Tissue-specific subsets of preautonomic neurons differentially control autonomic outflow; therefore, detailed information about neural circuits and properties of liver-related neurons is necessary for the development of strategies to regulate liver functions via the autonomic nerves. This review provides an overview of our current understanding of the hypothalamus-ventral brainstem-liver pathway involved in the sympathetic regulation of the liver, outlines strategies to identify organ-related neurons, and summarizes neuronal plasticity during diabetic conditions with a particular focus on liver-related neurons in the paraventricular nucleus.
Collapse
Affiliation(s)
- Andrea Zsombok
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, United States
- Tulane Brain Institute, Tulane University, New Orleans, Louisiana, United States
| | - Lucie D Desmoulins
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, United States
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, Louisiana, United States
- Tulane Brain Institute, Tulane University, New Orleans, Louisiana, United States
| |
Collapse
|
4
|
Patel V, Sarkar P, Siegel DM, Teegala SB, Hirschberg PR, Wajid H, Itani O, Routh VH. The Antinarcolepsy Drug Modafinil Reverses Hypoglycemia Unawareness and Normalizes Glucose Sensing of Orexin Neurons in Male Mice. Diabetes 2023; 72:1144-1153. [PMID: 36525384 PMCID: PMC10382647 DOI: 10.2337/db22-0639] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Accepted: 12/12/2023] [Indexed: 12/23/2022]
Abstract
Perifornical hypothalamus (PFH) orexin glucose-inhibited (GI) neurons that facilitate arousal have been implicated in hypoglycemia awareness. Mice lacking orexin exhibit narcolepsy, and orexin mediates the effect of the antinarcolepsy drug modafinil. Thus, hypoglycemia awareness may require a certain level of arousal for awareness of the sympathetic symptoms of hypoglycemia (e.g., tremors, anxiety). Recurrent hypoglycemia (RH) causes hypoglycemia unawareness. We hypothesize that RH impairs the glucose sensitivity of PFH orexin GI neurons and that modafinil normalizes glucose sensitivity of these neurons and restores hypoglycemia awareness after RH. Using patch-clamp recording, we found that RH enhanced glucose inhibition of PFH orexin GI neurons in male mice, thereby blunting activation of these neurons in low-glucose conditions. We then used a modified conditioned place preference behavioral test to demonstrate that modafinil reversed hypoglycemia unawareness in male mice after RH. Similarly, modafinil restored normal glucose sensitivity to PFH orexin GI neurons. We conclude that impaired glucose sensitivity of PFH orexin GI neurons plays a role in hypoglycemia unawareness and that normalizing their glucose sensitivity after RH is associated with restoration of hypoglycemia awareness. This suggests that the glucose sensitivity of PFH orexin GI neurons is a therapeutic target for preventing hypoglycemia unawareness.
Collapse
Affiliation(s)
- Vishwendra Patel
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers – the State University of New Jersey, Newark, NJ
| | - Pallabi Sarkar
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers – the State University of New Jersey, Newark, NJ
| | - Dashiel M. Siegel
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers – the State University of New Jersey, Newark, NJ
| | - Suraj B. Teegala
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers – the State University of New Jersey, Newark, NJ
| | - Pamela R. Hirschberg
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers – the State University of New Jersey, Newark, NJ
| | - Hamad Wajid
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers – the State University of New Jersey, Newark, NJ
| | - Omar Itani
- Federated Department of Biological Sciences, New Jersey Institute of Technology and Rutgers University-Newark, Newark, NJ
| | - Vanessa H. Routh
- Department of Pharmacology, Physiology and Neuroscience, New Jersey Medical School, Rutgers – the State University of New Jersey, Newark, NJ
| |
Collapse
|
5
|
Tapia GP, Agostinelli LJ, Chenausky SD, Padilla JVS, Navarro VI, Alagh A, Si G, Thompson RH, Balivada S, Khan AM. Glycemic Challenge Is Associated with the Rapid Cellular Activation of the Locus Ceruleus and Nucleus of Solitary Tract: Circumscribed Spatial Analysis of Phosphorylated MAP Kinase Immunoreactivity. J Clin Med 2023; 12:2483. [PMID: 37048567 PMCID: PMC10095283 DOI: 10.3390/jcm12072483] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 02/24/2023] [Accepted: 03/02/2023] [Indexed: 03/31/2023] Open
Abstract
Rodent studies indicate that impaired glucose utilization or hypoglycemia is associated with the cellular activation of neurons in the medulla (Winslow, 1733) (MY), believed to control feeding behavior and glucose counterregulation. However, such activation has been tracked primarily within hours of the challenge, rather than sooner, and has been poorly mapped within standardized brain atlases. Here, we report that, within 15 min of receiving 2-deoxy-d-glucose (2-DG; 250 mg/kg, i.v.), which can trigger glucoprivic feeding behavior, marked elevations were observed in the numbers of rhombic brain (His, 1893) (RB) neuronal cell profiles immunoreactive for the cellular activation marker(s), phosphorylated p44/42 MAP kinases (phospho-ERK1/2), and that some of these profiles were also catecholaminergic. We mapped their distributions within an open-access rat brain atlas and found that 2-DG-treated rats (compared to their saline-treated controls) displayed greater numbers of phospho-ERK1/2+ neurons in the locus ceruleus (Wenzel and Wenzel, 1812) (LC) and the nucleus of solitary tract (>1840) (NTS). Thus, the 2-DG-activation of certain RB neurons is more rapid than perhaps previously realized, engaging neurons that serve multiple functional systems and which are of varying cellular phenotypes. Mapping these populations within standardized brain atlas maps streamlines their targeting and/or comparable mapping in preclinical rodent models of disease.
Collapse
Affiliation(s)
- Geronimo P. Tapia
- UTEP Systems Neuroscience Laboratory, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
- Ph.D. Program in Bioscience, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Lindsay J. Agostinelli
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Sarah D. Chenausky
- UTEP Systems Neuroscience Laboratory, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
- M.S. Program in Biology, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Jessica V. Salcido Padilla
- UTEP Systems Neuroscience Laboratory, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
- M.S. Program in Biology, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Vanessa I. Navarro
- UTEP Systems Neuroscience Laboratory, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
- Ph.D. Program in Bioscience, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Amy Alagh
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Gabriel Si
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
| | - Richard H. Thompson
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
- School of Information, The University of Texas at Austin, Austin, TX 78701, USA
| | - Sivasai Balivada
- UTEP Systems Neuroscience Laboratory, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
| | - Arshad M. Khan
- UTEP Systems Neuroscience Laboratory, Department of Biological Sciences, The University of Texas at El Paso, El Paso, TX 79968, USA
- Department of Biological Sciences, University of Southern California, Los Angeles, CA 90089, USA
- Border Biomedical Research Center, The University of Texas at El Paso, El Paso, TX 79968, USA
| |
Collapse
|
6
|
Cai Y, Li X, Zhou H, Zhou J. The serotonergic system dysfunction in diabetes mellitus. Front Cell Neurosci 2022; 16:899069. [PMID: 35910256 PMCID: PMC9331500 DOI: 10.3389/fncel.2022.899069] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 06/27/2022] [Indexed: 11/13/2022] Open
Abstract
Most peripheral serotonin (5-HT) is synthesized in enterochromaffin cells, and most circulating 5-HT is stored in platelets. As a monoamine, 5-HT has several functions in various non-neuronal and neuronal systems. In the central nervous system, it functions as a neurotransmitter to modulate feeding behavior and mood. Numerous clinical trials have focused on increasing 5-HT activation in the central nervous system, including those involving anti-obesity drugs currently in the market, although severe side effects on peripheral system can lead to the withdrawal of certain drugs. Recent studies have revealed that both the peripheral and central serotonergic systems play a vital role in diabetes and its complications. This review summarizes the roles of the serotonergic system in blood glucose regulation, diabetic macroangiopathy, diabetic peripheral neuropathy, and diabetic encephalopathy, indicating its potential clinical significance as a therapeutic target for the treatment of diabetes and its complications.
Collapse
|
7
|
Verberne AJM, Mussa BM. Neural control of pancreatic peptide hormone secretion. Peptides 2022; 152:170768. [PMID: 35189258 DOI: 10.1016/j.peptides.2022.170768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/10/2022] [Accepted: 02/12/2022] [Indexed: 11/20/2022]
Abstract
Pancreatic peptide hormone secretion is inextricably linked to maintenance of normal levels of blood glucose. In animals and man, pancreatic peptide hormone secretion is controlled, at least in part, by input from parasympathetic (vagal) premotor neurons that are found principally in the dorsal motor nucleus of the vagus (DMV). Iatrogenic (insulin-induced) hypoglycaemia evokes a homeostatic response commonly referred to as the glucose counter-regulatory response. This homeostatic response is of particular importance in Type 1 diabetes in which episodes of hypoglycaemia are common, debilitating and lead to suboptimal control of blood glucose. Glucagon is the principal counterregulatory hormone but for reasons unknown, its secretion during insulin-induced hypoglycaemia is impaired. Pancreatic parasympathetic neurons are distinguishable electrophysiologically from those that control other (e.g. gastric) functions and are controlled by supramedullary inputs from hypothalamic structures such as the perifornical region. During hypoglycaemia, glucose-sensitive, GABAergic neurons in the ventromedial hypothalamus are inhibited leading to disinhibition of perifornical orexin neurons with projections to the DMV which, in turn, leads to increased secretion of glucagon.
Collapse
Affiliation(s)
- Anthony J M Verberne
- Department of Medicine, University of Melbourne, Austin Health, Heidelberg, Victoria 3084, Australia.
| | - Bashair M Mussa
- Basic Medical Science Department, College of Medicine, University of Sharjah, Sharjah 27272, United Arab Emirates
| |
Collapse
|
8
|
Koracevic G, Micic S, Stojanovic M, Radovanovic RV, Pavlovic MP, Kostic T, Djordjevic D, Antonijevic N, Koracevic M, Atanaskovic V, Dakic S. Beta Blockers can mask not only Hypoglycemia, but also Hypotension. Curr Pharm Des 2022; 28:1660-1668. [DOI: 10.2174/1381612828666220421135523] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 02/01/2022] [Indexed: 11/22/2022]
Abstract
Background:
Beta-adrenergic (β-AR) receptor blockers (BBs) are an essential class of drugs as they have numerous indications. On the other hand, they have numerous unwanted effects which decrease the compliance, adherence, and persistence of this very useful group of drugs.
Objective:
The paper aims to analyze the possibility that an unnoticed side effect may contribute to a less favorable pharmacologic profile of BBs, e.g., a diminished reaction to a sudden fall in BP.
Methods:
We searched two medical databases for abstracts and citations (Medline and SCOPUS). Moreover, we searched the internet for drug prescription leaflets (of the individual BBs).
Results:
Whichever cause of stress is considered, the somatic manifestations of stress will be (partially) masked if a patient takes BB. Stress–induced hypercatecholaminemia acts on β-AR of cardiomyocytes; it increases heart rate and contractility, effects suppressed by BBs. The answers of the organism to hypoglycemia and hypotension share the main mechanisms such as sympathetic nervous system activation and hypercatecholaminemia. Thus, there is a striking analogy: BBs can cover up symptoms of both hypoglycemia (which is widely known) and of hypotension (which is not recognized). It is widely known that BBs can cause hypotension. However, they can also complicate recovery by spoiling the defense mechanisms in hypotension as they interfere with the crucial compensatory reflex to increase blood pressure in hypotension.
Conclusion:
Beta blockers can cause hypotension, mask it, and make recovery more difficult. This is clinically important and deserves to be more investigated and probably to be stated as a warning.
Collapse
Affiliation(s)
- Goran Koracevic
- Department for Cardiovascular Diseases, University Clinical Centre Nis, Nis, Serbia
| | | | | | | | - Milan Pavlovic Pavlovic
- Department for Cardiovascular Diseases, University Clinical Centre Nis, Nis, Serbia
- Faculty of Medicine, University of Nis, Nis, Serbia
| | - Tomislav Kostic
- Department for Cardiovascular Diseases, University Clinical Centre Nis, Nis, Serbia
- Faculty of Medicine, University of Nis, Nis, Serbia
| | - Dragan Djordjevic
- Faculty of Medicine, University of Nis, Nis, Serbia
- Institute for Treatment and Rehabilitation Niska Banja, Nis, Serbia
| | - Nebojsa Antonijevic
- Clinic for Cardiology, University Clinical Centre of Serbia, Belgrade, Serbia
| | - Maja Koracevic
- Faculty of Medicine, University of Nis, Nis, Serbia
- Innovation Centre, University of Nis, Nis, Serbia
| | - Vesna Atanaskovic
- Department for Cardiovascular Diseases, University Clinical Centre Nis, Nis, Serbia
| | - Sonja Dakic
- Department for Cardiovascular Diseases, University Clinical Centre Nis, Nis, Serbia
| |
Collapse
|
9
|
Rivas M, Serantes D, Peña F, González J, Ferreira A, Torterolo P, Benedetto L. Role of Hypocretin in the Medial Preoptic Area in the Regulation of Sleep, Maternal Behavior and Body Temperature of Lactating Rats. Neuroscience 2021; 475:148-162. [PMID: 34500018 DOI: 10.1016/j.neuroscience.2021.08.034] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 08/23/2021] [Accepted: 08/29/2021] [Indexed: 12/11/2022]
Abstract
Hypocretins (HCRT), also known as orexins, includes two neuroexcitatory peptides, HCRT-1 and HCRT-2 (orexin A y B, respectively), synthesized by neurons located in the postero-lateral hypothalamus, whose projections and receptors are widely distributed throughout the brain, including the medial preoptic area (mPOA). HCRT have been associated with a wide range of physiological functions including sleep-wake cycle, maternal behavior and body temperature, all regulated by the mPOA. Previously, we showed that HCRT in the mPOA facilitates certain active maternal behaviors, while the blockade of HCRT-R1 increases the time spent in nursing. As mother rats mainly sleep while they nurse, we hypothesize that HCRT in the mPOA of lactating rats reduce sleep and nursing, while intra-mPOA administration of a dual orexin receptor antagonist (DORA) would cause the opposite effect. Therefore, the aim of this study was to determine the role of HCRT within the mPOA, in the regulation and integration of the sleep-wake cycle, maternal behavior and body temperature of lactating rats. For that purpose, we assessed the sleep-wake states, maternal behavior and body temperature of lactating rats following microinjections of HCRT-1 (100 and 200 µM) and DORA (5 mM) into the mPOA. As expected, our data show that HCRT-1 in mPOA promote wakefulness and a slightly increase in body temperature, whereas DORA increases both NREM and REM sleep together with an increment of nursing and milk ejection. Taken together, our results strongly suggest that the endogenous reduction of HCRT within the mPOA contribute to the promotion of sleep, milk ejection and nursing behavior in lactating rats.
Collapse
Affiliation(s)
- Mayda Rivas
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Diego Serantes
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Florencia Peña
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Joaquín González
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Annabel Ferreira
- Sección de Fisiología y Nutrición, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Pablo Torterolo
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay
| | - Luciana Benedetto
- Departamento de Fisiología, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
| |
Collapse
|
10
|
Slow but Steady-The Responsiveness of Sympathoadrenal System to a Hypoglycemic Challenge in Ketogenic Diet-Fed Rats. Nutrients 2021; 13:nu13082627. [PMID: 34444787 PMCID: PMC8398867 DOI: 10.3390/nu13082627] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 07/25/2021] [Accepted: 07/28/2021] [Indexed: 12/16/2022] Open
Abstract
The sympathoadrenal counterregulatory response to hypoglycemia is critical for individuals with type 1 diabetes due to impaired ability to produce glucagon. Ketogenic diets (KD) are an increasingly popular diabetes management tool; however, the effects of KD on the sympathoadrenal response are largely unknown. Here, we determined the effects of KD-induced ketosis on the sympathoadrenal response to a single insulin-induced hypoglycemic challenge. We investigated how a 3 week KD feeding regimen affected the main components of the sympathoadrenal counterregulatory response: adrenal sympathetic nerve activity (ASNA), adrenal gland activity, plasma epinephrine, and brainstem glucose-responsive C1 neuronal activation in anesthetized, nondiabetic male Sprague-Dawley rats. Rats on KD had similar blood glucose (BG) levels and elevated ketone body β-hydroxybutyrate (BHB) levels compared to the control Chow diet group. All KD rats responded to hypoglycemia with a robust increase in ASNA, which was initiated at significantly lower BG levels compared to Chow-fed rats. The delay in hypoglycemia-induced ASNA increase was concurrent with rapid disappearance of BHB from cerebral and peripheral circulation. Adrenal gland activity paralleled epinephrine and ASNA response. Overall, KD-induced ketosis was associated with initiation of the sympathoadrenal response at lower blood glucose levels; however, the magnitude of the response was not diminished.
Collapse
|
11
|
Garcia SM, Hirschberg PR, Sarkar P, Siegel DM, Teegala SB, Vail GM, Routh VH. Insulin actions on hypothalamic glucose-sensing neurones. J Neuroendocrinol 2021; 33:e12937. [PMID: 33507001 PMCID: PMC10561189 DOI: 10.1111/jne.12937] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Revised: 12/22/2020] [Accepted: 12/29/2020] [Indexed: 12/13/2022]
Abstract
Subsequent to the discovery of insulin 100 years ago, great strides have been made in understanding its function, especially in the brain. It is now clear that insulin is a critical regulator of the neuronal circuitry controlling energy balance and glucose homeostasis. This review focuses on the effects of insulin and diabetes on the activity and glucose sensitivity of hypothalamic glucose-sensing neurones. We highlight the role of electrophysiological data in understanding how insulin regulates glucose-sensing neurones. A brief introduction describing the benefits and limitations of the major electrophysiological techniques used to investigate glucose-sensing neurones is provided. The mechanisms by which hypothalamic neurones sense glucose are discussed with an emphasis on those glucose-sensing neurones already shown to be modulated by insulin. Next, the literature pertaining to how insulin alters the activity and glucose sensitivity of these hypothalamic glucose-sensing neurones is described. In addition, the effects of impaired insulin signalling during diabetes and the ramifications of insulin-induced hypoglycaemia on hypothalamic glucose-sensing neurones are covered. To the extent that it is known, we present hypotheses concerning the mechanisms underlying the effects of these insulin-related pathologies. To conclude, electrophysiological data from the hippocampus are evaluated aiming to provide clues regarding how insulin might influence neuronal plasticity in glucose-sensing neurones. Although much has been accomplished subsequent to the discovery of insulin, the work described in our review suggests that the regulation of central glucose sensing by this hormone is both important and understudied.
Collapse
Affiliation(s)
- Stephanie M Garcia
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Pamela R Hirschberg
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Pallabi Sarkar
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Dashiel M Siegel
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Suraj B Teegala
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Gwyndolin M Vail
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neuroscience, Rutgers, New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| |
Collapse
|
12
|
Seoane-Collazo P, Diéguez C, Nogueiras R, Rahmouni K, Fernández-Real JM, López M. Nicotine' actions on energy balance: Friend or foe? Pharmacol Ther 2020; 219:107693. [PMID: 32987056 DOI: 10.1016/j.pharmthera.2020.107693] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 09/21/2020] [Indexed: 12/12/2022]
Abstract
Obesity has reached pandemic proportions and is associated with severe comorbidities, such as type 2 diabetes mellitus, hepatic and cardiovascular diseases, and certain cancer types. However, the therapeutic options to treat obesity are limited. Extensive epidemiological studies have shown a strong relationship between smoking and body weight, with non-smokers weighing more than smokers at any age. Increased body weight after smoking cessation is a major factor that interferes with their attempts to quit smoking. Numerous controlled studies in both humans and rodents have reported that nicotine, the main bioactive component of tobacco, exerts a marked anorectic action. Furthermore, nicotine is also known to modulate energy expenditure, by regulating the thermogenic activity of brown adipose tissue (BAT) and the browning of white adipose tissue (WAT), as well as glucose homeostasis. Many of these actions occur at central level, by controlling the activity of hypothalamic neuropeptide systems such as proopiomelanocortin (POMC), or energy sensors such as AMP-activated protein kinase (AMPK). However, direct impact of nicotine on metabolic tissues, such as BAT, WAT, liver and pancreas has also been described. Here, we review the actions of nicotine on energy balance. The relevance of this interaction is interesting, because considering the restricted efficiency of obesity treatments, a possible complementary approach may focus on compounds with known pharmacokinetic profile and pharmacological actions, such as nicotine or nicotinic acetylcholine receptors signaling.
Collapse
Affiliation(s)
- Patricia Seoane-Collazo
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain; International Institute for Integrative Sleep Medicine (WPI-IIIS), University of Tsukuba, Tsukuba, Ibaraki 305-8575, Japan.
| | - Carlos Diéguez
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Rubén Nogueiras
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain
| | - Kamal Rahmouni
- Department of Neuroscience and Pharmacology, University of Iowa Carver College of Medicine and Veterans Affairs Health Care System, Iowa City, IA 52242, USA
| | - José Manuel Fernández-Real
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain; Institut d'Investigació Biomèdica de Girona (IDIBGI), Girona, Spain; Department of Diabetes, Endocrinology and Nutrition (UDEN), Hospital of Girona "Dr Josep Trueta" and Department of Medical Sciences, Faculty of Medicine, University of Girona, Girona, Spain
| | - Miguel López
- Department of Physiology, CIMUS, University of Santiago de Compostela-Instituto de Investigación Sanitaria, Santiago de Compostela 15782, Spain; CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn), 15706, Spain.
| |
Collapse
|
13
|
Sankar A, Khodai T, McNeilly AD, McCrimmon RJ, Luckman SM. Experimental Models of Impaired Hypoglycaemia-Associated Counter-Regulation. Trends Endocrinol Metab 2020; 31:691-703. [PMID: 32563715 DOI: 10.1016/j.tem.2020.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 05/14/2020] [Accepted: 05/26/2020] [Indexed: 01/24/2023]
Abstract
Impaired awareness of hypoglycaemia (IAH) affects around a quarter of patients with diabetes who receive insulin treatment. This condition is characterised by a progressive reduction in symptomatic and behavioural responses to hypoglycaemia, increasing risk of deeper drops in blood glucose, unconsciousness, and collapse. Thus, patients with IAH experience severe hypoglycaemic episodes more frequently, resulting in significant morbidity and mortality. IAH is thought to develop as a consequence of whole-body adaptations to repeated insulin-induced hypoglycaemia (RH), with widespread deficits in the hypoglycaemia counter-regulatory response (CRR). Despite this important insight, the precise pathophysiology by which RH leads to an attenuated CRR is unknown. Studies into the underlying mechanisms of IAH have employed a variety of protocols in humans and experimental species. The use of animal models has many investigational benefits, including the unprecedented increase in the availability of transgenic strains. However, modelling impaired hypoglycaemia-associated counter-regulation remains challenging and appropriate interpretation of findings across species and protocols even more so. Here, we review the experimental modelling of IAH and impaired hypoglycaemia-associated counter-regulation, with a focus on understanding species-specific variation in glucose homeostasis. This review will aid investigators in interpreting outputs from different studies in IAH and aid progress in the field.
Collapse
Affiliation(s)
- Adhithya Sankar
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Tansi Khodai
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Alison D McNeilly
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Rory J McCrimmon
- Division of Systems Medicine, School of Medicine, University of Dundee, Dundee, UK
| | - Simon M Luckman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK.
| |
Collapse
|
14
|
Hirschberg PR, Sarkar P, Teegala SB, Routh VH. Ventromedial hypothalamus glucose-inhibited neurones: A role in glucose and energy homeostasis? J Neuroendocrinol 2020; 32:e12773. [PMID: 31329314 PMCID: PMC7074896 DOI: 10.1111/jne.12773] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/01/2019] [Revised: 06/18/2019] [Accepted: 07/14/2019] [Indexed: 12/20/2022]
Abstract
The ventromedial hypothalamus (VMH) plays a complex role in glucose and energy homeostasis. The VMH is necessary for the counter-regulatory response to hypoglycaemia (CRR) that increases hepatic gluconeogenesis to restore euglycaemia. On the other hand, the VMH also restrains hepatic glucose production during euglycaemia and stimulates peripheral glucose uptake. The VMH is also important for the ability of oestrogen to increase energy expenditure. This latter function is mediated by VMH modulation of the lateral/perifornical hypothalamic area (lateral/perifornical hypothalamus) orexin neurones. Activation of VMH AMP-activated protein kinase (AMPK) is necessary for the CRR. By contrast, VMH AMPK inhibition favours decreased basal glucose levels and is required for oestrogen to increase energy expenditure. Specialised VMH glucose-sensing neurones confer the ability to sense and respond to changes in blood glucose levels. Glucose-excited (GE) neurones increase and glucose-inhibited (GI) neurones decrease their activity as glucose levels rise. VMH GI neurones, in particular, appear to be important in the CRR, although a role for GE neurones cannot be discounted. AMPK mediates glucose sensing in VMH GI neurones suggesting that, although activation of these neurones is important for the CRR, it is necessary to silence them to lower basal glucose levels and enable oestrogen to increase energy expenditure. In support of this, we found that oestrogen reduces activation of VMH GI neurones in low glucose by inhibiting AMPK. In this review, we present the evidence underlying the role of the VMH in glucose and energy homeostasis. We then discuss the role of VMH glucose-sensing neurones in mediating these effects, with a strong emphasis on oestrogenic regulation of glucose sensing and how this may affect glucose and energy homeostasis.
Collapse
Affiliation(s)
- Pamela R Hirschberg
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Pallabi Sarkar
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Suraj B Teegala
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| | - Vanessa H Routh
- Department of Pharmacology, Physiology and Neurosciences, Rutgers New Jersey Medical School, The State University of New Jersey, Newark, NJ, USA
| |
Collapse
|
15
|
Mussa BM, Taneera J, Mohammed AK, Srivastava A, Mukhopadhyay D, Sulaiman N. Potential role of hypothalamic microRNAs in regulation of FOS and FTO expression in response to hypoglycemia. J Physiol Sci 2019; 69:981-991. [PMID: 31728912 PMCID: PMC10717546 DOI: 10.1007/s12576-019-00718-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2019] [Accepted: 10/06/2019] [Indexed: 01/05/2023]
Abstract
Hypoglycemia-associated autonomic failure (HAAF) is a serious complication of diabetes which is associated with the absence of physiological homeostatic counter-regulatory mechanisms that are controlled by the hypothalamus and sympathetic nervous system. Identification of biomarkers for early detection of HAAF requires an advanced understanding of molecular signature of hypoglycemia which is yet to be identified. The outcomes of the present study have shown that the viability and the apoptotic rate of the hypothalamic neurons (mHypoE-N39) were decreased significantly due to hypoglycemia in a dose-dependent fashion (p < 0.05). Although there are more than 1000 miRNAs differentially expressed in hypothalamus, only twelve miRNAs (miR-7a, miR-7b, miR-9, miR-29b, miR-29c, miR-30a, miR-30b, miR-30c, miR-101b-3p, miR-181a-5p, miR-378-3p and miR-873-5p) were correlated to two main hypothalamic regulatory proteins, FOS and FTO. Expression of these proteins was very sensitive to hypoglycemia. We demonstrated that hypoglycemia modulates the expression of hypothalamic miRNAs that are related to FOS and FTO.
Collapse
Affiliation(s)
- Bashair M Mussa
- Basic Medical Science Department, College of Medicine, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates.
| | - Jalal Taneera
- Basic Medical Science Department, College of Medicine, Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Abdul Khader Mohammed
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Ankita Srivastava
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Debasmita Mukhopadhyay
- Sharjah Institute for Medical Research, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| | - Nabil Sulaiman
- Family Medicine and Behavioral Science, College of Medicine, University of Sharjah, P.O. Box: 27272, Sharjah, United Arab Emirates
| |
Collapse
|
16
|
Ritter S, Li AJ, Wang Q. Hindbrain glucoregulatory mechanisms: Critical role of catecholamine neurons in the ventrolateral medulla. Physiol Behav 2019; 208:112568. [PMID: 31173784 PMCID: PMC7015674 DOI: 10.1016/j.physbeh.2019.112568] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 06/03/2019] [Accepted: 06/03/2019] [Indexed: 12/29/2022]
Abstract
Glucose is the required metabolic substrate for the brain. Yet the brain stores very little glucose. Therefore, the brain continuously monitors glucose availability to detect hypoglycemia and to mobilize system-wide responses to protect and restore euglycemia. Catecholamine (CA) neurons in the hindbrain are critical elements of the brain's glucoregulatory mechanisms. They project widely throughout the brain and spinal cord, innervating sites controlling behavioral, endocrine and visceral responses. Hence, CA neurons are capable of triggering a rapid, coordinated and multifaceted response to glucose challenge. This article reviews experimental data that has begun to elucidate the importance of CA neurons for glucoregulation, the functions of specific CA subpopulations in the ventrolateral medulla, and the extended circuitry through which they engage other levels of the nervous system to accomplish their essential glucoregulatory task. Hopefully, this review also suggests the vast amount of work yet to be done in this area and the justification for engaging in that effort.
Collapse
Affiliation(s)
- Sue Ritter
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, United States of America.
| | - Ai-Jun Li
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, United States of America
| | - Qing Wang
- Department of Integrative Physiology and Neuroscience, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, United States of America
| |
Collapse
|
17
|
Saleeba C, Dempsey B, Le S, Goodchild A, McMullan S. A Student's Guide to Neural Circuit Tracing. Front Neurosci 2019; 13:897. [PMID: 31507369 PMCID: PMC6718611 DOI: 10.3389/fnins.2019.00897] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/12/2019] [Indexed: 12/17/2022] Open
Abstract
The mammalian nervous system is comprised of a seemingly infinitely complex network of specialized synaptic connections that coordinate the flow of information through it. The field of connectomics seeks to map the structure that underlies brain function at resolutions that range from the ultrastructural, which examines the organization of individual synapses that impinge upon a neuron, to the macroscopic, which examines gross connectivity between large brain regions. At the mesoscopic level, distant and local connections between neuronal populations are identified, providing insights into circuit-level architecture. Although neural tract tracing techniques have been available to experimental neuroscientists for many decades, considerable methodological advances have been made in the last 20 years due to synergies between the fields of molecular biology, virology, microscopy, computer science and genetics. As a consequence, investigators now enjoy an unprecedented toolbox of reagents that can be directed against selected subpopulations of neurons to identify their efferent and afferent connectomes. Unfortunately, the intersectional nature of this progress presents newcomers to the field with a daunting array of technologies that have emerged from disciplines they may not be familiar with. This review outlines the current state of mesoscale connectomic approaches, from data collection to analysis, written for the novice to this field. A brief history of neuroanatomy is followed by an assessment of the techniques used by contemporary neuroscientists to resolve mesoscale organization, such as conventional and viral tracers, and methods of selecting for sub-populations of neurons. We consider some weaknesses and bottlenecks of the most widely used approaches for the analysis and dissemination of tracing data and explore the trajectories that rapidly developing neuroanatomy technologies are likely to take.
Collapse
Affiliation(s)
- Christine Saleeba
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
- The School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, United Kingdom
| | - Bowen Dempsey
- CNRS, Hindbrain Integrative Neurobiology Laboratory, Neuroscience Paris-Saclay Institute (Neuro-PSI), Université Paris-Saclay, Gif-sur-Yvette, France
| | - Sheng Le
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Ann Goodchild
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Simon McMullan
- Neurobiology of Vital Systems Node, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| |
Collapse
|
18
|
Kakall ZM, Kavurma MM, Cohen EM, Howe PR, Nedoboy PE, Pilowsky PM. Repetitive hypoglycemia reduces activation of glucose-responsive neurons in C1 and C3 medullary brain regions to subsequent hypoglycemia. Am J Physiol Endocrinol Metab 2019; 317:E388-E398. [PMID: 31013147 PMCID: PMC6732467 DOI: 10.1152/ajpendo.00051.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Revised: 04/16/2019] [Accepted: 04/16/2019] [Indexed: 02/06/2023]
Abstract
The impaired ability of the autonomic nervous system to respond to hypoglycemia is termed "hypoglycemia-associated autonomic failure" (HAAF). This life-threatening phenomenon results from at least two recent episodes of hypoglycemia, but the pathology underpinning HAAF remains largely unknown. Although naloxone appears to improve hypoglycemia counterregulation under controlled conditions, hypoglycemia prevention remains the current mainstay therapy for HAAF. Epinephrine-synthesizing neurons in the rostroventrolateral (C1) and dorsomedial (C3) medulla project to the subset of sympathetic preganglionic neurons that regulate peripheral epinephrine release. Here we determined whether or not C1 and C3 neuronal activation is impaired in HAAF and whether or not 1 wk of hypoglycemia prevention or treatment with naloxone could restore C1 and C3 neuronal activation and improve HAAF. Twenty male Sprague-Dawley rats (250-300 g) were used. Plasma epinephrine levels were significantly increased after a single episode of hypoglycemia (n = 4; 5,438 ± 783 pg/ml vs. control 193 ± 27 pg/ml, P < 0.05). Repeated hypoglycemia significantly reduced the plasma epinephrine response to subsequent hypoglycemia (n = 4; 2,179 ± 220 pg/ml vs. 5,438 ± 783 pg/ml, P < 0.05). Activation of medullary C1 (n = 4; 50 ± 5% vs. control 3 ± 1%, P < 0.05) and C3 (n = 4; 45 ± 5% vs. control 4 ± 1%, P < 0.05) neurons was significantly increased after a single episode of hypoglycemia. Activation of C1 (n = 4; 12 ± 3%, P < 0.05) and C3 (n = 4; 19 ± 5%, P < 0.05) neurons was significantly reduced in the HAAF groups. Hypoglycemia prevention or treatment with naloxone did not restore the plasma epinephrine response or C1 and C3 neuronal activation. Thus repeated hypoglycemia reduced the activation of C1 and C3 neurons mediating adrenal medullary responses to subsequent bouts of hypoglycemia.
Collapse
Affiliation(s)
- Zohra M Kakall
- The Heart Research Institute, Newtown, New South Wales, Australia
- Department of Physiology, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Mary M Kavurma
- The Heart Research Institute, Newtown, New South Wales, Australia
- Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - E Myfanwy Cohen
- The Heart Research Institute, Newtown, New South Wales, Australia
- Department of Physiology, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Peter R Howe
- School of Biomedical Sciences and Pharmacy, University of Newcastle and Institute for Resilient Regions, University of Southern Queensland, Springfield, Queensland, Australia
| | - Polina E Nedoboy
- The Heart Research Institute, Newtown, New South Wales, Australia
- Department of Physiology, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| | - Paul M Pilowsky
- Department of Physiology, Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia
| |
Collapse
|
19
|
Integration of hindbrain and carotid body mechanisms that control the autonomic response to cardiorespiratory and glucoprivic insults. Respir Physiol Neurobiol 2019; 265:83-91. [DOI: 10.1016/j.resp.2018.08.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 08/01/2018] [Accepted: 08/29/2018] [Indexed: 01/08/2023]
|
20
|
Farmer DGS, Pracejus N, Dempsey B, Turner A, Bokiniec P, Paton JFR, Pickering AE, Burguet J, Andrey P, Goodchild AK, McAllen RM, McMullan S. On the presence and functional significance of sympathetic premotor neurons with collateralized spinal axons in the rat. J Physiol 2019; 597:3407-3423. [DOI: 10.1113/jp277661] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2019] [Accepted: 04/23/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- David G. S. Farmer
- Florey Institute of Neuroscience and Mental Health University of Melbourne Parkville VIC Australia
| | - Natasha Pracejus
- Florey Institute of Neuroscience and Mental Health University of Melbourne Parkville VIC Australia
| | - Bowen Dempsey
- Neuroscience Paris‐Saclay Institute (Neuro‐PSI) CNRS Gif‐Sur‐Yvette France
| | - Anita Turner
- Faculty of Medicine & Health Science Macquarie University North Ryde NSW Australia
| | - Phillip Bokiniec
- Department of Neuroscience Max Delbrück Center for Molecular Medicine (MDC) Berlin‐Buch, Germany Neuroscience Research Center and Cluster of Excellence NeuroCure Charité‐Universitätsmedizin Berlin Germany
| | - Julian F. R. Paton
- Department of Physiology Faculty of Medical & Health Sciences University of Auckland Park Road Grafton Auckland New Zealand
| | - Anthony E. Pickering
- School of Physiology, Pharmacology & Neuroscience, Biomedical Sciences University of Bristol Bristol UK
| | - Jasmine Burguet
- Institut Jean‐Pierre Bourgin INRA AgroParisTech CNRS Université Paris‐Saclay Versailles France
| | - Philippe Andrey
- Institut Jean‐Pierre Bourgin INRA AgroParisTech CNRS Université Paris‐Saclay Versailles France
| | - Ann K. Goodchild
- Faculty of Medicine & Health Science Macquarie University North Ryde NSW Australia
| | - Robin M. McAllen
- Florey Institute of Neuroscience and Mental Health University of Melbourne Parkville VIC Australia
| | - Simon McMullan
- Faculty of Medicine & Health Science Macquarie University North Ryde NSW Australia
| |
Collapse
|
21
|
Gao H, Korim WS, Yao ST, Heesch CM, Derbenev AV. Glycinergic neurotransmission in the rostral ventrolateral medulla controls the time course of baroreflex-mediated sympathoinhibition. J Physiol 2018; 597:283-301. [PMID: 30312491 DOI: 10.1113/jp276467] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Accepted: 10/11/2018] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS To maintain appropriate blood flow to various tissues of the body under a variety of physiological states, autonomic nervous system reflexes regulate regional sympathetic nerve activity and arterial blood pressure. Our data obtained in anaesthetized rats revealed that glycine released in the rostral ventrolateral medulla (RVLM) plays a critical role in maintaining arterial baroreflex sympathoinhibition. Manipulation of brainstem nuclei with known inputs to the RVLM (nucleus tractus solitarius and caudal VLM) unmasked tonic glycinergic inhibition in the RVLM. Whole-cell, patch clamp recordings demonstrate that both GABA and glycine inhibit RVLM neurons. Potentiation of neurotransmitter release from the active synaptic inputs in the RVLM produced saturation of GABAergic inhibition and emergence of glycinergic inhibition. Our data suggest that GABA controls threshold excitability, wherreas glycine increases the strength of inhibition under conditions of increased synaptic activity within the RVLM. ABSTRACT The arterial baroreflex is a rapid negative-feedback system that compensates changes in blood pressure by adjusting the output of presympathetic neurons in the rostral ventrolateral medulla (RVLM). GABAergic projections from the caudal VLM (CVLM) provide a primary inhibitory input to presympathetic RVLM neurons. Although glycine-dependent regulation of RVLM neurons has been proposed, its role in determining RVLM excitability is ill-defined. The present study aimed to determine the physiological role of glycinergic neurotransmission in baroreflex function, identify the mechanisms for glycine release, and evaluate co-inhibition of RVLM neurons by GABA and glycine. Microinjection of the glycine receptor antagonist strychnine (4 mm, 100 nL) into the RVLM decreased the duration of baroreflex-mediated inhibition of renal sympathetic nerve activity (control = 12 ± 1 min; RVLM-strychnine = 5.1 ± 1 min), suggesting that RVLM glycine plays a critical role in regulating the time course of sympathoinhibition. Blockade of output from the nucleus tractus solitarius and/or disinhibition of the CVLM unmasked tonic glycinergic inhibition of the RVLM. To evaluate cellular mechanisms, RVLM neurons were retrogradely labelled (prior injection of pseudorabies virus PRV-152) and whole-cell, patch clamp recordings were obtained in brainstem slices. Under steady-state conditions GABAergic inhibition of RVLM neurons predominated and glycine contributed less than 25% of the overall inhibition. By contrast, stimulation of synaptic inputs in the RVLM decreased GABAergic inhibition to 53%; and increased glycinergic inhibition to 47%. Thus, under conditions of increased synaptic activity in the RVLM, glycinergic inhibition is recruited to strengthen sympathoinhibition.
Collapse
Affiliation(s)
- Hong Gao
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, USA
| | - Willian S Korim
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Song T Yao
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Cheryl M Heesch
- Department of Biomedical Sciences, Dalton Cardiovascular Research Center, University of Missouri, Columbia, MO, USA
| | - Andrei V Derbenev
- Department of Physiology, School of Medicine, Tulane University, New Orleans, LA, USA.,Brain Institute, Tulane University, New Orleans, LA, USA
| |
Collapse
|
22
|
Senthilkumaran M, Bobrovskaya L, Verberne AJM, Llewellyn-Smith IJ. Insulin-responsive autonomic neurons in rat medulla oblongata. J Comp Neurol 2018; 526:2665-2682. [PMID: 30136719 DOI: 10.1002/cne.24523] [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: 08/06/2017] [Revised: 08/12/2018] [Accepted: 08/15/2018] [Indexed: 11/11/2022]
Abstract
Low blood glucose activates brainstem adrenergic and cholinergic neurons, driving adrenaline secretion from the adrenal medulla and glucagon release from the pancreas. Despite their roles in maintaining glucose homeostasis, the distributions of insulin-responsive adrenergic and cholinergic neurons in the medulla are unknown. We fasted rats overnight and gave them insulin (10 U/kg i.p.) or saline after 2 weeks of handling. Blood samples were collected before injection and before perfusion at 90 min. We immunoperoxidase-stained transverse sections of perfused medulla to show Fos plus either phenylethanolamine N-methyltransferase (PNMT) or choline acetyltransferase (ChAT). Insulin injection lowered blood glucose from 4.9 ± 0.3 mmol/L to 1.7 ± 0.2 mmol/L (mean ± SEM; n = 6); saline injection had no effect. In insulin-treated rats, many PNMT-immunoreactive C1 neurons had Fos-immunoreactive nuclei, with the proportion of activated neurons being highest in the caudal part of the C1 column. In the rostral ventrolateral medulla, 33.3% ± 1.4% (n = 8) of C1 neurons were Fos-positive. Insulin also induced Fos in 47.2% ± 2.0% (n = 5) of dorsal medullary C3 neurons and in some C2 neurons. In the dorsal motor nucleus of the vagus (DMV), insulin evoked Fos in many ChAT-positive neurons. Activated neurons were concentrated in the medial and middle regions of the DMV beneath and just rostral to the area postrema. In control rats, very few C1, C2, or C3 neurons and no DMV neurons were Fos-positive. The high numbers of PNMT-immunoreactive and ChAT-immunoreactive neurons that express Fos after insulin treatment reinforce the importance of these neurons in the central response to a decrease in glucose bioavailability.
Collapse
Affiliation(s)
- M Senthilkumaran
- Cardiovascular Medicine, Human Physiology and Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, Australia.,School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - L Bobrovskaya
- School of Pharmacy and Medical Sciences, University of South Australia, Adelaide, South Australia, Australia
| | - A J M Verberne
- Clinical Pharmacology and Therapeutics Unit, Department of Medicine-Austin Health, University of Melbourne, Heidelberg, Victoria, Australia
| | - I J Llewellyn-Smith
- Cardiovascular Medicine, Human Physiology and Centre for Neuroscience, College of Medicine and Public Health, Flinders University, Bedford Park, South Australia, Australia
| |
Collapse
|
23
|
Korim WS, Elsaafien K, Basser JR, Setiadi A, May CN, Yao ST. In renovascular hypertension, TNF-α type-1 receptors in the area postrema mediate increases in cardiac and renal sympathetic nerve activity and blood pressure. Cardiovasc Res 2018; 115:1092-1101. [DOI: 10.1093/cvr/cvy268] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2018] [Revised: 10/02/2018] [Accepted: 10/24/2018] [Indexed: 12/16/2022] Open
Affiliation(s)
- Willian S Korim
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
- Wade Institute of Entrepreneurship, University of Melbourne, Parkville, VIC, Australia
| | - Khalid Elsaafien
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Jeremy R Basser
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Anthony Setiadi
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Clive N May
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - Song T Yao
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
- Florey Department of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| |
Collapse
|
24
|
Kakall ZM, Nedoboy PE, Farnham MMJ, Pilowsky PM. Activation of µ-opioid receptors in the rostral ventrolateral medulla blocks the sympathetic counterregulatory response to glucoprivation. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1115-R1122. [PMID: 30281326 DOI: 10.1152/ajpregu.00248.2018] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Activation of neurons in the rostral ventrolateral medulla (RVLM) following glucoprivation initiates sympathoadrenal activation, adrenaline release, and increased glucose production. Here, we aimed to determine the role of RVLM µ-opioid receptors in the counterregulatory response to systemic glucoprivation. Experiments were performed in pentobarbital sodium anesthetized male Sprague-Dawley rats ( n = 30). Bilateral activation of RVLM µ-opioid receptors with [d-Ala2, N-Me-Phe4, Gly5-ol]-enkephalin (DAMGO) (8 mM, 50 nl) depressed adrenal sympathetic nerve activity for ~60 min ( n = 6; Δ49.9 ± 5.8%, P < 0.05). The counterregulatory response to glucoprivation (measured by adrenal sympathetic efferent nerve activity) induced by 2-deoxyglucose (2-DG) ( n = 6; Δ63.6 ± 16.5%, P < 0.05) was completely blocked 60 min after DAMGO microinjections ( n = 6; Δ10.2 ± 3.5%, P < 0.05). Furthermore, DAMGO pretreatment attenuated the increase in blood glucose levels after 2-DG infusion ( n = 6; 6.1 ± 0.7mmol/l vs. baseline 5.2 ± 0.3mmol/l, P > 0.05) compared with 2-DG alone ( n = 6; 7.6 ± 0.4mmol/l vs. baseline 6.0 ± 0.4mmol/l, P < 0.05). Thus, activation of RVLM µ-opioid receptors attenuated the neural efferent response to glucoprivation and reduced glucose production.
Collapse
Affiliation(s)
- Zohra M Kakall
- Department of Physiology, Sydney Medical School, The University of Sydney , Sydney, NSW , Australia.,Heart Research Institute , Sydney, NSW , Australia
| | - Polina E Nedoboy
- Department of Physiology, Sydney Medical School, The University of Sydney , Sydney, NSW , Australia.,Heart Research Institute , Sydney, NSW , Australia
| | - Melissa M J Farnham
- Department of Physiology, Sydney Medical School, The University of Sydney , Sydney, NSW , Australia.,Heart Research Institute , Sydney, NSW , Australia
| | - Paul M Pilowsky
- Department of Physiology, Sydney Medical School, The University of Sydney , Sydney, NSW , Australia.,Heart Research Institute , Sydney, NSW , Australia
| |
Collapse
|
25
|
Bastianini S, Silvani A. Clinical implications of basic research. CLINICAL AND TRANSLATIONAL NEUROSCIENCE 2018. [DOI: 10.1177/2514183x18789327] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Affiliation(s)
- Stefano Bastianini
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| | - Alessandro Silvani
- Department of Biomedical and Neuromotor Sciences, University of Bologna, Bologna, Italy
| |
Collapse
|
26
|
Goforth PB, Myers MG. Roles for Orexin/Hypocretin in the Control of Energy Balance and Metabolism. Curr Top Behav Neurosci 2017; 33:137-156. [PMID: 27909992 DOI: 10.1007/7854_2016_51] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
The neuropeptide hypocretin is also commonly referred to as orexin, since its orexigenic action was recognized early. Orexin/hypocretin (OX) neurons project widely throughout the brain and the physiologic and behavioral functions of OX are much more complex than initially conceived based upon the stimulation of feeding. OX most notably controls functions relevant to attention, alertness, and motivation. OX also plays multiple crucial roles in the control of food intake, metabolism, and overall energy balance in mammals. OX signaling not only promotes food-seeking behavior upon short-term fasting to increase food intake and defend body weight, but, conversely, OX signaling also supports energy expenditure to protect against obesity. Furthermore, OX modulates the autonomic nervous system to control glucose metabolism, including during the response to hypoglycemia. Consistently, a variety of nutritional cues (including the hormones leptin and ghrelin) and metabolites (e.g., glucose, amino acids) control OX neurons. In this chapter, we review the control of OX neurons by nutritional/metabolic cues, along with our current understanding of the mechanisms by which OX and OX neurons contribute to the control of energy balance and metabolism.
Collapse
Affiliation(s)
- Paulette B Goforth
- Department of Pharmacology, University of Michigan, 1000 Wall St, 5131 Brehm Tower, Ann Arbor, MI, 48105, USA
| | - Martin G Myers
- Departments of Internal Medicine, and Molecular and Integrative Physiology, University of Michigan, 1000 Wall St, 6317 Brehm Tower, Ann Arbor, MI, 48105, USA.
| |
Collapse
|
27
|
Dempsey B, Le S, Turner A, Bokiniec P, Ramadas R, Bjaalie JG, Menuet C, Neve R, Allen AM, Goodchild AK, McMullan S. Mapping and Analysis of the Connectome of Sympathetic Premotor Neurons in the Rostral Ventrolateral Medulla of the Rat Using a Volumetric Brain Atlas. Front Neural Circuits 2017; 11:9. [PMID: 28298886 PMCID: PMC5331070 DOI: 10.3389/fncir.2017.00009] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 02/06/2017] [Indexed: 01/27/2023] Open
Abstract
Spinally projecting neurons in the rostral ventrolateral medulla (RVLM) play a critical role in the generation of vasomotor sympathetic tone and are thought to receive convergent input from neurons at every level of the neuraxis; the factors that determine their ongoing activity remain unresolved. In this study we use a genetically restricted viral tracing strategy to definitively map their spatially diffuse connectome. We infected bulbospinal RVLM neurons with a recombinant rabies variant that drives reporter expression in monosynaptically connected input neurons and mapped their distribution using an MRI-based volumetric atlas and a novel image alignment and visualization tool that efficiently translates the positions of neurons captured in conventional photomicrographs to Cartesian coordinates. We identified prominent inputs from well-established neurohumoral and viscero-sympathetic sensory actuators, medullary autonomic and respiratory subnuclei, and supramedullary autonomic nuclei. The majority of inputs lay within the brainstem (88–94%), and included putative respiratory neurons in the pre-Bötzinger Complex and post-inspiratory complex that are therefore likely to underlie respiratory-sympathetic coupling. We also discovered a substantial and previously unrecognized input from the region immediately ventral to nucleus prepositus hypoglossi. In contrast, RVLM sympathetic premotor neurons were only sparsely innervated by suprapontine structures including the paraventricular nucleus, lateral hypothalamus, periaqueductal gray, and superior colliculus, and we found almost no evidence of direct inputs from the cortex or amygdala. Our approach can be used to quantify, standardize and share complete neuroanatomical datasets, and therefore provides researchers with a platform for presentation, analysis and independent reanalysis of connectomic data.
Collapse
Affiliation(s)
- Bowen Dempsey
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Sheng Le
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Anita Turner
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Phil Bokiniec
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Radhika Ramadas
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Jan G Bjaalie
- Department of Anatomy, Institute of Basic Medical Sciences, University of Oslo Oslo, Norway
| | - Clement Menuet
- Department of Physiology, University of Melbourne Melbourne, VIC, Australia
| | - Rachael Neve
- Viral Core Facility, McGovern Institute for Brain Research, Massachusetts Institute of Technology Cambridge, MA, USA
| | - Andrew M Allen
- Department of Physiology, University of Melbourne Melbourne, VIC, Australia
| | - Ann K Goodchild
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| | - Simon McMullan
- Faculty of Medicine and Health Sciences, Neurobiology of Vital Systems, Macquarie University Sydney, NSW, Australia
| |
Collapse
|
28
|
Sabetghadam A, Korim WS, Verberne AJM. Perifornical hypothalamic pathway to the adrenal gland: Role for glutamatergic transmission in the glucose counter-regulatory response. Auton Neurosci 2017; 203:67-73. [PMID: 28173996 DOI: 10.1016/j.autneu.2017.02.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 01/31/2017] [Accepted: 02/01/2017] [Indexed: 01/06/2023]
Abstract
Adrenaline is an important counter-regulatory hormone that helps restore glucose homeostasis during hypoglycaemia. However, the neurocircuitry that connects the brain glucose sensors and the adrenal sympathetic outflow to the chromaffin cells is poorly understood. We used electrical microstimulation of the perifornical hypothalamus (PeH) and the rostral ventrolateral medulla (RVLM) combined with adrenal sympathetic nerve activity (ASNA) recording to examine the relationship between the RVLM, the PeH and ASNA. In urethane-anaesthetised male Sprague-Dawley rats, intermittent single pulse electrical stimulation of the rostroventrolateral medulla (RVLM) elicited an evoked ASNA response that consisted of early (60±3ms) and late peaks (135±4ms) of preganglionic and postganglionic activity. In contrast, RVLM stimulation evoked responses in lumbar sympathetic nerve activity that were almost entirely postganglionic. PeH stimulation also produced an evoked excitatory response consisting of both preganglionic and postganglionic excitatory peaks in ASNA. Both peaks in ASNA following RVLM stimulation were reduced by intrathecal kynurenic acid (KYN) injection. In addition, the ASNA response to systemic neuroglucoprivation induced by 2-deoxy-d-glucose was abolished by bilateral microinjection of KYN into the RVLM. This suggests that a glutamatergic pathway from the perifornical hypothalamus (PeH) relays in the RVLM to activate the adrenal SPN and so modulate ASNA. The main findings of this study are that (i) adrenal premotor neurons in the RVLM may be, at least in part, glutamatergic and (ii) that the input to these neurons that is activated during neuroglucoprivation is also glutamatergic.
Collapse
Affiliation(s)
- A Sabetghadam
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - W S Korim
- Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, Victoria, Australia
| | - A J M Verberne
- University of Melbourne, Clinical Pharmacology and Therapeutics Unit, Department of Medicine, Austin Health, Heidelberg, Victoria 3084, Australia.
| |
Collapse
|
29
|
Verberne AJM, Korim WS, Sabetghadam A, Llewellyn-Smith IJ. Adrenaline: insights into its metabolic roles in hypoglycaemia and diabetes. Br J Pharmacol 2016; 173:1425-37. [PMID: 26896587 DOI: 10.1111/bph.13458] [Citation(s) in RCA: 49] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Revised: 01/20/2016] [Accepted: 02/11/2016] [Indexed: 01/05/2023] Open
Abstract
Adrenaline is a hormone that has profound actions on the cardiovascular system and is also a mediator of the fight-or-flight response. Adrenaline is now increasingly recognized as an important metabolic hormone that helps mobilize energy stores in the form of glucose and free fatty acids in preparation for physical activity or for recovery from hypoglycaemia. Recovery from hypoglycaemia is termed counter-regulation and involves the suppression of endogenous insulin secretion, activation of glucagon secretion from pancreatic α-cells and activation of adrenaline secretion. Secretion of adrenaline is controlled by presympathetic neurons in the rostroventrolateral medulla, which are, in turn, under the control of central and/or peripheral glucose-sensing neurons. Adrenaline is particularly important for counter-regulation in individuals with type 1 (insulin-dependent) diabetes because these patients do not produce endogenous insulin and also lose their ability to secrete glucagon soon after diagnosis. Type 1 diabetic patients are therefore critically dependent on adrenaline for restoration of normoglycaemia and attenuation or loss of this response in the hypoglycaemia unawareness condition can have serious, sometimes fatal, consequences. Understanding the neural control of hypoglycaemia-induced adrenaline secretion is likely to identify new therapeutic targets for treating this potentially life-threatening condition.
Collapse
Affiliation(s)
- A J M Verberne
- Clinical Pharmacology and Therapeutics Unit, Department of Medicine, Austin Health, University of Melbourne, Heidelberg, VIC, Australia
| | - W S Korim
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - A Sabetghadam
- The Florey Institute of Neuroscience and Mental Health, University of Melbourne, Parkville, VIC, Australia
| | - I J Llewellyn-Smith
- Cardiovascular Medicine and Human Physiology, Flinders University, Bedford Park, SA, Australia
| |
Collapse
|
30
|
Korim WS, Llewellyn-Smith IJ, Verberne AJM. Activation of Medulla-Projecting Perifornical Neurons Modulates the Adrenal Sympathetic Response to Hypoglycemia: Involvement of Orexin Type 2 (OX2-R) Receptors. Endocrinology 2016; 157:810-9. [PMID: 26653571 DOI: 10.1210/en.2015-1712] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Iatrogenic hypoglycemia in response to insulin treatment is commonly experienced by patients with type 1 diabetes and can be life threatening. The body releases epinephrine in an attempt to counterregulate hypoglycemia, but the neural mechanisms underlying this phenomenon remain to be elucidated. Orexin neurons in the perifornical hypothalamus (PeH) project to the rostral ventrolateral medulla (RVLM) and are likely to be involved in epinephrine secretion during hypoglycemia. In anesthetized rats, we report that hypoglycemia increases the sympathetic preganglionic discharge to the adrenal gland by activating PeH orexin neurons that project to the RVLM (PeH-RVLM). Electrophysiological characterization shows that the majority of identified PeH-RVLM neurons, including a subpopulation of orexin neurons, are activated in response to hypoglycemia or glucoprivation. Furthermore, the excitatory input from the PeH is mediated by orexin type 2 receptors in the RVLM. These results suggest that activation of orexin PeH-RVLM neurons and orexin type 2 receptors in the RVLM facilitates epinephrine release by increasing sympathetic drive to adrenal chromaffin cells during hypoglycemia.
Collapse
Affiliation(s)
- Willian S Korim
- Clinical Pharmacology and Therapeutics Unit (W.S.K., A.J.M.V.), Department of Medicine Austin Health, University of Melbourne, Heidelberg, Victoria 3084, Australia; Florey Institute of Neuroscience and Mental Health (W.S.K.), University of Melbourne, Parkville, Victoria 3052, Australia; and Cardiovascular Medicine (I.J.L.-S.), Human Physiology and Centre for Neuroscience, School of Medicine, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Ida J Llewellyn-Smith
- Clinical Pharmacology and Therapeutics Unit (W.S.K., A.J.M.V.), Department of Medicine Austin Health, University of Melbourne, Heidelberg, Victoria 3084, Australia; Florey Institute of Neuroscience and Mental Health (W.S.K.), University of Melbourne, Parkville, Victoria 3052, Australia; and Cardiovascular Medicine (I.J.L.-S.), Human Physiology and Centre for Neuroscience, School of Medicine, Flinders University, Bedford Park, South Australia 5042, Australia
| | - Anthony J M Verberne
- Clinical Pharmacology and Therapeutics Unit (W.S.K., A.J.M.V.), Department of Medicine Austin Health, University of Melbourne, Heidelberg, Victoria 3084, Australia; Florey Institute of Neuroscience and Mental Health (W.S.K.), University of Melbourne, Parkville, Victoria 3052, Australia; and Cardiovascular Medicine (I.J.L.-S.), Human Physiology and Centre for Neuroscience, School of Medicine, Flinders University, Bedford Park, South Australia 5042, Australia
| |
Collapse
|
31
|
Tsuneki H, Nagata T, Fujita M, Kon K, Wu N, Takatsuki M, Yamaguchi K, Wada T, Nishijo H, Yanagisawa M, Sakurai T, Sasaoka T. Nighttime Administration of Nicotine Improves Hepatic Glucose Metabolism via the Hypothalamic Orexin System in Mice. Endocrinology 2016; 157:195-206. [PMID: 26492471 DOI: 10.1210/en.2015-1488] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Nicotine is known to affect the metabolism of glucose; however, the underlying mechanism remains unclear. Therefore, we here investigated whether nicotine promoted the central regulation of glucose metabolism, which is closely linked to the circadian system. The oral intake of nicotine in drinking water, which mainly occurred during the nighttime active period, enhanced daily hypothalamic prepro-orexin gene expression and reduced hyperglycemia in type 2 diabetic db/db mice without affecting body weight, body fat content, and serum levels of insulin. Nicotine administered at the active period appears to be responsible for the effect on blood glucose, because nighttime but not daytime injections of nicotine lowered blood glucose levels in db/db mice. The chronic oral treatment with nicotine suppressed the mRNA levels of glucose-6-phosphatase, the rate-limiting enzyme of gluconeogenesis, in the liver of db/db and wild-type control mice. In the pyruvate tolerance test to evaluate hepatic gluconeogenic activity, the oral nicotine treatment moderately suppressed glucose elevations in normal mice and mice lacking dopamine receptors, whereas this effect was abolished in orexin-deficient mice and hepatic parasympathectomized mice. Under high-fat diet conditions, the oral intake of nicotine lowered blood glucose levels at the daytime resting period in wild-type, but not orexin-deficient, mice. These results indicated that the chronic daily administration of nicotine suppressed hepatic gluconeogenesis via the hypothalamic orexin-parasympathetic nervous system. Thus, the results of the present study may provide an insight into novel chronotherapy for type 2 diabetes that targets the central cholinergic and orexinergic systems.
Collapse
MESH Headings
- Animals
- Crosses, Genetic
- Diabetes Mellitus, Type 2/blood
- Diabetes Mellitus, Type 2/complications
- Diabetes Mellitus, Type 2/drug therapy
- Diabetes Mellitus, Type 2/metabolism
- Diet, High-Fat/adverse effects
- Drug Chronotherapy
- Gene Expression Regulation/drug effects
- Gluconeogenesis/drug effects
- Hyperglycemia/prevention & control
- Hypoglycemic Agents/administration & dosage
- Hypoglycemic Agents/therapeutic use
- Hypothalamus/drug effects
- Hypothalamus/metabolism
- Insulin Resistance
- Liver/drug effects
- Liver/metabolism
- Male
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Mutant Strains
- Nicotine/administration & dosage
- Nicotine/therapeutic use
- Nicotinic Agonists/administration & dosage
- Nicotinic Agonists/therapeutic use
- Obesity/complications
- Obesity/etiology
- Orexins/agonists
- Orexins/genetics
- Orexins/metabolism
- Receptors, Dopamine D1/genetics
- Receptors, Dopamine D1/metabolism
- Receptors, Dopamine D2/genetics
- Receptors, Dopamine D2/metabolism
Collapse
Affiliation(s)
- Hiroshi Tsuneki
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Takashi Nagata
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Mikio Fujita
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Kanta Kon
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Naizhen Wu
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Mayumi Takatsuki
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Kaoru Yamaguchi
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Tsutomu Wada
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Hisao Nishijo
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Masashi Yanagisawa
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Takeshi Sakurai
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| | - Toshiyasu Sasaoka
- Department of Clinical Pharmacology (H.T., T.N., M.F., K.K., N.W., M.T., K.Y., T.W., T.Sas.) and System Emotional Science (H.N.), University of Toyama, Toyama 930-0194, Japan; International Institute for Integrative Sleep Medicine (WPI-IIIS) (M.Y.), University of Tsukuba, Tsukuba 305-8575, Japan; Department of Molecular Genetics (M.Y.), University of Texas Southwestern Medical Center, Dallas, Texas 75390; and Department of Molecular Neuroscience and Integrative Physiology (T.Sak.), Faculty of Medicine, Kanazawa University, Kanazawa, Ishikawa 920-8640, Japan
| |
Collapse
|
32
|
Otlivanchik O, Sanders NM, Dunn-Meynell A, Levin BE. Orexin signaling is necessary for hypoglycemia-induced prevention of conditioned place preference. Am J Physiol Regul Integr Comp Physiol 2015; 310:R66-73. [PMID: 26511522 DOI: 10.1152/ajpregu.00066.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 10/19/2015] [Indexed: 01/24/2023]
Abstract
While the neural control of glucoregulatory responses to insulin-induced hypoglycemia is beginning to be elucidated, brain sites responsible for behavioral responses to hypoglycemia are relatively poorly understood. To help elucidate central control mechanisms associated with hypoglycemia unawareness, we first evaluated the effect of recurrent hypoglycemia on a simple behavioral measure, the robust feeding response to hypoglycemia, in rats. First, food intake was significantly, and similarly, increased above baseline saline-induced intake (1.1 ± 0.2 g; n = 8) in rats experiencing a first (4.4 ± 0.3; n = 8) or third daily episode of recurrent insulin-induced hypoglycemia (IIH, 3.7 ± 0.3 g; n = 9; P < 0.05). Because food intake was not impaired as a result of prior IIH, we next developed an alternative animal model of hypoglycemia-induced behavioral arousal using a conditioned place preference (CPP) model. We found that hypoglycemia severely blunted previously acquired CPP in rats and that recurrent hypoglycemia prevented this blunting. Pretreatment with a brain penetrant, selective orexin receptor-1 antagonist, SB-334867A, blocked hypoglycemia-induced blunting of CPP. Recurrently hypoglycemic rats also showed decreased preproorexin expression in the perifornical hypothalamus (50%) but not in the adjacent lateral hypothalamus. Pretreatment with sertraline, previously shown to prevent hypoglycemia-associated glucoregulatory failure, did not prevent blunting of hypoglycemia-induced CPP prevention by recurrent hypoglycemia. This work describes the first behavioral model of hypoglycemia unawareness and suggests a role for orexin neurons in mediating behavioral responses to hypoglycemia.
Collapse
Affiliation(s)
- Oleg Otlivanchik
- Graduate School of Biomedical Sciences, Rutgers University, Newark, New Jersey; Department of Neurology, New Jersey Medical School, Rutgers University, Newark, New Jersey
| | | | - Ambrose Dunn-Meynell
- Graduate School of Biomedical Sciences, Rutgers University, Newark, New Jersey; Department of Neurology, New Jersey Medical School, Rutgers University, Newark, New Jersey; Neurology Service, Veterans Affairs Medical Center, East Orange, New Jersey; and
| | - Barry E Levin
- Department of Neurology, New Jersey Medical School, Rutgers University, Newark, New Jersey; Neurology Service, Veterans Affairs Medical Center, East Orange, New Jersey; and
| |
Collapse
|
33
|
Li AJ, Wang Q, Elsarelli MM, Brown RL, Ritter S. Hindbrain Catecholamine Neurons Activate Orexin Neurons During Systemic Glucoprivation in Male Rats. Endocrinology 2015; 156:2807-20. [PMID: 25978516 PMCID: PMC5393341 DOI: 10.1210/en.2015-1138] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Hindbrain catecholamine neurons are required for elicitation of feeding responses to glucose deficit, but the forebrain circuitry required for these responses is incompletely understood. Here we examined interactions of catecholamine and orexin neurons in eliciting glucoprivic feeding. Orexin neurons, located in the perifornical lateral hypothalamus (PeFLH), are heavily innervated by hindbrain catecholamine neurons, stimulate food intake, and increase arousal and behavioral activation. Orexin neurons may therefore contribute importantly to appetitive responses, such as food seeking, during glucoprivation. Retrograde tracing results showed that nearly all innervation of the PeFLH from the hindbrain originated from catecholamine neurons and some raphe nuclei. Results also suggested that many catecholamine neurons project collaterally to the PeFLH and paraventricular hypothalamic nucleus. Systemic administration of the antiglycolytic agent, 2-deoxy-D-glucose, increased food intake and c-Fos expression in orexin neurons. Both responses were eliminated by a lesion of catecholamine neurons innervating orexin neurons using the retrogradely transported immunotoxin, anti-dopamine-β-hydroxylase saporin, which is specifically internalized by dopamine-β-hydroxylase-expressing catecholamine neurons. Using designer receptors exclusively activated by designer drugs in transgenic rats expressing Cre recombinase under the control of tyrosine hydroxylase promoter, catecholamine neurons in cell groups A1 and C1 of the ventrolateral medulla were activated selectively by peripheral injection of clozapine-N-oxide. Clozapine-N-oxide injection increased food intake and c-Fos expression in PeFLH orexin neurons as well as in paraventricular hypothalamic nucleus neurons. In summary, catecholamine neurons are required for the activation of orexin neurons during glucoprivation. Activation of orexin neurons may contribute to appetitive responses required for glucoprivic feeding.
Collapse
Affiliation(s)
- Ai-Jun Li
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Qing Wang
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Megan M Elsarelli
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - R Lane Brown
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| | - Sue Ritter
- Programs in Neuroscience, Washington State University, Pullman, Washington 99164-7620
| |
Collapse
|
34
|
Bou Farah L, Bowman BR, Bokiniec P, Karim S, Le S, Goodchild AK, McMullan S. Somatostatin in the rat rostral ventrolateral medulla: Origins and mechanism of action. J Comp Neurol 2015; 524:323-42. [PMID: 26131686 DOI: 10.1002/cne.23846] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2015] [Revised: 06/22/2015] [Accepted: 06/23/2015] [Indexed: 01/24/2023]
Abstract
Somatostatin (SST) or agonists of the SST-2 receptor (sst2 ) in the rostral ventrolateral medulla (RVLM) lower sympathetic nerve activity, arterial pressure, and heart rate, or when administered within the Bötzinger region, evoke apneusis. Our aims were to describe the mechanisms responsible for the sympathoinhibitory effects of SST on bulbospinal neurons and to identify likely sources of RVLM SST release. Patch clamp recordings were made from bulbospinal RVLM neurons (n = 31) in brainstem slices prepared from juvenile rat pups. Overall, 58% of neurons responded to SST, displaying an increase in conductance that reversed at -93 mV, indicative of an inwardly rectifying potassium channel (GIRK) mechanism. Blockade of sst2 abolished this effect, but application of tetrodotoxin did not, indicating that the SST effect is independent of presynaptic activity. Fourteen bulbospinal RVLM neurons were recovered for immunohistochemistry; nine were SST-insensitive and did not express sst2a . Three out of five responsive neurons were sst2a -immunoreactive. Neurons that contained preprosomatostatin mRNA and cholera-toxin-B retrogradely transported from the RVLM were detected in: paratrigeminal nucleus, lateral parabrachial nucleus, Kölliker-Fuse nucleus, ventrolateral periaqueductal gray area, central nucleus of the amygdala, sublenticular extended amygdala, interstitial nucleus of the posterior limb of the anterior commissure nucleus, and bed nucleus of the stria terminalis. Thus, those brain regions are putative sources of endogenous SST release that, when activated, may evoke sympathoinhibitory effects via interactions with subsets of sympathetic premotor neurons that express sst2 .
Collapse
Affiliation(s)
- Lama Bou Farah
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Belinda R Bowman
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Phil Bokiniec
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Shafinaz Karim
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Sheng Le
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Ann K Goodchild
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| | - Simon McMullan
- Australian School of Advanced Medicine, Macquarie University, 2109, NSW, Australia
| |
Collapse
|
35
|
Otlivanchik O, Le Foll C, Levin BE. Perifornical hypothalamic orexin and serotonin modulate the counterregulatory response to hypoglycemic and glucoprivic stimuli. Diabetes 2015; 64:226-35. [PMID: 25114294 PMCID: PMC4274798 DOI: 10.2337/db14-0671] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Previous reports suggested an important role for serotonin (5-hydroxytryptamine [5-HT]) in enhancing the counterregulatory response (CRR) to hypoglycemia. To elucidate the sites of action mediating this effect, we initially found that insulin-induced hypoglycemia stimulates 5-HT release in widespread forebrain regions, including the perifornical hypothalamus (PFH; 30%), ventromedial hypothalamus (34%), paraventricular hypothalamus (34%), paraventricular thalamic nucleus (64%), and cerebral cortex (63%). Of these, we focused on the PFH because of its known modulation of diverse neurohumoral and behavioral responses. In awake, behaving rats, bilateral PFH glucoprivation with 5-thioglucose stimulated adrenal medullary epinephrine (Epi) release (3,153%) and feeding (400%), while clamping PFH glucose at postprandial brain levels blunted the Epi response to hypoglycemia by 30%. The PFH contained both glucose-excited (GE) and glucose-inhibited (GI) neurons; GE neurons were primarily excited, while GI neurons were equally excited or inhibited by 5-HT at hypoglycemic glucose levels in vitro. Also, 5-HT stimulated lactate production by cultured hypothalamic astrocytes. Depleting PFH 5-HT blunted the Epi (but not feeding) response to focal PFH (69%) and systemic glucoprivation (39%), while increasing PFH 5-HT levels amplified the Epi response to hypoglycemia by 32%. Finally, the orexin 1 receptor antagonist SB334867A attenuated both the Epi (65%) and feeding (47%) responses to focal PFH glucoprivation. Thus we have identified the PFH as a glucoregulatory region where both 5-HT and orexin modulate the CRR and feeding responses to glucoprivation.
Collapse
Affiliation(s)
- Oleg Otlivanchik
- Graduate School of Biomedical Sciences, Rutgers, Newark, NJ Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers, Newark, NJ
| | - Christelle Le Foll
- Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers, Newark, NJ
| | - Barry E Levin
- Department of Neurology and Neurosciences, New Jersey Medical School, Rutgers, Newark, NJ Neurology Service, Veterans Affairs Medical Center, East Orange, NJ
| |
Collapse
|
36
|
Bochorishvili G, Nguyen T, Coates MB, Viar KE, Stornetta RL, Guyenet PG. The orexinergic neurons receive synaptic input from C1 cells in rats. J Comp Neurol 2014; 522:3834-46. [PMID: 24984694 DOI: 10.1002/cne.23643] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2014] [Revised: 06/25/2014] [Accepted: 06/27/2014] [Indexed: 11/10/2022]
Abstract
The C1 cells, located in the rostral ventrolateral medulla (RVLM), are activated by pain, hypoxia, hypoglycemia, infection, and hypotension and elicit cardiorespiratory stimulation, adrenaline and adrenocorticotropic hormone (ACTH) release, and arousal. The orexin neurons contribute to the autonomic responses to acute psychological stress. Here, using an anatomical approach, we consider whether the orexin neurons could also be contributing to the autonomic effects elicited by C1 neuron activation. Phenylethanolamine N-methyl transferase-immunoreactive (PNMT-ir) axons were detected among orexin-ir somata, and close appositions between PNMT-ir axonal varicosities and orexin-ir profiles were observed. The existence of synapses between PNMT-ir boutons labeled with diaminobenzidine and orexinergic neurons labeled with immunogold was confirmed by electron microscopy. We labeled RVLM neurons with a lentiviral vector that expresses the fusion protein ChR2-mCherry under the control of the catecholaminergic neuron-selective promoter PRSx8 and obtained light and ultrastructural evidence that these neurons innervate the orexin cells. By using a Cre-dependent adeno-associated vector and TH-Cre rats, we confirmed that the projection from RVLM catecholaminergic neurons to the orexinergic neurons originates predominantly from PNMT-ir catecholaminergic (i.e., C1 cells). The C1 neurons were found to establish predominantly asymmetric synapses with orexin-ir cell bodies or dendrites. These synapses were packed with small clear vesicles and also contained dense-core vesicles. In summary, the orexin neurons are among the hypothalamic neurons contacted and presumably excited by the C1 cells. The C1-orexin neuronal connection is probably one of several suprabulbar pathways through which the C1 neurons activate breathing and the circulation, raise blood glucose, and facilitate arousal from sleep.
Collapse
|