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Worth AA, Feetham CH, Morrissey NA, Luckman SM. Paraventricular oxytocin neurons impact energy intake and expenditure: projections to the bed nucleus of the stria terminalis reduce sucrose consumption. Front Endocrinol (Lausanne) 2024; 15:1449326. [PMID: 39286269 PMCID: PMC11402739 DOI: 10.3389/fendo.2024.1449326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Accepted: 08/12/2024] [Indexed: 09/19/2024] Open
Abstract
Background The part played by oxytocin and oxytocin neurons in the regulation of food intake is controversial. There is much pharmacological data to support a role for oxytocin notably in regulating sugar consumption, however, several recent experiments have questioned the importance of oxytocin neurons themselves. Methods Here we use a combination of histological and chemogenetic techniques to investigate the selective activation or inhibition of oxytocin neurons in the hypothalamic paraventricular nucleus (OxtPVH). We then identify a pathway from OxtPVH neurons to the bed nucleus of the stria terminalis using the cell-selective expression of channel rhodopsin. Results OxtPVH neurons increase their expression of cFos after both physiological (fast-induced re-feeding or oral lipid) and pharmacological (systemic administration of cholecystokinin or lithium chloride) anorectic signals. Chemogenetic activation of OxtPVH neurons is sufficient to decrease free-feeding in Oxt Cre:hM3Dq mice, while inhibition in Oxt Cre:hM4Di mice attenuates the response to administration of cholecystokinin. Activation of OxtPVH neurons also increases energy expenditure and core-body temperature, without a significant effect on locomotor activity. Finally, the selective, optogenetic stimulation of a pathway from OxtPVH neurons to the bed nucleus of the stria terminalis reduces the consumption of sucrose. Conclusion Our results support a role for oxytocin neurons in the regulation of whole-body metabolism, including a modulatory action on food intake and energy expenditure. Furthermore, we demonstrate that the pathway from OxtPVH neurons to the bed nucleus of the stria terminalis can regulate sugar consumption.
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Affiliation(s)
- Amy A Worth
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Claire H Feetham
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Nicole A Morrissey
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
| | - Simon M Luckman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, United Kingdom
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2
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Gruber T, Lechner F, Krieger JP, García-Cáceres C. Neuroendocrine gut-brain signaling in obesity. Trends Endocrinol Metab 2024:S1043-2760(24)00120-6. [PMID: 38821753 DOI: 10.1016/j.tem.2024.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2024] [Revised: 04/29/2024] [Accepted: 05/03/2024] [Indexed: 06/02/2024]
Abstract
The past decades have witnessed the rise and fall of several, largely unsuccessful, therapeutic attempts to bring the escalating obesity pandemic to a halt. Looking back to look ahead, the field has now put its highest hopes in translating insights from how the gastrointestinal (GI) tract communicates with the brain to calibrate behavior, physiology, and metabolism. A major focus of this review is to summarize the latest advances in comprehending the neuroendocrine aspects of this so-called 'gut-brain axis' and to explore novel concepts, cutting-edge technologies, and recent paradigm-shifting experiments. These exciting insights continue to refine our understanding of gut-brain crosstalk and are poised to promote the development of additional therapeutic avenues at the dawn of a new era of antiobesity therapeutics.
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Affiliation(s)
- Tim Gruber
- Department of Metabolism and Nutritional Programming, Van Andel Institute, Grand Rapids, MI 49506, USA; Department of Epigenetics, Van Andel Institute, Grand Rapids, MI 49506, USA; German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany.
| | - Franziska Lechner
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany
| | - Jean-Philippe Krieger
- Institute of Veterinary Pharmacology and Toxicology, University of Zurich-Vetsuisse, 8057 Zurich, Switzerland; Institute of Neuroscience and Physiology, University of Gothenburg, 40530 Gothenburg, Sweden
| | - Cristina García-Cáceres
- German Center for Diabetes Research (DZD), 85764 Neuherberg, Germany; Institute for Diabetes and Obesity, Helmholtz Diabetes Center, Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), 85764 Neuherberg, Germany; Medizinische Klinik und Poliklinik IV, Klinikum der Universität, Ludwig-Maximilians-Universität München, 80336 Munich, Germany.
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Tsai SF, Kuo YM. The Role of Central Oxytocin in Autonomic Regulation. CHINESE J PHYSIOL 2024; 67:3-14. [PMID: 38780268 DOI: 10.4103/ejpi.ejpi-d-23-00037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Accepted: 11/10/2023] [Indexed: 05/25/2024] Open
Abstract
Oxytocin (OXT), a neuropeptide originating from the hypothalamus and traditionally associated with peripheral functions in parturition and lactation, has emerged as a pivotal player in the central regulation of the autonomic nervous system (ANS). This comprehensive ANS, comprising sympathetic, parasympathetic, and enteric components, intricately combines sympathetic and parasympathetic influences to provide unified control. The central oversight of sympathetic and parasympathetic outputs involves a network of interconnected regions spanning the neuroaxis, playing a pivotal role in the real-time regulation of visceral function, homeostasis, and adaptation to challenges. This review unveils the significant involvement of the central OXT system in modulating autonomic functions, shedding light on diverse subpopulations of OXT neurons within the paraventricular nucleus of the hypothalamus and their intricate projections. The narrative progresses from the basics of central ANS regulation to a detailed discussion of the central controls of sympathetic and parasympathetic outflows. The subsequent segment focuses specifically on the central OXT system, providing a foundation for exploring the central role of OXT in ANS regulation. This review synthesizes current knowledge, paving the way for future research endeavors to unravel the full scope of autonomic control and understand multifaceted impact of OXT on physiological outcomes.
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Affiliation(s)
- Sheng-Feng Tsai
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yu-Min Kuo
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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4
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Sun HZ, Li CY, Shi Y, Li JJ, Wang YY, Han LN, Zhu LJ, Zhang YF. Effect of exogenous hydrogen sulfide in the nucleus tractus solitarius on gastric motility in rats. World J Gastroenterol 2023; 29:4557-4570. [PMID: 37621756 PMCID: PMC10445002 DOI: 10.3748/wjg.v29.i29.4557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 06/29/2023] [Accepted: 07/19/2023] [Indexed: 08/02/2023] Open
Abstract
BACKGROUND Hydrogen sulfide (H2S) is a recently discovered gaseous neurotransmitter in the nervous and gastrointestinal systems. It exerts its effects through multiple signaling pathways, impacting various physiological activities. The nucleus tractus solitarius (NTS), a vital nucleus involved in visceral sensation, was investigated in this study to understand the role of H2S in regulating gastric function in rats. AIM To examine whether H2S affects the nuclear factor kappa-B (NF-κB) and transient receptor potential vanilloid 1 pathways and the neurokinin 1 (NK1) receptor in the NTS. METHODS Immunohistochemical and fluorescent double-labeling techniques were employed to identify cystathionine beta-synthase (CBS) and c-Fos co-expressed positive neurons in the NTS during rat stress. Gastric motility curves were recorded by inserting a pressure-sensing balloon into the pylorus through the stomach fundus. Changes in gastric motility were observed before and after injecting different doses of NaHS (4 nmol and 8 nmol), physiological saline, Capsazepine (4 nmol) + NaHS (4 nmol), pyrrolidine dithiocarbamate (PDTC, 4 nmol) + NaHS (4 nmol), and L703606 (4 nmol) + NaHS (4 nmol). RESULTS We identified a significant increase in the co-expression of c-Fos and CBS positive neurons in the NTS after 1 h and 3 h of restraint water-immersion stress compared to the expressions observed in the control group. Intra-NTS injection of NaHS at different doses significantly inhibited gastric motility in rats (P < 0.01). However, injection of saline, first injection NF-κB inhibitor PDTC or transient receptor potential vanilloid 1 (TRPV1) antagonist Capsazepine or NK1 receptor blockers L703606 and then injection NaHS did not produce significant changes (P > 0.05). CONCLUSION NTS contains neurons co-expressing CBS and c-Fos, and the injection of NaHS into the NTS can suppress gastric motility in rats. This effect may be mediated by activating TRPV1 and NK1 receptors via the NF-κB channel.
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Affiliation(s)
- Hong-Zhao Sun
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
| | - Chen-Yu Li
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
| | - Yuan Shi
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
| | - Jin-Jin Li
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
| | - Yi-Ya Wang
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
| | - Li-Na Han
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
| | - Lu-Jie Zhu
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
| | - Ya-Fei Zhang
- College of Life Science, Qi Lu Normal University, Zhangqiu 250200, Shandong Province, China
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5
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Carson KE, Alvarez J, Mackley J, Travagli RA, Browning KN. Perinatal high-fat diet exposure alters oxytocin and corticotropin releasing factor inputs onto vagal neurocircuits controlling gastric motility. J Physiol 2023; 601:2853-2875. [PMID: 37154244 PMCID: PMC10524104 DOI: 10.1113/jp284726] [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: 03/20/2023] [Accepted: 05/03/2023] [Indexed: 05/10/2023] Open
Abstract
Perinatal high-fat diet (pHFD) exposure alters the development of vagal neurocircuits that control gastrointestinal (GI) motility and reduce stress resiliency in offspring. Descending oxytocin (OXT; prototypical anti-stress peptide) and corticotropin releasing factor (CRF; prototypical stress peptide) inputs from the paraventricular nucleus (PVN) of the hypothalamus to the dorsal motor nucleus of the vagus (DMV) modulate the GI stress response. How these descending inputs, and their associated changes to GI motility and stress responses, are altered following pHFD exposure are, however, unknown. The present study used retrograde neuronal tracing experiments, cerebrospinal fluid extraction, in vivo recordings of gastric tone, motility and gastric emptying rates, and in vitro electrophysiological recordings from brainstem slice preparations to investigate the hypothesis that pHFD alters descending PVN-DMV inputs and dysregulates vagal brain-gut responses to stress. Compared to controls, rats exposed to pHFD had slower gastric emptying rates and did not respond to acute stress with the expected delay in gastric emptying. Neuronal tracing experiments demonstrated that pHFD reduced the number of PVNOXT neurons that project to the DMV, but increased PVNCRF neurons. Both in vitro electrophysiology recordings of DMV neurons and in vivo recordings of gastric motility and tone demonstrated that, following pHFD, PVNCRF -DMV projections were tonically active, and that pharmacological antagonism of brainstem CRF1 receptors restored the appropriate gastric response to brainstem OXT application. These results suggest that pHFD exposure disrupts descending PVN-DMV inputs, leading to a dysregulated vagal brain-gut response to stress. KEY POINTS: Maternal high-fat diet exposure is associated with gastric dysregulation and stress sensitivity in offspring. The present study demonstrates that perinatal high-fat diet exposure downregulates hypothalamic-vagal oxytocin (OXT) inputs but upregulates hypothalamic-vagal corticotropin releasing factor (CRF) inputs. Both in vitro and in vivo studies demonstrated that, following perinatal high-fat diet, CRF receptors were tonically active at NTS-DMV synapses, and that pharmacological antagonism of these receptors restored the appropriate gastric response to OXT. The current study suggests that perinatal high-fat diet exposure disrupts descending PVN-DMV inputs, leading to a dysregulated vagal brain-gut response to stress.
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Affiliation(s)
- Kaitlin E. Carson
- Department of Neural and Behavioral Sciences, Pennsylvania State College of Medicine, Hershey, PA
| | - Jared Alvarez
- Barrett Honors College, Arizona State University, Tempe, AZ
| | - Jasmine Mackley
- Schreyer Honors College, Pennsylvania State University, State College, PA
| | | | - Kirsteen N. Browning
- Address for correspondence: Kirsteen N. Browning, PhD, Penn State College of Medicine, 500 University Drive, MC H109, Hershey, PA, 17033;
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6
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Kobashi M, Shimatani Y, Fujita M. Oxytocin increased intragastric pressure in the forestomach of rats via the dorsal vagal complex. Physiol Behav 2023; 261:114087. [PMID: 36646162 DOI: 10.1016/j.physbeh.2023.114087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 01/11/2023] [Accepted: 01/12/2023] [Indexed: 01/15/2023]
Abstract
We previously reported that appetite-enhancing peptides facilitated phasic contractions of the distal stomach and relaxed the forestomach via the dorsal vagal complex (DVC). The present study investigated the effects of anorectic substances on gastric reservoir function. The effects of oxytocin on the motility of the forestomach were examined in rats anesthetized with urethane-chloralose. Gastric motor responses were measured using an intragastric balloon. The fourth ventricular administration of oxytocin (0.1 - 1.0 nmol) increased intragastric pressure (IGP) in the forestomach in a dose-dependent manner. Conversely, the administration of oxytocin (0.3 nmol) suppressed phasic contractions of the distal stomach. These responses were opposite to those of appetite-enhancing peptides in previous studies. The oxytocin response in the forestomach was not observed after bilateral cervical vagotomy. The effects of oxytocin on forestomach motility were examined in animals that underwent ablation of the area postrema (AP) to clarify its involvement. Although the magnitude of the response to the fourth ventricular administration of oxytocin decreased, a significant response was still observed. A microinjection of oxytocin (3 pmol) into the AP, the left medial nucleus of the nucleus tractus solitarius (mNTS), the left commissural part of the NTS, or the left dorsal motor nucleus of the vagus was performed. The oxytocin injection into the AP and/or mNTS induced a rapid and large increase in IGP in the forestomach. Prior injection of L-368,899, an oxytocin receptor antagonist, into both the AP and mNTS attenuated the oxytocin response of the forestomach induced by fourth ventricular administration of oxytocin. These results indicate that oxytocin acts on the AP and/or mNTS to increase IGP in the forestomach via vagal preganglionic neurons.
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Affiliation(s)
- Motoi Kobashi
- Department of Oral Physiology, Faculty of Medicine, Dentistry and Pharmaceutical Science, Okayama University, Okayama, 700-8525, Japan.
| | - Yuichi Shimatani
- Department of Medical Engineering, Faculty of Engineering, Tokyo City University, Tokyo, 158-8557, Japan
| | - Masako Fujita
- Department of Oral Physiology, Faculty of Medicine, Dentistry and Pharmaceutical Science, Okayama University, Okayama, 700-8525, Japan
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7
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Jiang Y, Zimmerman JE, Browning KN, Travagli RA. Stress-induced neuroplasticity in the gastric response to brainstem oxytocin in male rats. Am J Physiol Gastrointest Liver Physiol 2022; 322:G513-G522. [PMID: 35170350 PMCID: PMC8993533 DOI: 10.1152/ajpgi.00347.2021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Previous studies have shown that pharmacological manipulations with stress-related hormones such as corticotropin-releasing factor and thyrotropin-releasing hormone induce neuroplasticity in brainstem vagal neurocircuits, which modulate gastric tone and motility. The prototypical antistress hormone oxytocin (OXT) has been shown to modulate gastric tone and motility via vagal pathways, and descending hypothalamic oxytocinergic inputs play a major role in the vagally dependent gastric-related adaptations to stress. The aim of this study was to investigate the possible cellular mechanisms through which OXT modulates central vagal brainstem and peripheral enteric neurocircuits of male Sprague-Dawley rats in response to chronic repetitive stress. After chronic (5 consecutive days) of homotypic or heterotypic stress load, the response to exogenous brainstem administration of OXT was examined using whole cell patch-clamp recordings from gastric-projecting vagal motoneurons and in vivo recordings of gastric tone and motility. GABAergic currents onto vagal motoneurons were decreased by OXT in stressed, but not in naïve rats. In naïve rats, microinjections of OXT in vagal brainstem nuclei-induced gastroinhibition via peripheral release of nitric oxide (NO). In stressed rats, however, the OXT-induced gastroinhibition was determined by the release of both NO and vasoactive intestinal peptide (VIP). Taken together, our data indicate that stress induces neuroplasticity in the response to OXT in the neurocircuits, which modulate gastric tone and motility. In particular, stress uncovers the OXT-mediated modulation of brainstem GABAergic currents and alters the peripheral gastric response to vagal stimulation.NEW & NOTEWORTHY The prototypical antistress hormone, oxytocin (OXT), modulates gastric tone and motility via vagal pathways, and descending hypothalamic-brainstem OXT neurocircuits play a major role in the vagally dependent adaptation of gastric motility and tone to stress. The current study suggests that in the neurocircuits, which modulate gastric tone and motility, stress induces neuroplasticity in the response to OXT and may reflect the dysregulation observed in stress-exacerbated functional motility disorders.
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Affiliation(s)
- Yanyan Jiang
- 1Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
| | | | - Kirsteen N. Browning
- 1Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
| | - R. Alberto Travagli
- 1Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
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Gillis RA, Dezfuli G, Bellusci L, Vicini S, Sahibzada N. Brainstem Neuronal Circuitries Controlling Gastric Tonic and Phasic Contractions: A Review. Cell Mol Neurobiol 2022; 42:333-360. [PMID: 33813668 PMCID: PMC9595174 DOI: 10.1007/s10571-021-01084-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 03/18/2021] [Indexed: 11/30/2022]
Abstract
This review is on how current knowledge of brainstem control of gastric mechanical function unfolded over nearly four decades from the perspective of our research group. It describes data from a multitude of different types of studies involving retrograde neuronal tracing, microinjection of drugs, whole-cell recordings from rodent brain slices, receptive relaxation reflex, accommodation reflex, c-Fos experiments, immunohistochemical methods, electron microscopy, transgenic mice, optogenetics, and GABAergic signaling. Data obtained indicate the following: (1) nucleus tractus solitarius (NTS)-dorsal motor nucleus of the vagus (DMV) noradrenergic connection is required for reflex control of the fundus; (2) second-order nitrergic neurons in the NTS are also required for reflex control of the fundus; (3) a NTS GABAergic connection is required for reflex control of the antrum; (4) a single DMV efferent pathway is involved in brainstem control of gastric mechanical function under most experimental conditions excluding the accommodation reflex. Dual-vagal effectors controlling cholinergic and non-adrenergic and non-cholinergic (NANC) input to the stomach may be part of the circuitry of this reflex. (5) GABAergic signaling within the NTS via Sst-GABA interneurons determine the basal (resting) state of gastric tone and phasic contractions. (6) For the vagal-vagal reflex to become operational, an endogenous opioid in the NTS is released and the activity of Sst-GABA interneurons is suppressed. From the data, we suggest that the CNS has the capacity to provide region-specific control over the proximal (fundus) and distal (antrum) stomach through engaging phenotypically different efferent inputs to the DMV.
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Affiliation(s)
- Richard A. Gillis
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20007, USA
| | - Ghazaul Dezfuli
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20007, USA
| | - Lorenza Bellusci
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20007, USA
| | - Stefano Vicini
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, 20007, USA.
| | - Niaz Sahibzada
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC 20007, USA
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Komisaruk BR, Frangos E. Vagus nerve afferent stimulation: Projection into the brain, reflexive physiological, perceptual, and behavioral responses, and clinical relevance. Auton Neurosci 2021; 237:102908. [PMID: 34823149 DOI: 10.1016/j.autneu.2021.102908] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 11/01/2021] [Accepted: 11/06/2021] [Indexed: 12/26/2022]
Abstract
The afferent vagus nerves project to diverse neural networks within the brainstem and forebrain, based on neuroanatomical, neurophysiological, and functional (fMRI) brain imaging evidence. In response to afferent vagal stimulation, multiple homeostatic visceral reflexes are elicited. Physiological stimuli and both invasive and non-invasive electrical stimulation that activate the afferent vagus elicit perceptual and behavioral responses that are of physiological and clinical significance. In the present review, we address these multiple roles of the afferent vagus under normal and pathological conditions, based on both animal and human evidence.
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Affiliation(s)
- Barry R Komisaruk
- Department of Psychology, Rutgers, The State University of New Jersey, Newark, NJ 07102, United States.
| | - Eleni Frangos
- National Center for Complementary and Integrative Health, National Institutes of Health, Bethesda, MD 20892, United States
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10
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Worth AA, Luckman SM. Do oxytocin neurones affect feeding? J Neuroendocrinol 2021; 33:e13035. [PMID: 34495565 DOI: 10.1111/jne.13035] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 07/30/2021] [Accepted: 08/19/2021] [Indexed: 12/24/2022]
Abstract
There has been a long history of research on the effects of oxytocin on feeding behaviour. The classic-held view is that the neurohormone is anorexigenic at least in rodents, although the data for humans are not so clear cut. Likewise, a physiological role for oxytocin is disputed. Thus, although pharmacological, anatomical and physiological data suggest oxytocin may have a function in satiety signalling, this view is not supported by the latest research using the genetic recording and manipulation of oxytocin neurones. Here, we avoid a discussion of the pharmacological effects of oxytocin and examine evidence, from both sides of the argument, concerning whether the endogenous oxytocin system has a role in the regulation of normal feeding.
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Affiliation(s)
- Amy A Worth
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
| | - Simon M Luckman
- Faculty of Biology, Medicine and Health, University of Manchester, Manchester, UK
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11
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Bülbül M, Sinen O. Sexual dimorphism in maternally separated rats: effects of repeated homotypic stress on gastrointestinal motor functions. Exp Brain Res 2021; 239:2551-2560. [PMID: 34160630 DOI: 10.1007/s00221-021-06151-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/08/2021] [Indexed: 11/30/2022]
Abstract
Experiencing stressful events during early life has been considered as a risk factor for development of functional gastrointestinal disorders in adulthood. This study aimed to investigate the sex-related differences in stress-induced gastrointestinal (GI) dysmotility in rats exposed to neonatal maternal separation (MS). Newborn pups were removed from mothers for 180 min from postnatal day-1 to day-14. Experiments were performed in male and female offsprings at adulthood. Elevated plus maze (EPM) test was used to assess MS-induced anxiety-like behaviors. Ninety minute of restraint stress was applied for once or 5 consecutive days for acute stress (AS) or repeated homotypic stress (RHS), respectively. Measurement of fecal output (FO) and gastric emptying (GE), and hypothalamic microdialysis were performed. Both in males and females, MS produced anxiety-like behaviors. AS delayed GE and increased FO in all groups. In RHS-loaded MS females, AS-induced alterations in GE and FO were restored, however, no adaptation was observed in male counterparts. Regardless of sex and neonatal stress experience, AS significantly increased corticotropin-releasing factor (CRF) release from paraventricular nucleus of hypothalamus, whereas females were found more susceptible than males. Following RHS, AS-induced elevations in CRF release were attenuated only in MS females, but not in males. Both females and males seem to be prone to AS-induced alterations in hypothalamic CRF system and in GI motor functions. Neonatal MS disturbs chronic stress coping mechanisms in males. Conversely, females are likely to circumvent the deleterious effects of neonatal MS on GI functions through developing a habituation to prolonged stressed conditions.
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Affiliation(s)
- Mehmet Bülbül
- Department of Physiology, Faculty of Medicine, Akdeniz University, Antalya, 07070, Turkey.
| | - Osman Sinen
- Department of Physiology, Faculty of Medicine, Akdeniz University, Antalya, 07070, Turkey
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12
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Tolentino Bento da Silva M, Palheta-Junior RC, Silva CMS, Cavalcante AKM, Quetz JDS, Havt A, de Lima JBM, Mecawi ADS, de Castro M, Antunes-Rodrigues J, de Oliveira RB, Magalhães PJC, Aguiar Dos Santos A. Role of cholecystokinin and oxytocin in slower gastric emptying induced by physical exercise in rats. Physiol Behav 2021; 233:113355. [PMID: 33571545 DOI: 10.1016/j.physbeh.2021.113355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Revised: 02/03/2021] [Accepted: 02/05/2021] [Indexed: 11/23/2022]
Abstract
Vigorous exercise can induce gastrointestinal disorders such decreased gastric emptying pace, while low-intensity exercise can accelerate gastric motility. However, the mechanisms of these effects are still unknown. We investigated the possible neurohumoral mechanisms involved in these phenomena. In sedentary (Sed) and acute exercise (Ex) groups of rats, we assessed the activation of c-Fos in NTS and DVMN and the plasma levels of CCK and OXT. Separate groups received pretreatment with the oxytocin antagonist atosiban (AT), the cholecystokinin antagonist devazepide (DVZ), or the TRPV1 receptor inhibitor capsazepine (CAPZ). AT, DVZ and CAPZ treatments prevented (p<0.05) slower gastric emptying induced by acute exercise. The gene expression of OXT decreased (P<0.05) while that of CCK increased (P<0.05) in the gastric fundus and pylorus of the Ex group, while the plasma levels of OXT rose (p<0.05) and of CCK declined (p<5.05). We also observed activation (p<0.05) of c-Fos-sensitive neurons in the NTS and DVMN of exercised rats. In conclusion, acute exercise slowed gastric emptying by the vagal afferent pathway, which involved activation of CCK1/OXT/TRPV1 sensitivity.
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Affiliation(s)
| | | | - Camila Meirelles Souza Silva
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | | | - Josiane da Silva Quetz
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | - Alexandre Havt
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | | | - André de Souza Mecawi
- Department of Biophisics, Palista School of Medicine, Federal University of São Paulo, São Paulo, SP, Brazil
| | - Margaret de Castro
- School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - José Antunes-Rodrigues
- School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP, Brazil
| | | | - Pedro Jorge Caldas Magalhães
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
| | - Armenio Aguiar Dos Santos
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, CE, Brazil
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13
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Browning KN, Carson KE. Central Neurocircuits Regulating Food Intake in Response to Gut Inputs-Preclinical Evidence. Nutrients 2021; 13:nu13030908. [PMID: 33799575 PMCID: PMC7998662 DOI: 10.3390/nu13030908] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 03/02/2021] [Accepted: 03/07/2021] [Indexed: 02/07/2023] Open
Abstract
The regulation of energy balance requires the complex integration of homeostatic and hedonic pathways, but sensory inputs from the gastrointestinal (GI) tract are increasingly recognized as playing critical roles. The stomach and small intestine relay sensory information to the central nervous system (CNS) via the sensory afferent vagus nerve. This vast volume of complex sensory information is received by neurons of the nucleus of the tractus solitarius (NTS) and is integrated with responses to circulating factors as well as descending inputs from the brainstem, midbrain, and forebrain nuclei involved in autonomic regulation. The integrated signal is relayed to the adjacent dorsal motor nucleus of the vagus (DMV), which supplies the motor output response via the efferent vagus nerve to regulate and modulate gastric motility, tone, secretion, and emptying, as well as intestinal motility and transit; the precise coordination of these responses is essential for the control of meal size, meal termination, and nutrient absorption. The interconnectivity of the NTS implies that many other CNS areas are capable of modulating vagal efferent output, emphasized by the many CNS disorders associated with dysregulated GI functions including feeding. This review will summarize the role of major CNS centers to gut-related inputs in the regulation of gastric function with specific reference to the regulation of food intake.
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14
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Blanke EN, Holmes GM, Besecker EM. Altered physiology of gastrointestinal vagal afferents following neurotrauma. Neural Regen Res 2021; 16:254-263. [PMID: 32859772 PMCID: PMC7896240 DOI: 10.4103/1673-5374.290883] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The adaptability of the central nervous system has been revealed in several model systems. Of particular interest to central nervous system-injured individuals is the ability for neural components to be modified for regain of function. In both types of neurotrauma, traumatic brain injury and spinal cord injury, the primary parasympathetic control to the gastrointestinal tract, the vagus nerve, remains anatomically intact. However, individuals with traumatic brain injury or spinal cord injury are highly susceptible to gastrointestinal dysfunctions. Such gastrointestinal dysfunctions attribute to higher morbidity and mortality following traumatic brain injury and spinal cord injury. While the vagal efferent output remains capable of eliciting motor responses following injury, evidence suggests impairment of the vagal afferents. Since sensory input drives motor output, this review will discuss the normal and altered anatomy and physiology of the gastrointestinal vagal afferents to better understand the contributions of vagal afferent plasticity following neurotrauma.
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Affiliation(s)
- Emily N Blanke
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, USA
| | - Gregory M Holmes
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, USA
| | - Emily M Besecker
- Department of Health Sciences, Gettysburg College, Gettysburg, PA, USA
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15
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Jiang Y, Travagli RA. Hypothalamic-vagal oxytocinergic neurocircuitry modulates gastric emptying and motility following stress. J Physiol 2020; 598:4941-4955. [PMID: 32864736 PMCID: PMC8451654 DOI: 10.1113/jp280023] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 07/27/2020] [Indexed: 12/30/2022] Open
Abstract
KEY POINTS Stress triggers and exacerbates the symptoms of functional gastrointestinal disorders, such as delayed gastric emptying and impaired gastric motility. Understanding the mechanisms by which the neural circuits, impaired by stress, are restored may help to identify potential targets for more effective therapeutic interventions. Oxytocin administration or release ameliorates the stress-induced delayed gastric emptying and motility. However, is it unclear whether the effects are mediated via the hypothalamic-pituitary-adrenocortical axis or the oxytocinergic projections from the paraventricular nucleus of the hypothalamus to brainstem neurones of the dorsal vagal complex. We used Cre-inducible designer receptors exclusively activated by designer drugs to demonstrate the fundamental role of the oxytocinergic hypothalamic-vagal projections in the gastric adaptation to stress. ABSTRACT Stress triggers and exacerbates the symptoms of functional gastrointestinal (GI) disorders, such as delayed gastric emptying and impaired gastric motility. The prototypical anti-stress hormone, oxytocin (OXT), plays a major role in the modulation of gastric emptying and motility following stress. It is not clear, however, whether the amelioration of dysregulated GI functions by OXT is mediated via an effect on the hypothalamic-pituitary-adrenocortical axis or the oxytocinergic projections from the paraventricular nucleus of the hypothalamus (PVN) to neurones of the dorsal vagal complex (DVC). In the present study we tested the hypothesis that the activity of hypothalamic-vagal oxytocinergic neurocircuits plays a major role in the gastric adaptation to stress. Cre-inducible designer receptors exclusively activated by designer drugs (DREADDs) were injected into the DVC of rats and retrogradely transported to allow selective expression in OXT neurones in the PVN. Following acute stress and either chronic heterotypic (CHe) or chronic homotypic (CHo) stress, gastric emptying was assessed via the [13 C]-octanoic acid breath test, and gastric tone and motility were assessed via strain gauges sewn on the surface of the stomach. Activation of the hypothalamic-vagal oxytocinergic neurocircuitry, by DREADD agonist clozapine-N-oxide (CNO), prevented the delayed gastric emptying observed following acute or CHe stress, and 4th ventricular administration of CNO increased gastric tone and motility. Conversely, CNO-mediated inhibition of the hypothalamic-vagal oxytocinergic neurocircuitry prevented the CHo-induced adaptation in gastric emptying, and an increase in gastric tone and motility. Taken together, the data support the hypothesis that hypothalamic-vagal oxytocinergic neurocircuits play a major role in the modulation of gastric emptying and motility following stress.
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Affiliation(s)
- Yanyan Jiang
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA
| | - R Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA
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16
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Yu Z. Neuromechanism of acupuncture regulating gastrointestinal motility. World J Gastroenterol 2020; 26:3182-3200. [PMID: 32684734 PMCID: PMC7336328 DOI: 10.3748/wjg.v26.i23.3182] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Revised: 03/29/2020] [Accepted: 05/23/2020] [Indexed: 02/06/2023] Open
Abstract
Acupuncture has been used in China for thousands of years and has become more widely accepted by doctors and patients around the world. A large number of clinical studies and animal experiments have confirmed that acupuncture has a benign adjustment effect on gastrointestinal (GI) movement; however, the mechanism of this effect is unclear, especially in terms of neural mechanisms, and there are still many areas that require further exploration. This article reviews the recent data on the neural mechanism of acupuncture on GI movements. We summarize the neural mechanism of acupuncture on GI movement from four aspects: acupuncture signal transmission, the sympathetic and parasympathetic nervous system, the enteric nervous system, and the central nervous system.
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Affiliation(s)
- Zhi Yu
- Key Laboratory of Acupuncture and Medicine Research of Ministry of Education, Nanjing University of Chinese Medicine, Nanjing 210023, Jiangsu Province, China
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17
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Cruz MT, Dezfuli G, Murphy EC, Vicini S, Sahibzada N, Gillis RA. GABA B Receptor Signaling in the Dorsal Motor Nucleus of the Vagus Stimulates Gastric Motility via a Cholinergic Pathway. Front Neurosci 2019; 13:967. [PMID: 31572117 PMCID: PMC6751316 DOI: 10.3389/fnins.2019.00967] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Accepted: 08/28/2019] [Indexed: 12/21/2022] Open
Abstract
Central nervous system regulation of the gastric tone and motility is primarily mediated via preganglionic neurons of the dorsal motor nucleus of the vagus (DMV). This is thought to occur by simultaneous engagement of both independent excitatory and inhibitory pathways from the DMV and has been proposed to underlie the opposing effects seen on gastric tone and motility in a number of in vivo models. Contrary to this view, we have been unable to find any evidence for this "dual effector" pathway. Since this possibility is so fundamental to how the brain-gut axis may interact in light of both peripheral and central demands, we decided to explore it further in two separate animal models previously used in conjunction with GABAB signaling to report the existence of a "dual effector" pathway. Using anesthetized rats or ferrets, we microinjected baclofen (7.5 pmol; n = 6), a GABAB agonist into the DMV of rats or intravenously administered it (0.5 mg/kg; n = 4) in ferrets. In rats, unilateral microinjection of baclofen into the DMV caused a robust dose-dependent increase in gastric tone and motility that was abolished by ipsilateral vagotomy and counteracted by pretreatment with atropine (0.1 mg/kg; IV). Similarly, as microinjection in the rats, IV administration of baclofen (0.5 mg/kg) in the ferrets induced its characteristic excitatory effects on gastric tone and motility, which were blocked by either pre- or post-treatment with atropine (0.1 mg/kg; IV). Altogether, our data provide evidence that the gastric musculature (other than the gastric sphincters) is regulated by a "single effector" DMV pathway using acetylcholine.
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Affiliation(s)
| | | | | | | | - Niaz Sahibzada
- Department of Pharmacology and Physiology, Georgetown University Medical Center, Washington, DC, United States
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18
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Jiang Y, Greenwood-Van Meerveld B, Johnson AC, Travagli RA. Role of estrogen and stress on the brain-gut axis. Am J Physiol Gastrointest Liver Physiol 2019; 317:G203-G209. [PMID: 31241977 PMCID: PMC6734369 DOI: 10.1152/ajpgi.00144.2019] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 06/19/2019] [Accepted: 06/19/2019] [Indexed: 01/31/2023]
Abstract
Symptoms of functional gastrointestinal disorders (FGIDs), including fullness, bloating, abdominal pain, and altered gastrointestinal (GI) motility, present a significant clinical problem, with a reported prevalence of 25%-40% within the general population. More than 60% of those affected seek and require healthcare, and affected individuals report a significantly decreased quality of life. FGIDs are highly correlated with episodes of acute and chronic stress and are increased in prevalence and reported severity in women compared with men. Although there is evidence that sex and stress interact to exacerbate FGID symptoms, the physiological mechanisms that mediate these sex-dependent disparities are incompletely understood, although hormonal-related differences in GI motility and visceral sensitivity have been purported to play a significant role in the etiology. In this mini review, we will discuss brain-gut axis control of GI motility and sensitivity, the influence of estrogen on GI motility and sensitivity, and stress modulation of the brain-gut axis.
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Affiliation(s)
- Yanyan Jiang
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
| | - Beverley Greenwood-Van Meerveld
- Oklahoma Center for Neuroscience, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma
- Veterans Affairs Health Care System, Oklahoma City, Oklahoma
| | - Anthony C Johnson
- Veterans Affairs Health Care System, Oklahoma City, Oklahoma
- Department of Neurology, University of Oklahoma Health Science Center, Oklahoma City, Oklahoma
| | - R Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
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19
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Odekunle EA, Semmens DC, Martynyuk N, Tinoco AB, Garewal AK, Patel RR, Blowes LM, Zandawala M, Delroisse J, Slade SE, Scrivens JH, Egertová M, Elphick MR. Ancient role of vasopressin/oxytocin-type neuropeptides as regulators of feeding revealed in an echinoderm. BMC Biol 2019; 17:60. [PMID: 31362737 PMCID: PMC6668147 DOI: 10.1186/s12915-019-0680-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/09/2019] [Indexed: 12/25/2022] Open
Abstract
BACKGROUND Vasopressin/oxytocin (VP/OT)-type neuropeptides are well known for their roles as regulators of diuresis, reproductive physiology and social behaviour. However, our knowledge of their functions is largely based on findings from studies on vertebrates and selected protostomian invertebrates. Little is known about the roles of VP/OT-type neuropeptides in deuterostomian invertebrates, which are more closely related to vertebrates than protostomes. RESULTS Here, we have identified and functionally characterised a VP/OT-type signalling system comprising the neuropeptide asterotocin and its cognate G-protein coupled receptor in the starfish (sea star) Asterias rubens, a deuterostomian invertebrate belonging to the phylum Echinodermata. Analysis of the distribution of asterotocin and the asterotocin receptor in A. rubens using mRNA in situ hybridisation and immunohistochemistry revealed expression in the central nervous system (radial nerve cords and circumoral nerve ring), the digestive system (including the cardiac stomach) and the body wall and associated appendages. Informed by the anatomy of asterotocin signalling, in vitro pharmacological experiments revealed that asterotocin acts as a muscle relaxant in starfish, contrasting with the myotropic actions of VP/OT-type neuropeptides in vertebrates. Furthermore, in vivo injection of asterotocin had a striking effect on starfish behaviour-triggering fictive feeding where eversion of the cardiac stomach and changes in body posture resemble the unusual extra-oral feeding behaviour of starfish. CONCLUSIONS We provide a comprehensive characterisation of VP/OT-type signalling in an echinoderm, including a detailed anatomical analysis of the expression of both the VP/OT-type neuropeptide asterotocin and its cognate receptor. Our discovery that asterotocin triggers fictive feeding in starfish provides important new evidence of an evolutionarily ancient role of VP/OT-type neuropeptides as regulators of feeding in animals.
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Affiliation(s)
- Esther A. Odekunle
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Dean C. Semmens
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Nataly Martynyuk
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
- Department of Clinical Neurosciences, MRC Cambridge Stem Cell Institute, University of Cambridge, Cambridge, CB2 0SZ UK
| | - Ana B. Tinoco
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Abdullah K. Garewal
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Radhika R. Patel
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Liisa M. Blowes
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Meet Zandawala
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
- Department of Neuroscience, Brown University, Providence, USA
| | - Jérôme Delroisse
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
- Research Institute for Biosciences, Biology of Marine Organisms and Biomimetics, University of Mons (UMONS), 7000 Mons, Belgium
| | - Susan E. Slade
- Waters/Warwick Centre for BioMedical Mass Spectrometry and Proteomics, School of Life Sciences, University of Warwick, Coventry, CV4 7AL UK
- Waters Corporation, Stamford Avenue, Altrincham Road, Wilmslow, SK9 4AX UK
| | - James H. Scrivens
- Waters/Warwick Centre for BioMedical Mass Spectrometry and Proteomics, School of Life Sciences, University of Warwick, Coventry, CV4 7AL UK
- School of Science, Engineering & Design, Teesside University, Stephenson Street, Tees Valley, TS1 3BA UK
| | - Michaela Egertová
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
| | - Maurice R. Elphick
- School of Biological & Chemical Sciences, Queen Mary University of London, Mile End Road, London, E1 4NS UK
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20
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Page SJ, Zhu M, Appleyard SM. Effects of acute and chronic nicotine on catecholamine neurons of the nucleus of the solitary tract. Am J Physiol Regul Integr Comp Physiol 2018; 316:R38-R49. [PMID: 30354182 DOI: 10.1152/ajpregu.00344.2017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nicotine is an addictive drug that has broad effects throughout the brain. One site of action is the nucleus of the solitary tract (NTS), where nicotine initiates a stress response and modulates cardiovascular and gastric function through nicotinic acetylcholine receptors (nAChRs). Catecholamine (CA) neurons in the NTS influence stress and gastric and cardiovascular reflexes, making them potential mediators of nicotine's effects; however nicotine's effect on these neurons is unknown. Here, we determined nicotine's actions on NTS-CA neurons by use of patch-clamp techniques in brain slices from transgenic mice expressing enhanced green fluorescent protein driven by the tyrosine hydroxylase promoter (TH-EGFP). Picospritzing nicotine both induced a direct inward current and increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs) in NTS-CA neurons, effects blocked by nonselective nAChR antagonists TMPH and MLA. The increase in sEPSC frequency was mimicked by nAChRα7 agonist AR-R17779 and blocked by nAChRα7 antagonist MG624. AR-R17779 also increased the firing of TH-EGFP neurons, an effect dependent on glutamate inputs, as it was blocked by the glutamate antagonist NBQX. In contrast, the nicotine-induced current was mimicked by nAChRα4β2 agonist RJR2403 and blocked by nAChRα4β2 antagonist DHβE. RJR2403 also increased the firing rate of TH-EGFP neurons independently of glutamate. Finally, both somatodendritic and sEPSC nicotine responses from NTS-CA neurons were larger in nicotine-dependent mice that had under gone spontaneous nicotine withdrawal. These results demonstrate that 1) nicotine activates NTS-CA neurons both directly, by inducing a direct current, and indirectly, by increasing glutamate inputs, and 2) NTS-CA nicotine responsiveness is altered during nicotine withdrawal.
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Affiliation(s)
- Stephen J Page
- Program in Neuroscience, Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, Washington
| | - Mingyan Zhu
- Program in Neuroscience, Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, Washington
| | - Suzanne M Appleyard
- Program in Neuroscience, Department of Integrative Physiology and Neuroscience, Washington State University , Pullman, Washington
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21
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Jiang Y, Coleman FH, Kopenhaver Doheny K, Travagli RA. Stress Adaptation Upregulates Oxytocin within Hypothalamo-Vagal Neurocircuits. Neuroscience 2018; 390:198-205. [PMID: 30176320 DOI: 10.1016/j.neuroscience.2018.08.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Revised: 08/20/2018] [Accepted: 08/21/2018] [Indexed: 12/16/2022]
Abstract
Stress plays a pivotal role in the development and/or exacerbation of functional gastrointestinal (GI) disorders. The paraventricular nucleus of the hypothalamus (PVN) contains neurons that are part of the hypothalamic-pituitary-adrenal axis as well as preautonomic neurons innervating, among other areas, gastric-projecting preganglionic neurons of the dorsal vagal complex (DVC). The aim of the present study was to test the hypothesis that stress adaptation upregulates oxytocin (OXT) within PVN-brainstem vagal neurocircuitry. The retrograde tracer cholera toxin B (CTB) was injected into the DVC of rats which, after post-surgical recovery, were pair-housed and exposed to either homo- or heterotypic stress for five consecutive days. Fecal pellets were counted at the end of each stress load. Two hours after the last stressor, the whole brain was excised. Brainstem and hypothalamic nuclei were analyzed immunohistochemically for the presence of both OXT-immunopositive cells in identified preautonomic PVN neurons as well as OXT fibers in the DVC. Rats exposed to chronic homotypic, but not chronic heterotypic stress, had a significant increase in both number of CTB+ OXT co-localized neurons in the PVN as well as density of OXT-positive fibers in the DVC compared to control rats. These data suggest that preautonomic OXT PVN neurons and their projections to the DVC increase following adaptation to stress, and suggest that the possible up-regulation of OXT within PVN-brainstem vagal neurocircuitry may play a role in the adaptation of GI responses to stress.
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Affiliation(s)
- Yanyan Jiang
- Department of Neural and Behavioral Sciences, Penn State - College of Medicine, Hershey, PA, USA
| | - F Holly Coleman
- Department of Neural and Behavioral Sciences, Penn State - College of Medicine, Hershey, PA, USA
| | | | - R Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State - College of Medicine, Hershey, PA, USA.
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22
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Freeman SM, Ngo J, Singh B, Masnaghetti M, Bales KL, Blevins JE. Effects of Chronic Oxytocin Administration and Diet Composition on Oxytocin and Vasopressin 1a Receptor Binding in the Rat Brain. Neuroscience 2018; 392:241-251. [PMID: 30071278 DOI: 10.1016/j.neuroscience.2018.07.037] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2018] [Revised: 07/19/2018] [Accepted: 07/20/2018] [Indexed: 12/19/2022]
Abstract
Oxytocin (OT) elicits weight loss in diet-induced obese (DIO) rodents, nonhuman primates, and humans, in part, by reducing food intake. Chronic OT administration produces more sustained weight loss in high-fat diet (HFD)-fed DIO rodents relative to chow-fed controls, but the reasons for this effect remain unclear. We hypothesized that HFD-induced obesity is associated with elevated OT receptor (OXTR) binding in brain regions where OT is known to cause decreased food intake and that this sensitized neural system is one mechanism by which OT preferentially elicits weight loss in DIO rodents. We therefore determined the impact of diet (HFD vs chow) and drug treatment (chronic OT infusion vs vehicle) on (1) OXTR binding in hindbrain and forebrain sites where OT suppresses food intake relative to control sites that express OXTR and (2) forebrain vasopressin 1a receptor (AVPR1a) density to evaluate the specificity of any OT effects. Using quantitative receptor autoradiography, we found that (1) diet composition failed to alter OXTR or AVPR1a binding; (2) chronic OT treatment produced largely global reductions in forebrain OXTR and AVPR1a binding without significantly altering hindbrain OXTR binding. These findings suggest that forebrain OXTR and AVPR1a are down-regulated in response to chronic OT treatment. Given that chronic intranasal OT may be used as a therapeutic strategy to treat obesity, future studies should consider the potential downregulatory effect that chronic treatment can have across forebrain and hindbrain nonapeptide receptors and assess the potential contribution of both receptor subtypes to the outcome measures.
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Affiliation(s)
- Sara M Freeman
- Department of Psychology, University of California, Davis, CA, USA
| | - Julie Ngo
- Department of Psychology, University of California, Davis, CA, USA
| | - Bhavdeep Singh
- Department of Psychology, University of California, Davis, CA, USA
| | | | - Karen L Bales
- Department of Psychology, University of California, Davis, CA, USA
| | - James E Blevins
- VA Puget Sound Health Care System, Office of Research and Development Medical Research Service, Department of Veterans Affairs Medical Center, Seattle, WA 98108, USA; Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.
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23
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Ong ZY, Bongiorno DM, Hernando MA, Grill HJ. Effects of Endogenous Oxytocin Receptor Signaling in Nucleus Tractus Solitarius on Satiation-Mediated Feeding and Thermogenic Control in Male Rats. Endocrinology 2017; 158:2826-2836. [PMID: 28575174 PMCID: PMC5659667 DOI: 10.1210/en.2017-00200] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Accepted: 05/24/2017] [Indexed: 12/15/2022]
Abstract
Central oxytocin receptor (OT-R) signaling reduces food intake and increases energy expenditure, but the central sites and mechanisms mediating these effects are unresolved. We showed previously that pharmacological activation of OT-R in hindbrain/nucleus tractus solitarius (NTS) amplifies the intake-inhibitory effects of gastrointestinal (GI) satiation signals. Unexplored were the energetic effects of hindbrain OT-R agonism and the physiological relevance of NTS OT-R signaling on food intake and energy expenditure control. Using a virally mediated OT-R knockdown (KD) strategy and a range of behavioral paradigms, this study examined the role of endogenous NTS OT-R signaling on satiation-mediated food intake inhibition and thermogenic control. Results showed that, compared with controls, NTS OT-R KD rats consumed larger meals, were less responsive to the intake-inhibitory effects of a self-ingested preload, and consumed more chow following a 24-hour fast. These data indicate that NTS OT-R signaling is necessary for normal satiation control. Whereas both control and NTS OT-R KD rats increased core temperature following high-fat diet maintenance (relative to chow maintenance), the percent increase in core temperature was greater in control compared with NTS OT-R KD rats during the light cycle. Hindbrain oxytocin agonist delivery increased core temperature in both control and NTS OT-R KD rats and the percent increase relative to vehicle treatment was not significantly different between groups. Together, data reveal a critical role for endogenous NTS OT-R signaling in mediating the intake-inhibitory effects of endogenous GI satiation signals and in diet-induced thermogenesis.
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Affiliation(s)
- Zhi Yi Ong
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Diana M. Bongiorno
- Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Mary Ann Hernando
- Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104
| | - Harvey J. Grill
- Department of Psychology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
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24
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McMenamin CA, Travagli RA, Browning KN. Inhibitory neurotransmission regulates vagal efferent activity and gastric motility. Exp Biol Med (Maywood) 2017; 241:1343-50. [PMID: 27302177 DOI: 10.1177/1535370216654228] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The gastrointestinal tract receives extrinsic innervation from both the sympathetic and parasympathetic nervous systems, which regulate and modulate the function of the intrinsic (enteric) nervous system. The stomach and upper gastrointestinal tract in particular are heavily influenced by the parasympathetic nervous system, supplied by the vagus nerve, and disruption of vagal sensory or motor functions results in disorganized motility patterns, disrupted receptive relaxation and accommodation, and delayed gastric emptying, amongst others. Studies from several laboratories have shown that the activity of vagal efferent motoneurons innervating the upper GI tract is inhibited tonically by GABAergic synaptic inputs from the adjacent nucleus tractus solitarius. Disruption of this influential central GABA input impacts vagal efferent output, hence gastric functions, significantly. The purpose of this review is to describe the development, physiology, and pathophysiology of this functionally dominant inhibitory synapse and its role in regulating vagally determined gastric functions.
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Affiliation(s)
- Caitlin A McMenamin
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, USA
| | - R Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, USA
| | - Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, USA
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25
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Leng G, Sabatier N. Oxytocin - The Sweet Hormone? Trends Endocrinol Metab 2017; 28:365-376. [PMID: 28283319 DOI: 10.1016/j.tem.2017.02.007] [Citation(s) in RCA: 60] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 02/07/2017] [Accepted: 02/10/2017] [Indexed: 12/14/2022]
Abstract
Mammalian neurons that produce oxytocin and vasopressin apparently evolved from an ancient cell type with both sensory and neurosecretory properties that probably linked reproductive functions to energy status and feeding behavior. Oxytocin in modern mammals is an autocrine/paracrine regulator of cell function, a systemic hormone, a neuromodulator released from axon terminals within the brain, and a 'neurohormone' that acts at receptors distant from its site of release. In the periphery oxytocin is involved in electrolyte homeostasis, gastric motility, glucose homeostasis, adipogenesis, and osteogenesis, and within the brain it is involved in food reward, food choice, and satiety. Oxytocin preferentially suppresses intake of sweet-tasting carbohydrates while improving glucose tolerance and supporting bone remodeling, making it an enticing translational target.
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Affiliation(s)
- Gareth Leng
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK.
| | - Nancy Sabatier
- Centre for Integrative Physiology, The University of Edinburgh, Edinburgh UK
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Grabauskas G, Owyang C. Plasticity of vagal afferent signaling in the gut. MEDICINA-LITHUANIA 2017; 53:73-84. [PMID: 28454890 PMCID: PMC6318799 DOI: 10.1016/j.medici.2017.03.002] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 03/21/2017] [Indexed: 12/13/2022]
Abstract
Vagal sensory neurons mediate the vago-vagal reflex which, in turn, regulates a wide array of gastrointestinal functions including esophageal motility, gastric accommodation and pancreatic enzyme secretion. These neurons also transmit sensory information from the gut to the central nervous system, which then mediates the sensations of nausea, fullness and satiety. Recent research indicates that vagal afferent neurons process non-uniform properties and a significant degree of plasticity. These properties are important to ensure that vagally regulated gastrointestinal functions respond rapidly and appropriately to various intrinsic and extrinsic factors. Similar plastic changes in the vagus also occur in pathophysiological conditions, such as obesity and diabetes, resulting in abnormal gastrointestinal functions. A clear understanding of the mechanisms which mediate these events may provide novel therapeutic targets for the treatment of gastrointestinal disorders due to vago-vagal pathway malfunctions.
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Affiliation(s)
- Gintautas Grabauskas
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48019, USA.
| | - Chung Owyang
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48019, USA
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Quintana DS, Dieset I, Elvsåshagen T, Westlye LT, Andreassen OA. Oxytocin system dysfunction as a common mechanism underlying metabolic syndrome and psychiatric symptoms in schizophrenia and bipolar disorders. Front Neuroendocrinol 2017; 45:1-10. [PMID: 28049009 DOI: 10.1016/j.yfrne.2016.12.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2016] [Revised: 12/14/2016] [Accepted: 12/29/2016] [Indexed: 12/24/2022]
Abstract
There is growing interest in using intranasal oxytocin (OT) to treat social dysfunction in schizophrenia and bipolar disorders (i.e., psychotic disorders). While OT treatment results have been mixed, emerging evidence suggests that OT system dysfunction may also play a role in the etiology of metabolic syndrome (MetS), which appears in one-third of individuals with psychotic disorders and associated with increased mortality. Here we examine the evidence for a potential role of the OT system in the shared risk for MetS and psychotic disorders, and its prospects for ameliorating MetS. Using several studies to demonstrate the overlapping neurobiological profiles of metabolic risk factors and psychiatric symptoms, we show that OT system dysfunction may be one common mechanism underlying MetS and psychotic disorders. Given the critical need to better understand metabolic dysregulation in these disorders, future OT trials assessing behavioural and cognitive outcomes should additionally include metabolic risk factor parameters.
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Affiliation(s)
- Daniel S Quintana
- NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, University of Oslo, and Oslo University Hospital, Oslo, Norway.
| | - Ingrid Dieset
- NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, University of Oslo, and Oslo University Hospital, Oslo, Norway
| | - Torbjørn Elvsåshagen
- NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, University of Oslo, and Oslo University Hospital, Oslo, Norway; Department of Neurology, Oslo University Hospital, Oslo, Norway; Institute of Clinical Medicine, University of Oslo, Oslo, Norway
| | - Lars T Westlye
- NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, University of Oslo, and Oslo University Hospital, Oslo, Norway; Department of Psychology, University of Oslo, Oslo, Norway
| | - Ole A Andreassen
- NORMENT, KG Jebsen Centre for Psychosis Research, Division of Mental Health and Addiction, University of Oslo, and Oslo University Hospital, Oslo, Norway
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Gong Y, Liu Y, Liu F, Wang S, Jin H, Guo F, Xu L. Ghrelin fibers from lateral hypothalamus project to nucleus tractus solitaries and are involved in gastric motility regulation in cisplatin-treated rats. Brain Res 2017; 1659:29-40. [PMID: 28093190 DOI: 10.1016/j.brainres.2017.01.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 12/28/2016] [Accepted: 01/01/2017] [Indexed: 12/16/2022]
Abstract
Ghrelin can alleviate cancer chemotherapy-induced dyspepsia in rodents, though the neural mechanisms involved are not known. Therefore, ghrelin projections from the lateral hypothalamus (LH) and its involvement in the regulation of gastric motility in cisplatin-treated rats were investigated with a multi-disciplined approach. Retrograde tracing combined with fluoro-immunohistochemical staining were used to investigate ghrelin fiber projections arising from LH and projecting to nucleus tractus solitaries (NTS). Results revealed that ghrelin fibers originating in LH project to NTS. Expression of ghrelin and its receptor growth hormone secretagogue receptor (GHS-R1a) in LH and NTS were detected by Western Blot. 2days after cisplatin dosing, expression of ghrelin in LH decreased while GHS-R1a in both LH and NTS increased. In electrophysiological experiments, the effects of N-methyl-d-aspartate (NMDA) microinjection in LH on neuronal discharge of gastric distension-responsive neurons in NTS and gastric motility were assessed. NMDA in LH excited most of ghrelin-responsive gastric distension (GD)-sensitive neurons in NTS and promoted gastric motility. This effect was partially blocked by ghrelin antibody in NTS. Furthermore, the excitatory effects of NMDA in cisplatin-treated rats were weaker than those in saline-treated rats. Behaviorally, cisplatin induced a significant increase of kaolin consumption and decrease of food intake. These studies reveal a decreased expression of ghrelin in LH and up-regulation of GHS-R1a in LH and NTS, which are involved in the regulation of GD neuronal discharge in NTS and gastric motility.
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Affiliation(s)
- Yanling Gong
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong, China.
| | - Yang Liu
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong, China
| | - Fei Liu
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong, China
| | - Shasha Wang
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong, China
| | - Hong Jin
- Department of Pharmacy, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao, Shandong, China
| | - Feifei Guo
- Department of Pathophysiology, Medical College of Qingdao University, Qingdao, Shandong, China
| | - Luo Xu
- Department of Pathophysiology, Medical College of Qingdao University, Qingdao, Shandong, China.
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Interoceptive modulation of neuroendocrine, emotional, and hypophagic responses to stress. Physiol Behav 2017; 176:195-206. [PMID: 28095318 DOI: 10.1016/j.physbeh.2017.01.027] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Revised: 01/11/2017] [Accepted: 01/13/2017] [Indexed: 11/21/2022]
Abstract
Periods of caloric deficit substantially attenuate many centrally mediated responses to acute stress, including neural drive to the hypothalamic-pituitary-adrenal (HPA) axis, anxiety-like behavior, and stress-induced suppression of food intake (i.e., stress hypophagia). It is posited that this stress response plasticity supports food foraging and promotes intake during periods of negative energy balance, even in the face of other internal or external threats, thereby increasing the likelihood that energy stores are repleted. The mechanisms by which caloric deficit alters central stress responses, however, remain unclear. The caudal brainstem contains two distinct populations of stress-recruited neurons [i.e., noradrenergic neurons of the A2 cell group that co-express prolactin-releasing peptide (PrRP+ A2 neurons), and glucagon-like peptide 1 (GLP-1) neurons] that also are responsive to interoceptive feedback about feeding and metabolic status. A2/PrRP and GLP-1 neurons have been implicated anatomically and functionally in the central control of the HPA axis, anxiety-like behavior, and stress hypophagia. The current review summarizes a growing body of evidence that caloric deficits attenuate physiological and behavioral responses to acute stress as a consequence of reduced recruitment of PrRP+ A2 and hindbrain GLP-1 neurons, accompanied by reduced signaling to their brainstem, hypothalamic, and limbic forebrain targets.
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Bülbül M, Sinen O, Gemici B, İzgüt-Uysal VN. Opposite effects of central oxytocin and arginine vasopressin on changes in gastric motor function induced by chronic stress. Peptides 2017; 87:1-11. [PMID: 27829122 DOI: 10.1016/j.peptides.2016.11.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Revised: 10/26/2016] [Accepted: 11/01/2016] [Indexed: 01/24/2023]
Abstract
Hypothalamic oxytocin (OXT) and arginine vasopressin (AVP) are known to act oppositely on hypothalamic-pituitary-adrenal (HPA) axis, stress response and gastrointestinal (GI) motility. In rodents, exposure to restraint stress (RS) delays gastric emptying (GE), however, repeated exposure to the same stressor (chronic homotypic stress (CHS)), the delayed GE is restored to basal level, while hypothalamic OXT is upregulated. In contrast, when rats are exposed to chronic heterotypic stress (CHeS), these adaptive changes are not observed. Although the involvement of central OXT in gastric motor adaptation is partly investigated, the role of hypothalamic AVP in CHeS-induced maladaptive paradigm is poorly understood. Using in-vivo brain microdialysis in rats, the changes OXT and AVP release from hypothalamus were monitored under basal non-stressed (NS) conditions and in rats exposed to acute stress (AS), CHS and CHeS. To investigate the involvement of central endogenous OXT or AVP in CHS-induced habituation and CHeS-induced maladaptation, chronic central administration of selective OXT receptor antagonist L-371257 and selective AVP V1b receptor antagonist SSR-149415 was performed daily. OXT was measured higher in AS and CHS group, but not in CHeS-loaded rats, whereas AVP significantly increased in rats exposed to AS and CHeS. Additionally, the response of the hypothalamic OXT- and AVP-producing cells was amplified following CHS and CHeS, respectively. In rats exposed to AS for 90min solid GE significantly delayed. The delayed-GE was completely restored to the basal level following CHS, however, it remained delayed in CHeS-loaded rats. The CHS-induced restoration was prevented by L-371257, whereas SSR-149415 abolished the CHeS-induced impaired GE. A significant correlation was observed between GE and (i) OXT in CHS-loaded rats (rho=0.61, p<0.05, positively), (ii) AVP in CHeS-loaded rats (rho=0.69, p<0.05, negatively). Under long term stressed conditions, the release of AVP and OXT from hypothalamus may vary depending on the content of the stressors. Central AVP appears to act oppositely to OXT by mediating CHeS-induced gastric motor maladaptation. Long term central AVP antagonism might be a pharmacological approach for the treatment of stress-related gastric motility disorders.
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Affiliation(s)
- Mehmet Bülbül
- Akdeniz University, Faculty of Medicine, Department of Physiology, Antalya, Turkey.
| | - Osman Sinen
- Akdeniz University, Faculty of Medicine, Department of Physiology, Antalya, Turkey
| | - Burcu Gemici
- Yeditepe University, Faculty of Medicine, Department of Physiology, İstanbul, Turkey
| | - V Nimet İzgüt-Uysal
- Akdeniz University, Faculty of Medicine, Department of Physiology, Antalya, Turkey
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Abstract
A large body of research has been dedicated to the effects of gastrointestinal peptides on vagal afferent fibres, yet multiple lines of evidence indicate that gastrointestinal peptides also modulate brainstem vagal neurocircuitry, and that this modulation has a fundamental role in the physiology and pathophysiology of the upper gastrointestinal tract. In fact, brainstem vagovagal neurocircuits comprise highly plastic neurons and synapses connecting afferent vagal fibres, second order neurons of the nucleus tractus solitarius (NTS), and efferent fibres originating in the dorsal motor nucleus of the vagus (DMV). Neuronal communication between the NTS and DMV is regulated by the presence of a variety of inputs, both from within the brainstem itself as well as from higher centres, which utilize an array of neurotransmitters and neuromodulators. Because of the circumventricular nature of these brainstem areas, circulating hormones can also modulate the vagal output to the upper gastrointestinal tract. This Review summarizes the organization and function of vagovagal reflex control of the upper gastrointestinal tract, presents data on the plasticity within these neurocircuits after stress, and discusses the gastrointestinal dysfunctions observed in Parkinson disease as examples of physiological adjustment and maladaptation of these reflexes.
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Jameson H, Bateman R, Byrne P, Dyavanapalli J, Wang X, Jain V, Mendelowitz D. Oxytocin neuron activation prevents hypertension that occurs with chronic intermittent hypoxia/hypercapnia in rats. Am J Physiol Heart Circ Physiol 2016; 310:H1549-57. [PMID: 27016581 DOI: 10.1152/ajpheart.00808.2015] [Citation(s) in RCA: 52] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 03/18/2016] [Indexed: 12/29/2022]
Abstract
Hypertension is a common outcome associated with obstructive sleep apnea (OSA), a prevalent yet poorly treated cardiovascular disease. Recent studies showed oxytocin (OXT), released from hypothalamic paraventricular nucleus (PVN) neurons, activates cardiac vagal neurons in the dorsal motor nucleus of the vagus (DMNX) and may blunt cardiovascular responses to stress. This study tests whether the release of OXT from PVN fibers in the DMNX is diminished with chronic intermittent hypoxia-hypercapnia (CIH/H) exposure, an animal model of OSA, and whether activation of PVN OXT neurons restores OXT release in the DMNX and prevents the hypertension resulting from CIH/H. To assess OXT release from PVN fibers, Chinese hamster ovarian (CHO) cells were engineered to be highly sensitive to OXT by stable expression of the human recombinant OXT receptor and the calcium indicator R-GECO1. PVN fibers in the DMNX were selectively photoactivated in vitro by expression of channelrhodopsin. The release of OXT onto CHO cells in the DMNX was blunted in rats exposed to 21 days of CIH/H. Chronic activation of PVN OXT neurons in vivo, using designer receptors exclusively activated by designer drugs, restored the release of OXT onto CHO cells in the DMNX. Chronic PVN OXT neuron activation in vivo also prevented the hypertension that occurred in conscious unrestrained telemetry-equipped sham rats exposed to 3 wk of CIH/H. These results demonstrate that chronic activation of OXT neurons restores the release of OXT from PVN fibers in the DMNX and prevents the hypertension that occurs with 3 wk of CIH/H exposure.
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Affiliation(s)
- Heather Jameson
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC; Institute for Biomedical Sciences, The George Washington University, Washington, DC
| | - Ryan Bateman
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC
| | - Peter Byrne
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC
| | - Jhansi Dyavanapalli
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC
| | - Xin Wang
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC; Institute for Biomedical Sciences, The George Washington University, Washington, DC
| | - Vivek Jain
- Department of Medicine, The George Washington University, Washington, DC
| | - David Mendelowitz
- Department of Pharmacology and Physiology, The George Washington University, Washington, DC; Institute for Biomedical Sciences, The George Washington University, Washington, DC;
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Chaskiel L, Paul F, Gerstberger R, Hübschle T, Konsman JP. Brainstem metabotropic glutamate receptors reduce food intake and activate dorsal pontine and medullar structures after peripheral bacterial lipopolysaccharide administration. Neuropharmacology 2016; 107:146-159. [PMID: 27016016 DOI: 10.1016/j.neuropharm.2016.03.030] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 03/18/2016] [Accepted: 03/21/2016] [Indexed: 12/20/2022]
Abstract
During infection-induced inflammation food intake is reduced. Vagal and brainstem pathways are important both in feeding regulation and immune-to-brain communication. Glutamate is released by vagal afferent terminals in the nucleus of the solitary tract and by its neurons projecting to the parabrachial nuclei. We therefore studied the role of brainstem glutamate receptors in spontaneous food intake of healthy animals and during sickness-associated hypophagia after peripheral administration of bacterial lipopolysaccharides or interleukin-1beta. Brainstem group I and II metabotropic, but not ionotropic, glutamate receptor antagonism increased food intake both in saline- and lipopolysaccharide-treated rats. In these animals, expression of the cellular activation marker c-Fos in the lateral parabrachial nuclei and lipopolysaccharide-induced activation of the nucleus of the solitary tract rostral to the area postrema were suppressed. Group I metabotropic glutamate receptors did not colocalize with c-Fos or neurons regulating gastric function in these structures. Group I metabotropic glutamate receptors were, however, found on raphé magnus neurons that were part of the brainstem circuit innervating the stomach and on trigeminal and hypoglossal motor neurons. In conclusion, our findings show that brainstem metabotropic glutamate receptors reduce food intake and activate the lateral parabrachial nuclei as well as the rostral nucleus of the solitary tract after peripheral bacterial lipopolysaccharide administration. They also provide insight into potential group I metabotropic glutamate receptor-dependent brainstem circuits mediating these effects.
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Affiliation(s)
- Léa Chaskiel
- CNRS, PsychoNeuroImmunologie, Nutrition et Génétique, UMR 5226, Bordeaux, France; Univ. Bordeaux, PsyNuGen, UMR 5226, Bordeaux, France
| | - Flora Paul
- CNRS, PsychoNeuroImmunologie, Nutrition et Génétique, UMR 5226, Bordeaux, France; Univ. Bordeaux, PsyNuGen, UMR 5226, Bordeaux, France
| | - Rüdiger Gerstberger
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, 35392 Giessen, Germany
| | - Thomas Hübschle
- Institut für Veterinär-Physiologie und -Biochemie, Justus-Liebig-Universität Giessen, 35392 Giessen, Germany
| | - Jan Pieter Konsman
- CNRS, PsychoNeuroImmunologie, Nutrition et Génétique, UMR 5226, Bordeaux, France; Univ. Bordeaux, PsyNuGen, UMR 5226, Bordeaux, France.
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Arginine Vasopressin Injected into the Dorsal Motor Nucleus of the Vagus Inhibits Gastric Motility in Rats. Gastroenterol Res Pract 2015; 2016:4618672. [PMID: 26843857 PMCID: PMC4710933 DOI: 10.1155/2016/4618672] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Revised: 10/25/2015] [Accepted: 10/27/2015] [Indexed: 12/14/2022] Open
Abstract
Background. Until now, the effect of arginine vasopressin (AVP) in the DMV on gastric motility and the possible modulating pathway between the DMV and the gastrointestinal system remain poorly understood. Objectives. We aimed to explore the role of AVP in the DMV in regulating gastric motility and the possible central and peripheral pathways. Material and Methods. Firstly, we microinjected different doses of AVP into the DMV and investigated its effects on gastric motility in rats. Then, the possible central and peripheral pathways that regulate gastric motility were also discussed by microinjecting SR49059 (a specific AVP receptor antagonist) into the DMV and intravenous injection of hexamethonium (a specific neuronal nicotinic cholinergic receptor antagonist) before AVP microinjection. Results. Following microinjection of AVP (180 pmol and 18 pmol) into the DMV, the gastric motility (including total amplitude, total duration, and motility index of gastric contraction) was significantly inhibited (P < 0.05). Moreover, the inhibitory effect of AVP (180 pmol) on gastric motility could be blocked completely by both SR49059 (320 pmol) and hexamethonium (8 μmol). Conclusions. It is concluded that AVP inhibits the gastric motility by acting on the specific AVP receptor in the DMV, with the potential involvement of the parasympathetic preganglionic cholinergic fibers.
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David RB, Roncari CF, Lauar MR, Vendramini RC, Antunes-Rodrigues J, Menani JV, De Luca LA. Sodium intake, brain c-Fos protein and gastric emptying in cell-dehydrated rats treated with methysergide into the lateral parabrachial nucleus. Physiol Behav 2015; 151:111-20. [DOI: 10.1016/j.physbeh.2015.07.014] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Revised: 06/11/2015] [Accepted: 07/10/2015] [Indexed: 10/23/2022]
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Elson AE, Simerly RB. Developmental specification of metabolic circuitry. Front Neuroendocrinol 2015; 39:38-51. [PMID: 26407637 PMCID: PMC4681622 DOI: 10.1016/j.yfrne.2015.09.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Revised: 09/18/2015] [Accepted: 09/21/2015] [Indexed: 01/16/2023]
Abstract
The hypothalamus contains a core circuitry that communicates with the brainstem and spinal cord to regulate energy balance. Because metabolic phenotype is influenced by environmental variables during perinatal development, it is important to understand how these neural pathways form in order to identify key signaling pathways that are responsible for metabolic programming. Recent progress in defining gene expression events that direct early patterning and cellular specification of the hypothalamus, as well as advances in our understanding of hormonal control of central neuroendocrine pathways, suggest several key regulatory nodes that may represent targets for metabolic programming of brain structure and function. This review focuses on components of central circuitry known to regulate various aspects of energy balance and summarizes what is known about their developmental neurobiology within the context of metabolic programming.
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Affiliation(s)
- Amanda E Elson
- The Saban Research Institute, Children's Hospital Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, CA 90027, USA
| | - Richard B Simerly
- The Saban Research Institute, Children's Hospital Los Angeles, University of Southern California, Keck School of Medicine, Los Angeles, CA 90027, USA.
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37
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Browning KN, Travagli RA. Central nervous system control of gastrointestinal motility and secretion and modulation of gastrointestinal functions. Compr Physiol 2015; 4:1339-68. [PMID: 25428846 DOI: 10.1002/cphy.c130055] [Citation(s) in RCA: 331] [Impact Index Per Article: 36.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Although the gastrointestinal (GI) tract possesses intrinsic neural plexuses that allow a significant degree of autonomy over GI functions, the central nervous system (CNS) provides extrinsic neural inputs that regulate, modulate, and control these functions. While the intestines are capable of functioning in the absence of extrinsic inputs, the stomach and esophagus are much more dependent upon extrinsic neural inputs, particularly from parasympathetic and sympathetic pathways. The sympathetic nervous system exerts a predominantly inhibitory effect upon GI muscle and provides a tonic inhibitory influence over mucosal secretion while, at the same time, regulates GI blood flow via neurally mediated vasoconstriction. The parasympathetic nervous system, in contrast, exerts both excitatory and inhibitory control over gastric and intestinal tone and motility. Although GI functions are controlled by the autonomic nervous system and occur, by and large, independently of conscious perception, it is clear that the higher CNS centers influence homeostatic control as well as cognitive and behavioral functions. This review will describe the basic neural circuitry of extrinsic inputs to the GI tract as well as the major CNS nuclei that innervate and modulate the activity of these pathways. The role of CNS-centered reflexes in the regulation of GI functions will be discussed as will modulation of these reflexes under both physiological and pathophysiological conditions. Finally, future directions within the field will be discussed in terms of important questions that remain to be resolved and advances in technology that may help provide these answers.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, Pennsylvania
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Bhagat R, Fortna SR, Browning KN. Exposure to a high fat diet during the perinatal period alters vagal motoneurone excitability, even in the absence of obesity. J Physiol 2014; 593:285-303. [PMID: 25556801 DOI: 10.1113/jphysiol.2014.282806] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2014] [Accepted: 10/24/2014] [Indexed: 01/02/2023] Open
Abstract
KEY POINTS Obesity is recognized as being multifactorial in origin, involving both genetic and environmental factors. The perinatal period is known to be critically important in the development of neural circuits responsible for energy homeostasis and the integration of autonomic reflexes. Diet-induced obesity alters the biophysical, pharmacological and morphological properties of vagal neurocircuits regulating upper gastrointestinal tract functions, including satiety. Less information is available, however, regarding the effects of a high fat diet (HFD) itself on the properties of vagal neurocircuits. The present study was designed to test the hypothesis that exposure to a HFD during the perinatal period alters the electrophysiological, pharmacological and morphological properties of vagal efferent motoneurones innervating the stomach. Our data indicate that perinatal HFD decreases the excitability of gastric-projecting dorsal motor nucleus neurones and dysregulates neurotransmitter release from synaptic inputs and that these alterations occur prior to the development of obesity. These findings represent the first direct evidence that exposure to a HFD modulates the processing of central vagal neurocircuits even in the absence of obesity. The perinatal period is critically important to the development of autonomic neural circuits responsible for energy homeostasis. Vagal neurocircuits are vital to the regulation of upper gastrointestinal functions, including satiety. Diet-induced obesity modulates the excitability and responsiveness of both peripheral vagal afferents and central vagal efferents but less information is available regarding the effects of diet per se on vagal neurocircuit functions. The aims of this study were to investigate whether perinatal exposure to a high fat diet (HFD) dysregulated dorsal motor nucleus of the vagus (DMV) neurones, prior to the development of obesity. Whole cell patch clamp recordings were made from gastric-projecting DMV neurones in thin brainstem slices from rats that were exposed to either a control diet or HFD from pregnancy day 13. Our data demonstrate that following perinatal HFD: (i) DMV neurones had decreased excitability and input resistance with a reduced ability to fire action potentials; (ii) the proportion of DMV neurones excited by cholecystokinin (CCK) was unaltered but the proportion of neurones in which CCK increased excitatory glutamatergic synaptic inputs was reduced; (iii) the tonic activation of presynaptic group II metabotropic glutamate receptors on inhibitory nerve terminals was attenuated, allowing modulation of GABAergic synaptic transmission; and (iv) the size and dendritic arborization of gastric-projecting DMV neurones was increased. These results suggest that perinatal HFD exposure compromises the excitability and responsiveness of gastric-projecting DMV neurones, even in the absence of obesity, suggesting that attenuation of vago-vagal reflex signalling may precede the development of obesity.
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Affiliation(s)
- Ruchi Bhagat
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, Hershey, PA 17033, USA
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39
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Babic T, Ambler J, Browning KN, Travagli RA. Characterization of synapses in the rat subnucleus centralis of the nucleus tractus solitarius. J Neurophysiol 2014; 113:466-74. [PMID: 25355962 DOI: 10.1152/jn.00598.2014] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The nucleus tractus solitarius (NTS) receives subdiaphragmatic visceral sensory information via vagal A- or C-fibers. We have recently shown that, in contrast to cardiovascular NTS medialis neurons, which respond to either purinergic or vanilloid agonists, the majority of esophageal NTS centralis (cNTS) neurons respond to vanilloid agonists, whereas a smaller subset responds to both vanilloid and purinerigic agonists. The present study aimed to further investigate the neurochemical and synaptic characteristics of cNTS neurons using whole cell patch-clamp, single cell RT-PCR and immunohistochemistry. Excitatory postsynaptic currents (EPSCs) were evoked in cNTS by tractus solitarius stimulation, and in 19 of 64 neurons perfusion with the purinergic agonist αβ-methylene ATP (αβMeATP) increased the evoked EPSC amplitude significantly. Furthermore, neurons with αβMeATP-responsive synaptic inputs had different probabilities of release compared with nonresponsive neurons. Single cell RT-PCR revealed that 8 of 13 αβMeATP-responsive neurons expressed metabotropic glutamate receptor 8 (mGluR8) mRNA, which our previous studies have suggested is a marker of glutamatergic neurons, whereas only 3 of 13 expressed glutamic acid dehydroxylase, a marker of GABAergic neurons. A significantly lower proportion of αβMeATP-nonresponsive neurons expressed mGluR8 (2 of 30 neurons), whereas a greater proportion expressed glutamic acid dehydroxylase (12 of 30 neurons). Esophageal distension significantly increased the number of colocalized mGluR8- and c-Fos-immunoreactive neurons in the cNTS from 8.0 ± 4% to 20 ± 2.5%. These data indicate that cNTS comprises distinct neuronal subpopulations that can be distinguished based on their responses to purinergic agonists and that these subpopulations have distinct neurochemical and synaptic characteristics, suggesting that integration of sensory inputs from the esophagus relies on a discrete organization of synapses between vagal afferent fibers and cNTS neurons.
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Affiliation(s)
- Tanja Babic
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania
| | - Jason Ambler
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania
| | - Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania
| | - R Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, Pennsylvania
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Browning KN, Babic T, Toti L, Holmes GM, Coleman FH, Travagli RA. Plasticity in the brainstem vagal circuits controlling gastric motor function triggered by corticotropin releasing factor. J Physiol 2014; 592:4591-605. [PMID: 25128570 DOI: 10.1113/jphysiol.2014.278192] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Stress impairs gastric emptying, reduces stomach compliance and induces early satiety via vagal actions. We have shown recently that the ability of the anti-stress neuropeptide oxytocin (OXT) to modulate vagal brainstem circuits undergoes short-term plasticity via alterations in cAMP levels subsequent to vagal afferent fibre-dependent activation of metabotropic glutamate receptors. The aim of the present study was to test the hypothesis that the OXT-induced gastric response undergoes plastic changes in the presence of the prototypical stress hormone, corticotropin releasing factor (CRF). Whole cell patch clamp recordings showed that CRF increased inhibitory GABAergic synaptic transmission to identified corpus-projecting dorsal motor nucleus of the vagus (DMV) neurones. In naive brainstem slices, OXT perfusion had no effect on inhibitory synaptic transmission; following exposure to CRF (and recovery from its actions), however, re-application of OXT inhibited GABAergic transmission in the majority of neurones tested. This uncovering of the OXT response was antagonized by pretreatment with protein kinase A or adenylate cyclase inhibitors, H89 and di-deoxyadenosine, respectively, indicating a cAMP-mediated mechanism. In naive animals, OXT microinjection in the dorsal vagal complex induced a NO-mediated corpus relaxation. Following CRF pretreatment, however, microinjection of OXT attenuated or, at times reversed, the gastric relaxation which was insensitive to l-NAME but was antagonized by pretreatment with a VIP antagonist. Immunohistochemical analyses of vagal motoneurones showed an increased number of oxytocin receptors present on GABAergic terminals of CRF-treated or stressed vs. naive rats. These results indicate that CRF alters vagal inhibitory circuits that uncover the ability of OXT to modulate GABAergic currents and modifies the gastric corpus motility response to OXT.
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Affiliation(s)
- Kirsteen N Browning
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Tanja Babic
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Luca Toti
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - Gregory M Holmes
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - F Holly Coleman
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
| | - R Alberto Travagli
- Department of Neural and Behavioral Sciences, Penn State University College of Medicine, Hershey, PA, 17033, USA
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Babic T, Travagli RA. Role of metabotropic glutamate receptors in the regulation of pancreatic functions. Biochem Pharmacol 2013; 87:535-42. [PMID: 24355565 DOI: 10.1016/j.bcp.2013.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2013] [Revised: 12/05/2013] [Accepted: 12/05/2013] [Indexed: 01/03/2023]
Abstract
The pancreas consists of two major divisions, the exocrine and the endocrine pancreas. Recent data from our laboratory have shown that the functions of the two divisions are under modulatory regulation by separate neurocircuits that originate in the dorsal motor nucleus of the vagus (DMV). Metabotropic glutamate receptors (mGluRs) are expressed throughout the central nervous system and have been implicated in the modulation of synaptic transmission. mGluRs consist of three groups of receptors, which can be distinguished based on their pharmacological properties and second messenger systems. Group I mGluRs predominantly increase, whereas group II and III mGluRs decrease synaptic transmission. Group II and group III mGluRs are present on excitatory and inhibitory synaptic terminals impinging on pancreas-projecting DMV neurons. We have shown that group II mGluRs regulate both exocrine pancreatic secretions and insulin release, whereas group III mGluRs only regulate insulin release. Several mGluR agonists and antagonists have been shown to have clinical uses for disorders accompanied by abnormal synaptic transmission, including anxiety and Parkinson's disease. Moreover, a negative allosteric modulator of Group I mGluRs is effective in alleviating symptoms of gastro-esophageal reflux disease (GERD). Since the role of the three mGluR groups in mediating different gastrointestinal (GI) functions appears to be highly specific, the use of agonists or antagonists directed at a single receptor group could potentially provide highly selective targets for the treatment of GI disorders including GERD, functional dyspepsia and acute pancreatitis.
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Affiliation(s)
- Tanja Babic
- Neural and Behavioral Sciences Penn State College of Medicine, Department of Neural and Behavioral Sciences, 500 University Drive-MC H109 Hershey, PA 17033-0850, USA.
| | - R Alberto Travagli
- Neural and Behavioral Sciences Penn State College of Medicine, Department of Neural and Behavioral Sciences, 500 University Drive-MC H109 Hershey, PA 17033-0850, USA
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Ott V, Finlayson G, Lehnert H, Heitmann B, Heinrichs M, Born J, Hallschmid M. Oxytocin reduces reward-driven food intake in humans. Diabetes 2013; 62:3418-25. [PMID: 23835346 PMCID: PMC3781467 DOI: 10.2337/db13-0663] [Citation(s) in RCA: 172] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Experiments in animals suggest that the neuropeptide oxytocin acts as an anorexigenic signal in the central nervous control of food intake. In humans, however, research has almost exclusively focused on the involvement of oxytocin in the regulation of social behavior. We investigated the effect of intranasal oxytocin on ingestion and metabolic function in healthy men. Food intake in the fasted state was examined 45 min after neuropeptide administration, followed by the assessment of olfaction and reward-driven snack intake in the absence of hunger. Energy expenditure was registered by indirect calorimetry, and blood was repeatedly sampled to determine concentrations of blood glucose and hormones. Oxytocin markedly reduced snack consumption, restraining, in particular, the intake of chocolate cookies by 25%. Oxytocin, moreover, attenuated basal and postprandial levels of adrenocorticotropic hormone and cortisol and curbed the meal-related rise in plasma glucose. Energy expenditure and hunger-driven food intake as well as olfactory function were not affected. Our results indicate that oxytocin, beyond its role in social bonding, regulates nonhomeostatic, reward-related energy intake, hypothalamic-pituitary-adrenal axis activity, and the glucoregulatory response to food intake in humans. These effects can be assumed to converge with the psychosocial function of oxytocin and imply possible applications in the treatment of metabolic disorders.
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Affiliation(s)
- Volker Ott
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
| | - Graham Finlayson
- Institute of Psychological Sciences, University of Leeds, Leeds, U.K
| | - Hendrik Lehnert
- Department of Internal Medicine I, University of Lübeck, Lübeck, Germany
| | - Birte Heitmann
- Department of Neuroendocrinology, University of Lübeck, Lübeck, Germany
| | - Markus Heinrichs
- Laboratory for Biological and Personality Psychology, Department of Psychology, University of Freiburg, Freiburg, Germany
- Freiburg Brain Imaging Center, University Medical Center, University of Freiburg, Freiburg, Germany
| | - Jan Born
- Department of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen (Paul Langerhans Institute Tübingen), Tübingen, Germany
| | - Manfred Hallschmid
- Department of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Tübingen, Germany
- Institute for Diabetes Research and Metabolic Diseases of the Helmholtz Centre Munich at the University of Tübingen (Paul Langerhans Institute Tübingen), Tübingen, Germany
- Corresponding author: Manfred Hallschmid,
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