Stimulation of the nucleus raphe obscurus produces marked serotonin release into the dorsal medulla of fed but not fasted rats — glutamatergic dependence

Mohammed, Jeanette R.; Saska, Teresa A.; Chi, J.; Stephens, Robert L.

doi:10.1016/0006-8993(95)00505-k

Cited by 16 publications

(5 citation statements)

References 15 publications

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“…This suggests that the basal tone of serotonin might originate from the raphe obscurus, which lies ventral to the NTS, is present in the coronal, but not the horizontal slice, and is an endogenous source of 5-HT producing neurons located ventral to the NTS (41). Interestingly, stimulation of the raphe obscurus produces significant 5-HT release into the dorsal vagal complex (DVC; i.e., the NTS and dorsal motor nucleus of the vagus), in fed, but not fasted rats (37,65). In addition, high-fat diet blunts the ability of glucose to increase 5-HT 3 R responses (62).…”

Section: Discussionmentioning

confidence: 99%

High glucose increases action potential firing of catecholamine neurons in the nucleus of the solitary tract by increasing spontaneous glutamate inputs

Roberts

Zhu

Zhao

et al. 2017

American Journal of Physiology-Regulatory, Integrative and Comp

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Glucose is a crucial substrate essential for cell survival and function. Changes in glucose levels impact neuronal activity and glucose deprivation increases feeding. Several brain regions have been shown to respond to glucoprivation, including the nucleus of the solitary tract (NTS) in the brain stem. The NTS is the primary site in the brain that receives visceral afferent information from the gastrointestinal tract. The catecholaminergic (CA) subpopulation within the NTS modulates many homeostatic functions including cardiovascular reflexes, respiration, food intake, arousal, and stress. However, it is not known if they respond to changes in glucose. Here we determined whether NTS-CA neurons respond to changes in glucose concentration and the mechanism involved. We found that decreasing glucose concentrations from 5 mM to 2 mM to 1 mM, significantly decreased action potential firing in a cell-attached preparation, whereas increasing it back to 5 mM increased the firing rate. This effect was dependent on glutamate release from afferent terminals and required presynaptic 5-HTRs. Decreasing the glucose concentration also decreased both basal and 5-HTR agonist-induced increase in the frequency of spontaneous glutamate inputs onto NTS-CA neurons. Low glucose also blunted 5-HT-induced inward currents in nodose ganglia neurons, which are the cell bodies of vagal afferents. The effect of low glucose in both nodose ganglia cells and in NTS slices was mimicked by the glucokinase inhibitor glucosamine. This study suggests that NTS-CA neurons are glucosensing through a presynaptic mechanism that is dependent on vagal glutamate release, 5-HTR activity, and glucokinase.

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Section: Discussionmentioning

confidence: 99%

High glucose increases action potential firing of catecholamine neurons in the nucleus of the solitary tract by increasing spontaneous glutamate inputs

Roberts

Zhu

Zhao

et al. 2017

American Journal of Physiology-Regulatory, Integrative and Comp

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“…Factors related to food intake behaviour may also influence the excitability of neurones in NRO. NRO-evoked release of 5-HT in the dorsomedial medulla (in the region containing abdominal vagal neurones) was depressed in fasted rats compared with animals that had been freely fed (Mohammed et al 1995). On the other hand, peripheral administration of cholecystokinin, which reduces feeding and gastric motility, produced a rise in neuronal activity, reflected by increased expression of c-fos in neurones in NRO (Rinaman et al 1993 In addition to behavioural state-dependent changes in excitability, there is evidence for a degree of chemical specificity between functional groups of raphe neurones.…”

Section: Gastrointestinal Controlmentioning

confidence: 93%

Section: Gastrointestinal Controlmentioning

confidence: 98%

“…Interestingly, there is evidence for a degree of plasticity in the excitability of this raphe-vagal projection. Raphe-evoked release of 5-HT in the dorsomedial medulla (the region containing vagal motoneurones) could be demonstrated in rats that had been freely fed but was absent in fasted animals (Mohammed, Saska, Chi & Stephens, 1995 (Willis, 1982 (Oliveras et al 1975). Acute studies in anaesthetized rats have shown that stimulation in NRO produces a serotonergically mediated facilitation of the excitability of lumbar motorneurones via an action at 5-HT1 receptors (Roberts, Davies, Girdlestone & Foster, 1988 (Oliveras, Montagne-Clavel & Martin, 1991;Blair & Evans, 1993).…”

Section: Gastrointestinal Controlmentioning

confidence: 99%

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The medullary raphe nuclei: a system for integration and gain control in autonomic and somatomotor responsiveness?

Lovick¹

1997

Experimental Physiology

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“…Serotonergic vagal sensory afferents from the nodose ganglia terminate in and immediately underneath the area postrema in the rat, suggesting a role for serotonergic receptors in these regions mediating gastrointestinal reflexes (27). Serotonin release is elevated in the dorsal vagal complex in fed compared to fasted rats (30). Furthermore, small increases of gastric motility can be produced by co-injections of serotonin and thyrotropin-releasing hormone into the dorsal vagal complex (31).…”

Section: Discussionmentioning

confidence: 99%

The Subnuclear Distribution of 5-HT1A Receptors in the Human Nucleus of the Solitary Tract and Selected Structures of the Caudal Medulla

Spurney

Ohuoha

Murray

et al. 2020

MJM

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The distribution of 5-HT1A receptors in the subnuclei of the human caudal nucleus of solitary tract and adjacent structures in the dorsal vagal complex was studied using [3H]8-OH-DPAT, a highly selective 5-HT1A receptor agonist. The highest binding of the labeled ligand was found in the dorsal motor nucleus of the vagus, followed by the medial, intermediate, and subpostremal subnuclei of the nucleus of solitary tract. Previous animal studies suggest an important role for these structures in the regulation of visceral function, particularly for the gastrointestinal and cardiovascular systems. The results of this study suggest the possibility of an analogous role for 5-HT1A receptors in the regulation of these autonomic pathways in humans as well.

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Stimulation of the nucleus raphe obscurus produces marked serotonin release into the dorsal medulla of fed but not fasted rats — glutamatergic dependence

Cited by 16 publications

References 15 publications

High glucose increases action potential firing of catecholamine neurons in the nucleus of the solitary tract by increasing spontaneous glutamate inputs

High glucose increases action potential firing of catecholamine neurons in the nucleus of the solitary tract by increasing spontaneous glutamate inputs

The medullary raphe nuclei: a system for integration and gain control in autonomic and somatomotor responsiveness?

The Subnuclear Distribution of 5-HT1A Receptors in the Human Nucleus of the Solitary Tract and Selected Structures of the Caudal Medulla

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