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Taste and Food Choice
Published in Alan R. Hirsch, Nutrition and Sensation, 2023
The mechanisms underlying the development of conditioned taste aversions have been studied mainly in rats. Taste-evoked activity in the NST (Chang and Scott 1984; McCaughey, Giza, Nolan, and Scott 1997) and in the parabrachial nucleus (PBN) (Shimura, Tanaka, and Yamamoto 1997) rises to a taste that is paired with nausea. In the NST, that increase is associated with a reorganization of inputs such that the incriminated taste no longer elicits swallowing reflexes and parasympathetic activity designed to ingest and assimilate the chemical, but rather induces the opposite: rejection reflexes. In the PBN, the evoked activity shifts from a subnucleus associated with positive hedonics to one normally activated by aversive tastes (Yamamoto 1993). Discrete subnuclei of the PBN are hypothesized to send separate projections to forebrain areas that analyze taste quality and hedonics. Thus, the shift in representation of the offending taste could serve as the basis for its reversed hedonics—from appealing to disgusting—established in the brainstem but manifested in the forebrain.
Biological Activities of Peptides in Brain Tissues
Published in Gerard O’Cuinn, Metabolism of Brain Peptides, 2020
The medulla is the region of the brainstem with the largest number of immunoreactive cell bodies, at least in the rat. The nucleus of the solitary tract, nuclei raphe pallidus and obscurus, lateral reticular nucleus and spinal trigeminal nucleus have intensely-stained clusters of perikarya. GAL ir cell bodies are also detectable in the nucleus ambiguous, hypoglossal nerve and along the ventral border of the area postrema. Cell bodies in the raphes pallidus and obscurus send processes through the bulbospinal pathway to laminae I and II of the spinal cord. Fibers from neurons of the nucleus of the solitary tract ascend via the ascending noradrenergic pathways and innervate most regions of the brain. A projection from this nucleus to the parabrachial nucleus has also been reported. On the other hand, the nucleus of the solitary tract receives projections from the paraventricular, dorsomedial, preoptic and dorsomedial nuclei of the hypothalamus127. GAL is co-localized with acetylcholine and CGRP in motoneurons of cranial nerves that innervate striated muscle fibers.
Brainstem and Cardiovascular Regulation
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
Ching-Jiunn Tseng, Che-Se Tung
There are other nuclei in the brainstem that play an important role in central cardiovascular control. The dorsal medulla, parabrachial nucleus and locus coeruleus are all involved in the complex central cardiovascular control. There are interconnections and projections among these nuclei, and usually the interconnections and projections are bilateral and reciprocal.
The pleiotropic of GLP-1/GLP-1R axis in central nervous system diseases
Published in International Journal of Neuroscience, 2023
LongQing Zhang, Wen Zhang, XueBi Tian
Although, activation of GLP-1R could improve multiple CNS diseases, we still need focus on the adverse effects induced by GLP-1R agonists such as, nausea and vomiting and so on [183, 184]. A study has proved that ablation of area postrema GLP-1R neurons in mice eliminated Ex4 evoked aversion through the single-nucleus RNA sequencing and mouse genetic tools for cell-specific manipulation [185]. Moreover, it was also found that the parabrachial nucleus (PBN) critically contributed to the hypophagic effects of systemically delivered Ex4 by enhancing visceral feedback [186]. In addition, GLP-1R agonists also affected water and salt metabolism, a study showed that Ex4 and liraglutide both suppressed angiotensin II (AngII) -induced water intake; however, only Ex4 suppressed saline intake [187]. In clinical, slightly greater severity of nausea and gastrointestinal side effects induced by oral GLP-1R agonists may reduce patient compliance; so, it was necessary to develop new GLP-1R agonists without these adverse effects, such as non-peptidic GLP-1R agonists [183].
Genetic identification of preoptic neurons that regulate body temperature in mice
Published in Temperature, 2022
Natalia L. S. Machado, Clifford B. Saper
Previous studies suggested that the lateral parabrachial nucleus relays cold-sensitive signals from dorsal root ganglion cells to the MnPO [42]. However, the circuits that regulate cold-defense responses were not further elucidated. Recently, Pinol and colleagues reported that the bombesin-like receptor 3 (BRS3) is expressed by MnPO neurons that are activated by cold exposure [43]. Opto- or chemogenetic activation of the MnPO-BR3 neurons caused brown adipose thermogenesis (but not tail vasoconstriction) with a subsequent elevation of Tb. Using optogenetic stimulation of MnPO-BRS3 terminal fields demonstrated elevation of Tb during stimulation of terminals in the DMH, paraventricular nucleus of the hypothalamus (PVH), and the periaqueductal gray matter (PAG), although these could have been collaterals of the same descending projection. After silencing the BRS3-expressing MnPO neurons using a viral vector that allowed genetically directed expression of tetanus toxin, mice had no change in baseline Tb or its circadian rhythm. However, the animals showed an exacerbated reduction of Tb in response to food deprivation during torpor and disrupted Tb regulation during both cold or warm challenge [4445].
Emerging evidence for noninvasive vagus nerve stimulation for the treatment of vestibular migraine
Published in Expert Review of Neurotherapeutics, 2020
Vagal afferents and efferents terminate in four medullary vagal nuclei: the nucleus tractus solitarius (NTS), nucleus ambiguus, trigeminal spinal nucleus, and dorsal motor vagus nucleus (DMX) [8]. The NTS is the first major relay station for vagal afferents, contains trigemino-vestibulo-vagal neurocircuitry, and plays an important role in motion sickness and migraine-related nausea [11–13]. It receives afferents from the ipsilateral medial vestibular nucleus (via the lateral pathway), the ipsilateral nucleus prepositus hypoglossi (via the medial pathway), and bilateral inferior vestibular nuclei [8]. The NTS receives vestibulo-cerebellar and vestibulo-hypothalamic afferents via the parabrachial and Kolliker-Fuse nuclei [14,15]. Indicating a role in migraine, neurons connecting the parabrachial nucleus and NTS express calcitonin gene-related peptide [16,17], and play a major role in conditioned taste aversion (the animal model for motion sickness) [18]. The DMX receives vestibular afferents [19,20], and projects to the cerebellar vermis, fastigial nucleus, and nucleus interpositus [21], structures that are important in ocular motor control [22]; these connections suggest a pathway by which nVNS modulates VM-associated vertigo and nystagmus. Other brainstem nuclei that host vestibulo-vagal connections, and thus provide a possible substrate for nVNS to act on VM episodes include the rostro-ventro-lateral medulla, reticular formation, locus coeruleus, and nucleus intercalatus [8,19,20].