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Hypothalamus
About: Hypothalamus is a research topic. Over the lifetime, 22301 publications have been published within this topic receiving 1085925 citations.
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TL;DR: Small lesions essentially restricted to the PVN are found to produce overeating and increased body weight, in both female and male rats maintained on either lab chow pellets or high fat mash.
367 citations
TL;DR: Electrophysiological analysis indicates that VIP enhances inhibitory synaptic transmission within the SCN of wild-type and VIP/PHI-deficient mice, suggesting that VIP/ PHI peptides are critically involved in both the generation of circadian oscillations as well as the normal synchronization of these rhythms to light.
Abstract: The related neuropeptides vasoactive intestinal peptide (VIP) and peptide histidine isoleucine (PHI) are expressed at high levels in the neurons of the suprachiasmatic nucleus (SCN), but their func...
365 citations
TL;DR: The HPA stress response appears to be a product of both the physiologic importance of the stimulus and the specific pathways a given stimulus excites, and may require interaction with homeostatic information prior to promoting an HPA response.
Abstract: The hypothalamo-pituitary-adrenocortical (HPA) axis is the primary modulator of the adrenal glucocorticoid stress response. Activation of this axis occurs by way of a discrete set of neurons in the hypothalamic paraventricular nucleus (PVN). The PVN neuron appears to be affected by multiple sources, including (1) brainstem aminergic/peptidergic afferents; (2) blood-borne information; (3) indirect input from limbic system-associated regions, including the prefrontal cortex, hippocampus, and amygdala; and (4) local-circuit interactions with the preoptic-hypothalamic continuum. Analysis of the literature suggests that different classes of stressor employ different stress circuits. Severe physiologic ("systemic") stress appears to trigger brainstem/circumventricular organ systems that project directly to the paraventricular nucleus. In contrast, stressors requiring interpretation with respect to previous experience ("processive" stressors) reach the PVN by way of multisynaptic limbic pathways. Limbic regions mediating processive stress responses appear to have bisynaptic connections with the PVN, forming intervening connections with preoptic/hypothalamic GABAergic neurons. Stressors of the latter category may thus require interaction with homeostatic information prior to promoting an HPA response. The HPA stress response thus appears to be a product of both the physiologic importance of the stimulus and the specific pathways a given stimulus excites.
365 citations
TL;DR: In this article, the authors explored systematically the distribution of leptin-activated neurons throughout the rat brain and investigated the chemical identity of subsets of these leptinactivated cells, and found that leptin stimulates brain pathways containing neuropeptides that are involved in the regulation of energy balance, autonomic homeostasis, and neuroendocrine status.
Abstract: Leptin has profound effects on food intake, body weight, and neuroendocrine status. The lack of leptin results in hormonal and metabolic alterations and a dramatic increase in body weight. Leptin acts in the brain, especially in the hypothalamus; however, the central nervous system sites that respond to leptin have not been examined comprehensively. In this study, we explored systematically the distribution of leptin-activated neurons throughout the rat brain. Furthermore, we investigated the chemical identity of subsets of these leptin-activated cells. Fos-like immunoreactivity (Fos-IR) was investigated in the rat brain after two different doses of leptin (1.0 mg/kg and 5.0 mg/kg) at 2 hours and 6 hours after injections. The induction of Fos-IR was observed in hypothalamic nuclei, including the paraventricular nucleus (PVH), the retrochiasmatic area (RCA), the ventromedial nucleus (VMH), the dorsomedial nucleus (DMH), the arcuate nucleus (Arc), and the ventral premammillary nucleus (PMV). In addition, leptin-induced Fos-IR was found in several nuclei of the brainstem, including the superior lateral and external lateral subdivisions of the parabrachial nucleus (slPB and elPB, respectively), the supragenual nucleus, and the nucleus of the solitary tract (NTS). By using double-labeling immunohistochemistry or immunohistochemistry coupled with in situ hybridization, leptin-activated neurons were found that contained cocaine- and amphetamine-regulated transcript mRNA in several hypothalamic nuclei, including the RCA, Arc, DMH, and PMV. In the Arc and DMH, leptin-induced Fos-IR was observed in neurons that expressed neurotensin mRNA. Dynorphin neurons in the VMH and in the Arc also expressed Fos-IR. In the brainstem, we found that cholecystokinin neurons in the slPB and glucagon-like peptide-1 neurons in the NTS were activated by leptin. We also investigated the coexpression of Fos-IR and the long form of the leptin receptor (OBRb) mRNA. We found double-labeled neurons surrounding the median eminence and in the RCA, Arc, VMH, DMH, and PMV. However, in brainstem sites, very little OBRb mRNA was found; thus, there were very few double-labeled cells. These results suggest that leptin stimulates brain pathways containing neuropeptides that are involved in the regulation of energy balance, autonomic homeostasis, and neuroendocrine status.
362 citations
TL;DR: There are two separate populations of pre‐sympathetic and pre‐parasympathetic neurons within the paraventricular nucleus of the hypothalamus, Interestingly, this segregation persists into the SCN, where, as a result, the day‐night balance in autonomic function of the organs is affected by specialized pre‐Sympathetic or pre‐ parasympathy SCN neurons.
Abstract: Opposing parasympathetic and sympathetic signals determine the autonomic output of the brain to the body and the change in balance over the sleep-wake cycle The suprachiasmatic nucleus (SCN) organizes the activity/inactivity cycle and the behaviors that go along with it, but it is unclear how the hypothalamus, in particular the SCN, with its high daytime electrical activity, influences this differentiated autonomic balance In a first series of experiments, we visualized hypothalamic pre-sympathetic neurons by injecting the retrograde tracer Fluoro-Gold into the thoracic sympathetic nuclei of the spinal cord Pre-parasympathetic neurons were revealed by injection of the retrograde trans-synaptic tracer pseudorabies virus (PRV) into the liver and by sympathetic liver denervation, forcing the virus to infect via the vagus nerve only This approach revealed separate pre-sympathetic and pre-parasympathetic neurons in the brainstem and hypothalamus Next, selective retrograde tracing with two unique reporter PRV strains, one injected into the adrenal and the other into the sympathetic denervated liver, demonstrated that there are two separate populations of pre-sympathetic and pre-parasympathetic neurons within the paraventricular nucleus of the hypothalamus Interestingly, this segregation persists into the SCN, where, as a result, the day-night balance in autonomic function of the organs is affected by specialized pre-sympathetic or pre-parasympathetic SCN neurons These separate preautonomic SCN neurons provide the anatomical basis for the circadian-driven regulation of the parasympathetic and sympathetic autonomic output
362 citations