Hypothalamus

About: Hypothalamus is a research topic. Over the lifetime, 22301 publications have been published within this topic receiving 1085925 citations.

Corticotropin-releasing factor receptors and pituitary adrenal responses during immobilization stress

Abstract: The regulation of pituitary and brain CRF receptors and corticotroph responses during stress were studied in rats subjected to prolonged immobilization. Plasma ACTH levels showed the characteristic biphasic changes, with a rapid 23-fold increase in 15 min, followed by a decrease to about twice the basal levels after 6-h immobilization. In contrast, plasma corticosterone levels were markedly elevated throughout the duration of the stress. Pituitary CRF receptor content, measured by binding of [125I]Tyr-ovine CRF to pituitary membrane-rich fractions, was unchanged after 2.5 h, but was reduced by 28 ± 2.7% (±SE) and 47.6 ± 1.1% after 18 and 48 h of immobilization, respectively. These results were confirmed by autoradiography in slide-mounted frozen pituitary sections. In contrast, no changes in CRF receptor content were observed in brain areas, including olfactory bulb, frontoparietal cortex, hippocampus, amygdala, and lateral septum. A concomitant decrease in immunoreactive (ir) CRF content in the median em...

Anatomical substrates of cholinergic‐autonomic regulation in the rat

Abstract: Acetylcholine (ACh) plays a major role in central autonomic regulation, including the control of arterial blood pressure (AP) Previously unknown neuroanatomic substrates of cholinergic - autonomic control were mapped in this study Cholinergic perikarya and bouton-like varicosities were localized by an immunocytochemical method empolying a monoclonal antiserum against choline acetyltransferase (ChAT), the enzyme synthesizing ACh In the forebrain, bouton-like varicosities and/or perikarya were detected in the septum, bed nucleus of the stria terminalis, amygdala (in particular, autonomic projection areas AP1 and AP2 bordering the central subnucleus, hypothalamus rostrolateral/innominata transitional area, perifornical, dorsal, incertal, caudolateral, posterior [PHN], subparafascicular, supramammillary and mammillary nuclei Few or no punctate varicosities were labeled in the paraventricular (PVN) or supraoptic (SON) hypothalamic nuclei In the mid and hindbrain, immunoreactive cells and processes were present in the nucleus of Edinger-Westphal, periaqueductal gray, parabrachial complex (PBC), a periceruleal zone avoiding the locus ceruleus (LC), pontine micturition field, pontomedullary raphe, paramedian reticular formation and periventricular gray, A5 area, lateral tegmental field, nucleus tractus solitarii (NTS), nucleus commissuralis, nucleus reticularis rostroventrolateralis (RVL), and the ventral medullary surface (VMS) In the PBC, immunoreactive varicosities identified areas previously unexplored for cholinergic autonomic responsivity superior, internal, dorsal, and central division of the lateral subnucleus, nucleus of Koelliker-Fuse and the medial subnucleus In the NTS, previously undescribed ChAT-immunolabeled cells and processes were concentrated at intermediate and subpostermal levels and distributed viscerotopically in areas receiving primary cardiopulmonary afferents In the nucleus RVL, cholinergic perikarya were in proximity to the VMS and medial to adrenergic cell bodies of the C1 area Punctate varicosities of unknown origin and dendrites extending ventrally from the nucleus ambiguus overlapped the C1 area and immediate surround of RVL In conclusion: 1) Cholinergic perikarya and putative terminal fields, overlap structures that are rich in cholinoreceptors and express autonomic, neuroendocrine, or behavioral responsivity to central cholinergic stimulation (PHN, NTS, RVL) The role of ACh in most immunolabeled areas, however, has yet to be determined Overall, these data support the concept that cholinergic agents act at multiple sites in the CNS and with topographic specificity (2) The absence of immunoreactive elements in the LC, PVN, and SON was unexpected and suggests that cholinergic processing attributed to these nuclei is mediated polysynaptically or by synapses on processes extending into adjacent cholinoreceptor fields (3) Putative cholinergic terminals overlapping sites that relay primary (NTS) or higher-order visceral afferents suggest anatomical substrates for cholinergic regulation of autonomic reflexes (4) ChAT-immunoreactive terminals in areas where cells project to the IML support the view that central cholinergic stimulation provoking sympathoexcitation may be mediated by bulbospinal neurons A rich plexus of varicose fibers overlapping the C7 area of RVL, which provides the excitatory drive for tonic sympathetic discharge, may form the anatomical basis for the increases in sympathetic nerve activity provoked by systemic or central administration of cholinergic agents