Hypothalamus Supraoptic nucleus

The neurotransmitter histamine (HA) exerts several functions in the hypothalamus [1-2] including an involvement in the neuroendocrine regulation of pituitary hormone secretion [3]. HA has no effect directly at the level of the pituitary gland, but influences the secretion of anterior pituitary hormones either by an exerted e.g. in the paraventricular nucleus (PVN) on other central transmitters or hypothalamic regulating factors, which subsequently regulate the release of anterior pituitary hormones. In addition, HA acts on the supraoptic nucleus (SON) in the hypothalamus where the posterior pituitary hormones are synthesized and thereby exerts a direct effect on the release of the posterior pituitary hormones. Immunohistochemical studies have revealed that the histaminergic neurons, which originate in the tuberomammillary nuclei of the posterior hypothalamus, densely innervate most of the hypothalamic areas involved in the neuroendocrine control of pituitary hormone secretion [4-5]. Within the last two decades the effect of HA on pituitary hormone secretion have been explored in several studies and it has been... 

High D4 receptor concentration has been described in the rat frontal and parietal cortex on the other hand, medium-high concentration of D4 receptor has been reported in the NAc, CPu, SNc, as well as in the hippocampus, entorhinal cortex, and medium-low concentration in the olfactory tubercle, GP, thalamus, supraoptic nucleus of the hypothalamus, cerebellum, and pituitary gland (Ariano et al., 1997b Defagot et al., 1997 Mauger et al., 1998). 

Fig. 1. Location of dopaminergic perikarya (Au-A15) are depicted schematically on frontal sections (B-F) through the diencephalon of the rat. Section A is a sagittal view of the rat brain depicting the rostrocaudal location of frontal sections B-F. Abbreviations AH, anterior hypothalamus ARC, arcuate nucleus BST, bed nucleus of the stria terminalis f, fornix ic, internal capsule inf, infundibulum me, median eminence mt, mamillothalamic tract OC, optic chiasm ot, optic tract PH, posterior hypothalamus PIT, pituitary gland PeV, periventricular nucleus PVN, paraventricular nucleus RCH, retrochiasmatic area SON, supraoptic nucleus VMN, ventromedial nucleus ZI, zona incerta.

Q3 Vasopressin is a small peptide hormone consisting of nine amino acids, most of which is synthesized in neurosecretory cells of the supraoptic nucleus of the hypothalamus. Small quantities are also produced in the neighbouring paraventricular nucleus. The hormone is transported down the axons of the neurosecretory cells via the infundibulum to the posterior pituitary, where it is stored until release into the blood is triggered by nerve impulses from the hypothalamus. Vasopressin is better known as antidiuretic hormone (ADH). The name vasopressin relates to its vasoconstrictor action, which increases pressure in the vascular system. This action was discovered before its effects on water retention were known. 

Oxytocin is a neuropeptide synthesized in the paraventricular and supraoptic nucleus of the hypothalamus. Oxytocin is released from axon terminals of the posterior pituitary into the bloodstream. It is also distributed to the central nervous system and oxytocin binding sites are found throughout, especially in the limbic system (Insel and Young, 2000). Oxytocin has been linked to afifiliative behavior, social memory, and behavior, all of which are impaired in autism (Insel et al., 1999). It has been hypothesized that dysfunction of oxytocin and vasopresin contributes to social impairment in autism (Waterhouse et al., 1996). 

Meeker RB, Swanson DJ, Greenwood RS, Hayward JN (1993) Quantitative mapping of glutamate presynaptic terminals in the supraoptic nucleus and surrounding hypothalamus. Brain Res 600 12-122. 

Preoptic region and hypothalamus Lateral preoptic area Medial preoptic area Medial preoptic nucleus Magnocellular preoptic nucleus Suprachiasmatic nucleus Supraoptic nucleus Anterior hypothalamic area Lateral hypothalamic area Periventricular nucleus Paraventricular hypothalamic nucleus Arcuate nucleus Dorsal hypothalamic area Ventromedial hypothalamic nucleus Dorsomedial hypothalamic nucleus Compact part Tuber cinereum Posterior hypothalamic area Premammillary nucleus Supramammillary nucleus Medial mammillary nucleus Lateral mammillary nucleus... 

Vasopressin (antidinretic hormone) is a nonapeptide that controls resorption of water by distal tubules of the kidney to regulate the osmotic pressure of blood. It functions to conserve body water by reducing the output of urine, and thus it is known as an antidiuretic. Vasopressin is synthesized in the supraoptic nucleus of the hypothalamus where it is bound to a neurophysin protein carrier, packaged in granules, and delivered by intracellular transport to nerve terminals in the posterior pituitary. Vasopressin bound to neurophysin is released from the granules in response to increased extracellular osmolarity sensed by hypothalamic osmoreceptors, signaling by atrial stretch receptors or after a rise in angiotensin n levels. Its secretion is increased by dehydration or stress and decreased after alcohol consumption. 

The presence of TRH in the hypothalamus had been suspected for at least a decade prior to its chemical identification as pyro-glutamyl-histidyl-proline amide in 1969 (Nl). It is known to be secreted over a wide area of the hypothalamus, particularly in the region of the supraoptic nucleus, although the exact cellular site of its synthesis is not known (S2). The TRH was first demonstrated in hypophysial portal... 

In the diencephalon, high concentrations were present in several thalamic nuclei, including portions of the ventral and geniculate nuclei. The supraoptic nucleus was the only hypothalamic nucleus with a high concentration of high-affinity GABA receptors. The hypothalamus generally had low quantities of receptors. Low levels were present in the retinal inner plexiform layer (Wamsley, Palacios, and Kuhar, personal communication). 

The neurosecretory neurones concerned with hormone synthesis are segregated into anatomically defined regions, termed nuclei, in the hypothalamus. The supraoptic nucleus is concerned primarily with the synthesis of antidiuretic hormone, whereas oxytocin is produced predominantly by neurones in the paraventricular nucleus. 

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