Hypothalamus serotonin action

In addition to its presumed role as a neurotransmitter within the brain, serotonin is synthesized in the pineal gland, where it is a precursor for the synthesis of melatonin, a hormone that influences endocrine activity, presumably by an action within the hypothalamus. 

Somatostatin, growth hormone release inhibiting hormone, occurs in other parts of the brain as well as in the hypothalamus, and also in some peripheral tissues, e.g. pancreas, stomach. In addition to the action implied by its name, it inhibits secretion of thyrotrophin, insulin, gastrin and serotonin. 

Cyproheptadine stimulates appetite, through actions on serotonin receptors in the ventrolateral hypothalamus. 

The hypothalamus and amygdala, prominently associated with both testosterone and serotonin, play a key role in aggressive responses to situations in which efforts at dominance are frustrated. He notes that low serotonin levels have been found in the hypothalamus and the amygdala in aggressive animals, and that testosterone action in both of these brain structures has been shown to increase aggression in various animal species. ... 

One important neuronal TRH control center appears to be the paraventricular nucleus, but TRH Is widely distributed in the hypothalamus and highly concentrated in the median eminence (4). One important ipactor regulating TRH production is environmental temperature. Both peripheral thermal receptors and preoptic neuronal thermal receptors monitor environmental and central body temperature these receptors modulate preoptic neuronal outflow to the paraventricular nucleus and other TRH synthesizing neurons in the hypothalamus and median eminence which. In turn, modulate TRH secretion (4). Decreasing environmental and/or core body temperature Increase TRH output and increase the tonic level of TSH release. Somatostatin (SRIF) and dopamine can inhibit TSH release by actions at the pituitary level, and these inhibitory transmitters contribute to central nervous system modulation of TSH release (4). There is evidence that serotonin may be inhibitory in the adult rat, but this does not seem to be so in other species. Norepinephrine also may be inhibitory. Glucocorticoid can inhibit TSH release at the hypothalamic level, but the mechanism is not known. The exact roles of TRH and non-TRH regulatory factors in TSH control are not clear. Administration of somatostatin antiserum to adult rats increases basal TSH levels and potentiates the TSH response to cold (19). Inhibitory factors probably also play a role in the diurnal variation in TSH secretion, in the inhibitory reactions to stress, in the variation in thyroidal activity in psychosis, etc. 

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