Joan Vernikos-Danellis

Brain serotonin and pituitary-adrenal function

Publisher Summary This chapter describes the serotonin (5-HT) and pituitary-adrenal function. The effects of altering 5-HT synthesis on the diurnal rhythm of plasma corticosterone and on the pituitary adrenal response to stress were studied in rats and man. The hypothesis is proposed that 5-HT mediates the corticosteroid negative feedback mechanism that regulates corticotrophin (ACTH) secretion and that the primary site of this feedback is extra hypothalamic. In contrast, pretreatment with I-tryptophan, 5-HTP alone or 5-HTP and MK 486 reduced slightly the stress response in intact rats and 5-HTP with MK 486 reduced 24 h urinary 17-hydroxycorticosteroids (17-OHCS) excretion in humans. On the other hand corticosterone administration or stress increased the activity of tryptophan hydroxylase in the midbrain and the conversion of tryptophan to 5-HT. In addition, there appears to be a correlation between the daily rhythm of 5-HT content in the limbic system and that of circulating corticosterone. It is reported that treatment with parachlorophenylalanine (PCPA) abolished the diurnal variation of plasma corticosterone at an intermediate level in the rat, affect the metabolism or action of 5-HT abolished the daily rise in plasma 17-OHCS in the cat but did not block the response to stress.

Serotonin involvement in pituitary-adrenal function

Experiments clarifying the effects of serotonin (5-HT) in the regulation of the hypothalamic-pituitary-adrenocortical system are surveyed. Lesion experiments which seek to determine functional maps of serotonergic input to areas involved in regulation are reported. Investigations of the effects of 5-HT levels on the plasma ACTH response to stress and the diurnal variation in basal plasma corticosterone are summarized, and the question of whether serotonergic transmission is involved in the regulation of all aspects of pituitary-adrenal function is considered with attention to the stimulatory and inhibitory action of 5-HT.

Compensatory hypertrophy and phenylethanolamine n-methyl transferase (PNMT) activity in the rat adrenal

Compensatory hypertrophy effects on adrenal phenylethanolamine n-methyl transferase /PNMT/ activity in rats

Effects of chronic melatonin and saline injections on pituitary adrenal secretion

Es wurde festgestellt, dass Melatonin, ein angebliches Hormon aus der Pinealis, keine spezifische Wirkung auf die Sekretion von ACTH aus dem Hypophysenvorderlappen hat.