[Age-related features of neurohumoral regulation of somatotropic hormone secretion]

Experiments with primary cultures demonstrated a stimulating effect of TRF on somatotropic hormone (STH) secretion by hypophyseocytes of neonatal but not adult rats and a reduced reactivity of neonatal somatotrophs to the inhibitory effect of somatostatin during short-term incubation. No noticeable serotonin effect on STH release from hypophyseal cells of animals of various ages was observed. During prolonged (24 h) incubation a weak inhibitory effect of bromocriptine and melatonin on STH secretion by pituitary cells of neonatal but not adult rats was observed. These results permit us propose a similarity of the functional characteristics of neonatal pituitary somatotrophs to somatomammotroph properties.