[Increased sensitivity of hypophyseal cells from neonatal rats to bromocriptine and melatonin].

Age-related peculiarities of the bromocriptine and melatonin effect on macromolecule biosyntheses in cultured rat pituitary cells were studied during long-term (3 day) incubation. Bromocriptine (10(-9)-10(-7) M) caused dose-dependent inhibition of DNA synthesis in pituitary cells of neonatal rats, but only in maximal dose (10(-7) M) it decreased significantly this parameter in pituitary cells of adult animals. Melatonin (10(-8)-10(-6) M) caused significant inhibition of DNA synthesis in cultured cells of neonatal rat pituitaries. However, melatonin did not change DNA biosynthesis in pituitary cells of adult rats. The results obtained permit us to suggest certain contribution of dopaminergic tone and melatonin to the control of proliferative activity of rat pituitary in neonatal period of development.