[Interrelation of prolactin and calcitonin]

Intraperitoneal prolactin injection (3.5 U/200 g bw, daily, for 5 days) caused a marked rise in blood calcitonin concentration in female Wistar rats. It is common knowledge that exogenous calcitonin administration results in an obvious drop of blood prolactin level. Hence, the interrelation between anterior pituitary lactotropic function and blood calcitonin level may be regarded as a negative feedback, since prolactin activates calcitonin production and secretion, with the latter, in its turn, inhibiting adenohypophysial lactotropic function.