CENTRAL NERVOUS CONTROL OF PROLACTIN SECRETION IN THE RABBIT: EFFECT OF LOCAL OESTROGEN IMPLANTS IN THE AMYGDALOID COMPLEX

Abstract

SUMMARY Virgin female New Zealand White rabbits were made pseudopregnant by i.v. injection of human chorionic gonadotrophin. Seventy-six animals received bilateral implants of oestradiol monobenzoate in the amygdaloid complex and neighbouring regions of the brain on the 7th day of pseudopregnancy; 15 animals were given daily injections s.c. of 20 i.u. ovine prolactin from day 7 to 17, and 21 animals served as controls, four of which were implanted bilaterally with blank steel tubes on day 7. All animals were killed on day 18 of pseudopregnancy. At autopsy, lactogenic responses were present in 20 of the animals with implants. Lactogenesis occurred when oestrogen implants had been placed in the medial nucleus, in the central nucleus and in the basomedial part of the basal nucleus of the amygdala, as well as in the stria terminalis. It is suggested that the lactogenic responses may have been caused by oestrogen-sensitive neurones in the amygdala acting via the stria terminalis on the preoptic area and/or basal hypothalamus to cause the release of prolactin, and that the amygdala may play a role in the normal animal, via the hypothalamo-hypophysial system, in the modulation of the secretion of prolactin by the anterior pituitary.