DIFFERENTIAL EFFECTS OF PERMANENT HYPOTHALAMIC LESIONS ON REPRODUCTION AND LACTATION IN RATS

Abstract

SUMMARY The recovery, growth, reproductive and lactational performances of rats in which thermal hypothalamic lesions had been made in one of seven different placements are described. Small medial lesions failed to alter any of the observed functions while small lateral lesions were followed by a high postoperative death rate, impaired growth, lowered mature live weight, elevated incidence of prolonged gestation and of stillbirths after normal gestations, and uniform failure of operated animals to lactate after parturition. Two large anterior lesions are described following both of which lactation failure was again present, but other functional impairments were not always similar to those described for rats with the small lateral lesions. These results are described in relation to earlier findings and to the possibility of differential location of mechanisms within the hypothalamus responsible for control over the endocrine factors implicated in the functional disturbances.