THE EFFECTS OF HYPOTHALAMIC LESIONS ON GOITRO-GENESIS AND PITUITARY TSH SECRETION IN THE PROPYLTHIOURACIL-TREATED GUINEA PIG1

Abstract

Propylthiouracil (PTU)-induced goitrogenesis was selectively impaired in male guinea pigs by anterior hypothalamic lesions. These lesions also reduced or abolished the PTU-induced enlargement of the adenohypophysis and the increase of thyrotrophin (TSH) stores therein, without causing gonad atrophy. Afore posterior lesions affected TSH secretion less and did cause gonad atrophy. The findings are interpreted to mean that neither the synthesis nor the release of TSH can reach maximal levels in the absence of the neural structures which were damaged. IN HATS, appropriate hypothalamic lesions have been found to impair, but not abolish, thyrotrophin (TSH) secretion (1–5). In dogs, on the other hand, similar lesions seem to eliminate TSH secretion, or at least its release phase, since they reduce both thyroid size and I131 uptake to hypophysectomy-like levels (6). This apparent species difference in the extentto which TSH secretion may be decreased by hypothalamic damage suggests that further comparative studies, such as the one presented here, may be of value.