Increase in thyrotrophin secretion by rat pituitary autografts after infusion of hypothalamic extracts.

Abstract

SUMMARY Thyroidal uptake and release of 131I were used to study the effects of prolonged infusion of porcine hypothalamic extract on the ability of rat pituitary autografts to secrete thyrotrophin (TSH). The extract used contained insufficient TSH to induce release of thyroidal 131I in hypophysectomized rats. After infusion for 10 days, the time of maximal uptake of 131I and onset of 131I release was significantly shortened by infusion of hypothalamic, but not cerebral cortical extract, when compared with non-infused autografted controls. The rate of release of thyroidal 131I was significantly increased by the infusion of hypothalamic extract so that by 96–120 h after the administration of 131I the rate of release was not significantly different from that in intact controls. Accelerated thyroidal release of 131I began 42–48 h after the application of hypothalamic extracts to pituitary autografts and fell rapidly after withdrawal of the extract. At the end of 14–17 days of infusion sections of the autografts contained aldehyde-fuchsin positive staining basophils.