Effect of Growth Hormone Upon Thyroid Secretion Rate in the Rat.

Abstract

The effect of 1 mg/day growth hormone (GH) upon thyroid activity has been studied in non-lactating and lactating rats. GH did not alter thyroid secretion (TSR) or affect rate of release of thyroidal I131 in nonlactating rats though body weight was increased 2 g/day. During days 8-16 of lactation, the average TSR of 2.9 [mu]g/100 g L-thyroxine for lactating rats receiving GH was significantly greater than the 2.2 [mu]g/100 g obtained for untreated lactating rats. Rate of release of thyroidal I131 also was significantly increased suggesting GH in some manner effects an increase in output of TSH or thyroid hormones in the lactating rat.