Decrease in Pituitary Growth Hormone Level in Rat after Prolong Administration of Bovine Thyrotropin

Abstract

Female Fisher rats aged 35 days were injected intraperitoneally with 50 μg and 100 μg per day of bovine thyrotropin(TSH) for 44 days. GH content and concentration in the TSH treated groups were significantly lower than that of the control group. Wet weight of anterior pituitary and thyroid gland were not altered by TSH treatment, while the doses of 100 μg TSH significantly lowered adrenal, ovarian and uterine weights. The formation of antibodies to bovine TSH after chronic administration, which can cross react to rat endogenous TSH, may lead to thyroid hypofunction which in turn lower pituitary GH synthesis. The bovine TSH antiserum may also cross react with rat FSH and LH and lead to adrenal and ovarian hypofunction.