[Uterine response to estrogen in the rat of hypothyroidism]

Hypothyroidism has been believed to affect the female reproductive system, but relatively few studies have been made on the direct effects of the thyroid hormone on the uterus, and the results have been conflicting. In the present paper, thymidine kinase (TK) and progesterone receptor (PrgR) in cytosol were assayed in the rat to study the uterine response to estrogen. Furthermore, this uterine response to estrogen was compared between hypothyroid and euthyroid rats. Hypothyroidism was induced by surgical operation performed at 21 days of age. Immature rats: Estradiol (E2) was injected on day 26. No significant difference in increases of uterine wet weight, TK and PrgR was noted between hypothyroid and euthyroid rats 30 h after E2 injection. Adult rats: Ovariectomy was added at 21 days or 65 days of age. E2 was injected on day 70. No significant difference in increases of uterine wet weight, TK and PrgR was noted between hypothyroid and euthyroid rats 24 h or 48 h after E2 injection. These results suggest that hypothyroidism may have no direct effects on such uterine responses to estrogen as wet weight, TK and PrgR.