Further observations on the teratogenic action of the thyroid stimulating hormone.

Pregnant Wistar Albino rats were injected intraperitoneally with the thyroid stimulating hormone (TSH), obtained from several different suppliers, and with the dye trypan blue. Twenty USP units of TSH were injected on days 7 to 10 of pregnancy, one quarter of the total dose each day. Trypan blue was injected as a single subteratogenic dose (0.6 mg/100 gm maternal body weight) on day 8. Autopsy was on day 20. Some TSH prepared as a pituitary extract possessed very weak teratogenic activity, possibly limited to the production of hydronephrosis and hydroureter. Other TSH samples similarly prepared had no embryotoxic or teratogenic effect. Thyrotropin prepared from bovine serum exhibited distinct teratogenic activity causing the production of various malformations in the offspring of treated mothers. A subteratogenic dose of trypan blue enhanced the teratogenic activity of the serum prepared TSH sample but had no effect on TSH prepared from pituitary glands. The results of this experiment suggest that there is something in the nature of preparation of TSH from bovine serum that causes it to possess teratogenic activity. The thyroid stimulating hormone (TSH) was first reported to possess teratogenic activity in rats by Beaudoin and Roberts ('66). A re-evaluation of the original report is necessary in light of the results to be presented in this paper. This study was undertaken to test the teratogenic activity of samples of TSH obtained from several different suppliers. Each TSH sample was also tested for possible interaction with the disazo dye trypan blue. MATERIALS AND METHODS Virgin female Wistar Albino rats (Albino Farms, Red Bank, New Jersey) were used. The animals were maintained on a Rockland Complete Rat Diet ad libitum, with supplemental feedings of lettuce. Day 0 of pregnancy was considered to begin on the morning sperm were found in the vaginal smear. Two experimental groups of rats were used in this study; the first group received thyrotropin alone and the second group received trypan blue in addition to thyrotropin. The thyroid stimulating hormone was prepared in sterile saline and 20 USP units were administered intraperitoneally in one-quarter doses at 24-hour intervals on days 7, 8, 9, and 10 of gestation. Trypan blue was prepared as a 0.12% solution and injected intraperitoneally on day 8 of pregnancy, in a subteratogenic TEBATOLOGY, I : 11-20. dose of 0.6 mg per 100 gm maternal body weight. Pregnancy was terminated on day 20, uterine resorption sites were counted, and the fetuses were recovered, weighed, and fixed in Bouin's fluid or 95% alcohol for subsequent examination for malformations. The fetuses fixed in 95% alcohol were prepared for staining with alizarin red for visualization of the skeleton. Fetuses fixed in Bouin's fluid were free-hand sectioned with a razor blade into 2 mm slices and each slice examined for malformations. The thyrotropin used in this study was obtained from The Endocrinology Study Section of The National Institutes of Health (NIH); Sigma Chemical Co., St. Louis, Missouri; Armour Pharmaceutical Company, Chicago, Illinois; and Nutritional Biochemicals Corp. (NBC), Cleveland, Ohio. All thyrotropin samples were prepared from pituitary glands except one from NBC that was prepared from bovine serum.