Effects of induced maternal hypothyroidism on the ovarian development of offspring rats

Abstract

The effects of propylthyouracil (PTU) induced hypothyroidism of rats during pregnancy and lactation on offspring ovarian development and maturation were studied. Thyroid hormones and thyroid stimulating hormone (TSH) concentrations were determined using the radioimmunoassay method in order to verify the hypothyroid status of treated mothers and their two months old pups. The ovaries of the offspring were processed for light microscopy analysis on the day of the first estrus after the 60th day of age. Histological analysis including follicle count was performed on serial sections stained with haematoxyline/eosin and on semithin sections stained with methylene blue. A significant increase of serum TSH and decrease in T3 and T4 levels was observed in treated mothers compared to controls. The levels of measured hormones in the control and PTU-treated two months old rats were not significantly different. Ten percent of 60-dayold treated females did not reach estrus and they were sacrificed in diestrus. The secondary interstitial cells were the dominant structures in the ovaries. The number of healthy growing and early antral follicles was markedly decreased. Ovaries of treated rats contained relatively few antral follicles, significantly more atretic antral follicles and a decreased number of corpora lutea, compared to controls. These results indicate that lack of thyroid hormones during prenatal and early postnatal development impair ovarian development in rats.

U okviru ovog rada izučavan je uticaj hipotireoidizma majki izazvanog propiltiouracilom (PTU) tokom graviditeta i laktacije na razvoj i sazrevanje jajnika pacova. U cilju određivanja tireoidnog statusa majki i mladunaca, merena je koncentracija tireoidnih hormona i tireostimulirajućeg hormona (TSH) u serumu. Jajnici potomaka hipotireoidnih majki i kontrolne grupe sprovedeni su za analizu svetlosnom mikroskopijom na dan prvog estrusa posle 60. dana starosti. Analizirani su serijski isečci jajnika bojeni hematoksilinom i eozinom, kao i polutanki preseci bojeni metilenskim plavim. Koncentracija T4 i T3 značajno je smanjena u serumu tretiranih majki, dok je nivo TSH značajno povišen u odnosu na kontrole. Kod dva meseca starih kontrolnih i tretiranih ženskih potomaka nije bilo značajne razlike u nivou svih određivanih hormona. Deset procenata tretiranih životinja nije normalno ušlo u estrus do 60. dana, i žrtvovane su u fazi diestrusa. Sekundarne intersticijalne ćelije su dominantne strukture u jajnicima tretiranih pacova. Ukupan broj aktiviranih folikula je značajno smanjen uz izrazitu atreziju folikula, a smanjen je i broj žutih tela. Rezultati pokazuju da hipotireoidizam izazvan u toku graviditeta i laktacije dovodi do promena u razviću jajnika.