Ovarian Carbonyl Reductase Delayed Onset of Persistent Estrus in the Offspring of Parathyroidectomized Mother Rats

Abstract

ABSTRACT-We investigated the effects of maternal parathyroidectomy on day 5 of pregnancy on the ovarian carbonyl reductase (CR) in the offspring of rats. Changes in the ovarian CR of the offspring were examined at 4 and 8 months of age. In 8-month-old female offspring, the ovarian weight and the ovarian CR activity were significantly higher in rats from parathyroidectomized mothers than in rats from sham-operated mothers, and the offspring of the parathyroidectomized mothers showed the regular 4-day estrous cycles at 8 months of age, while the offspring of the sham-operated mothers were in the state of persistent estrus. Furthermore, intense immunostaining was found in the theca interna cells and the interstitial gland cells in the ovary of rats from the parathyroidectomized mothers, whereas in the ovary of the age-matched normal rats, immunostaining was faint. These results suggest that the maternal parathyroidectomy affect the activity and localization of CR in the ovary of female offspring.Keywords: Carbonyl reductase, Parathyroidectomy in pregnancy, Ovary, Persistent estrus Fujii (1) has reported for the first time that the characteristic response of serum calcium to parathyroid removal in the first (Fl) generation rats from mothers parathyroidectomized on day 5 of pregnancy (Px-F1 rats) is inherited into the third and fourth generations. Moreover, Fujii and Yamamoto (2) have reported that female Px rats show the regular 4-day estrous cycle over 12 months of age, whereas rats from sham-operated mothers (normal rats) show persistent estrus and demonstrated that the aging process of the hypothalamopituitary-ovarian axis in Px rats is delayed. On the other hand, Caplan and Beguin (3) have reported that in patients with hypoparathyroidism, requirements for calcium and vitamin D decline significantly during lactation.We have already purified and characterized carbonyl reductases (CRs, EC 1.1.1.184) from rat ovary (4) and testis (5) and human testis (6). CR catalyzes the NADPH-dependent reduction of a variety of endogenous and xenobiotic carbonyl compounds to the corresponding alcohols, and it is known as prostaglandin 9-keto reductase. Indeed, CRs from rat ovary and testis have both prostaglandin 9-keto reductase and prostaglandin 15-keto reductase activity with comparatively low Km (4, 5). The ovarian CR has been demonstrated to be induced by luteinizing hormone/human chorionic gonadotropin (LH/hCG), and the induction is potentiated by estrogen in immature (7-9) and mature (10, 11) rats. In the present study, we investigated changes in the ovarian CR activity and its content in Px-F1 rats. MATERIALS AND METHODS AnimalsVirgin female Wistar-Imamichi strain rats (8-weeksold) were purchased from the Institute for Animal Reproduction (Ibaragi) and housed in group cages under controlled conditions of light (14 hr on, 10 hr off) and temperature (241C). Food and water were always available. Rats were made pregnant by mating with fertile males, and pregnancy was confirmed by the presence of vaginal sperm on day 0. On day...