In situ localization of messenger ribonucleic acid for an oviduct-specific glycoprotein during various hormonal conditions in the golden hamster.

The oviductal epithelium secretes specific glycoproteins that associate with the egg after ovulation. Several published reports including our preliminary studies have suggested that ovarian steroids regulate the secretion of oviduct-specific glycoproteins in several mammalian species. The objective of this study, using golden hamsters, was to analyze the hormonal effects on gene expression of these molecules more precisely during various hormonal conditions (estrous cycle, ontogeny, pregnancy, GnRH analogue treatment, and ovariectomy) by in situ hybridization. The message for the hamster oviduct-specific glycoprotein (HOGP) was detected by a digoxigenin-labeled single-strand specific DNA probe in paraffin sections. Data from these studies show the following. 1) In the oviduct, the signal was detected in both the perinuclear region and the basal region in the ampulla but was predominantly detected in the basal region in the isthmus. 2) The signal intensity was high in the ampulla compared with the isthmus. 3) During a normal estrous cycle, the message level was significantly altered between the estrous and diestrous stages in the ampulla but not in the isthmus. In addition, the signal did not disappear at any stage in either the isthmus or ampulla. 4) The HOGP message was first observed from around 14 days of age and then decreased in parallel with serum estradiol levels during aging. 5) The signal was also observed in the oviductal epithelium of pregnant animals at term and of postpartum animals. 6) When we treated the animals with TAP-144-SR (GnRH analogue) or performed an ovariectomy, which caused diminution of serum estradiol and progesterone levels, the message of HOGP was significantly decreased. Moreover, the message expression was greatly induced after estradiol administration to GnRH analogue-treated animals, whereas a high level of serum progesterone slightly inhibited HOGP message expression. These results suggest that elevation of the serum estradiol/ progesterone level affects the HOGP gene expression in the ampulla. However, a high serum estradiol level did not induce the gene expression rapidly, suggesting that an adequate serum hormonal level over a given period of time may be important for the HOGP gene expression.