ASSOCIATION OF EXPRESSION OF MESSENGER-RNA ENCODING THE PGF(2-ALPHA) RECEPTOR WITH LUTEAL CELL APOPTOSIS IN OVARIES OF PSEUDOPREGNANT MICE

The relationship between the expression of mRNA encoding the prostagla ndin F-2 alpha (PGF(2 alpha)) receptor and luteal cell apoptosis as de termined by oligonucleosome formation was determined in mouse corpora lutea on days 2 (early phase), 6 (mid-phase), and 11 and 13 (late phas e) of pseudopregnancy. No signals for mRNA encoding the PGF(2 alpha) r eceptor were detected in the ovary as shown by RNA blot analysis of pr egnant mares' serum gonadotrophin (PMSG)-treated mice. The expression of the mRNA that could be detected in the corpora lutea on day 2 after hCG treatment was low, but it was increased on day 6 and reached a pl ateau on days 11 and 13. On days 11 and 13, in situ hybridization sign als for mRNA encoding the PGF(2 alpha) receptor were localized to larg e luteal cells of the corpora lutea, especially the cells in the super ficial layer. However, ethidium bromide staining revealed marked oligo nucleosome formation in the corpora lutea on days 11 and 13. Similarly , positive signals of in situ nick-DNA-end labelling were also detecte d in the corpora lutea on days 11 and 13. Analysis of the adjacent sec tions of the corpora lutea on day 13 showed that both signals for DNA strand breaks and mRNA encoding the PGF(2 alpha) receptor were co-expr essed in the corpus luteum. These results suggest that apoptosis durin g structural luteolysis closely associates with the increased expressi on of mRNA encoding the PGF(2 alpha) receptor in luteal cells of pseud opregnant mice.