Expression of prolactin receptor mRNAs in ovaries of senescence accelerated mice

Abstract

Some corpora lutea (CLs) are abnormally accumulated in the ovaries of female SAMP mice. We investigated the relation between abnormally accumulated CLs (aaCLs) and expression of mRNAs of four prolactin (PRL) receptors (PRLRs) in SAMP mice. Each CL was isolated, and then mRNA expression levels of long form, short form1, short form2 and short form3 PRLRs were estimated by real time quantitative RT-PCR technique. A high level of expression of long form PRLR mRNA was noted in all CLs of SAMP and SAMR. Weak levels of short form1, short form2 and short form3 PRLR mRNAs were detected in functional CLs of SAMR mouse ovaries, and higher levels of these three mRNAs were noted in regressing CLs, as estimated by 20α-hydroxysteroid dehydrogenase mRNA expression. Interestingly, negative/trace expression levels of the short form receptors were seen in functional or regressing CLs of SAMP mice. We suppose that the long form PRLR mRNA is dominantly expressed in CLs in murine ovaries, and increased expression of short form PRLRs regulates luteolysis, and that reduced expression of short form PRLRs in CLs of SAMP mice may inhibit CL regression and cause abnormal accumulation of CLs.