Endometrial expression of progesterone, estrogen, and oxytocin receptors and of 20a-hydroxysteroid dehydrogenase and cyclooxygenase II2 and 5 days after ovulation in induced short and normal estrous cycles in dairy cows

摘要

The aim of this study was to investigate causes of the short estrous cycles that occur frequently in dairy cows after estrus synchronization using PGF_(2alpha) and GnRH. Expression of oxytocin receptor (OR), progesterone receptor (PR), and estrogen receptor (ER); of cyclo-oxygenase II (COX-II) and 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD); and of peripheral blood estradiol-17beta and progesterone (P4) concentrations were analyzed in estrous cycles of normal length and in induced short estrous cycles. On Day 8 (ovulation = Day 0), presynchronized dairy cows (n = 14) were given 0.15 mg of dexcloprostenol and 0.1 mg of gonadorelin 24 hours later. Animals were bled once daily for P4 and estradiol-1715 analyses, and endometrial biopsy specimenswere taken on Days 2 and 5 for PR, ER, OR, 20alpha-HSD, and COX-II determinations with immunohistochemistry and/or real-time quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR). Ovulations and ovarian structures were monitored with transrectal ultrasound daily until the next ovulation. After excluding one case of incomplete luteal regression, short estrous cycles occurred in 8 of 13 cases (length from 8 to 12 days). No differences were established in endometrial ER, PR, or COX-II expression between the normal and short cycle groups in the semi-quantitative immunohistochemistry analysis. In qRT-PCR analysis, no differences were found in relative gene expression of endometrial ER, PR, OR, 20alpha-HSD, or COX-II between normal and shortcycles. Despite evidence from previous studies that short estrous cycles are induced by premature prostaglandin release, differences in these receptors or in enzyme expression do not explain the release.