The quantitative expression of peroxisome proliferator activated receptor (PPAR) genes in porcine endometrium through the estrous cycle and early pregnancy.

Peroxisome proliferator activated receptors (PPAR) are a family of the nuclear receptors which play an important role as transcriptional factors. The aim of the present study was to determine the expression of PPARs (α, β, γ) mRNA in the porcine endometrium during the estrous cycle and periimplantation period. Gilts were divided into two groups (cyclic and pregnant), synchronized and superovulated. The animals from the first group were slaughtered throughout the estrous cycle: 2-4, 5-8, 9-10, 11-12, 13-15, 16-17 and 18-21. Gilts from the second group were inseminated and slaughtered at different days of pregnancy to create subgroups: 5-8, 9-10, 11-12, 13-15, 16-17, 18-21, 21-30. PPAR mRNA expression in the endometrium was analyzed by real-time PCRs. During the estrous cycle the expression of PPARγ1 mRNA was significantly higher on days 13-15 than at the remaining stages. The expression of PPARα and β transcripts showed a similar pattern and the lowest levels were observed on days 2-4, 16-17 and 18-21 in comparison with the remaining stages (days 5-8, 9-10, 11-12). During pregnancy a significant increase in the expression of PPARγ1 mRNA was noted on days 16-17, 18-21 and 22-30 compared to earlier stages. The transcript level of PPARβ was significantly lower on days 11-12 and 22-30 than on days 5-8, 9-10, 13-15. mRNA expression of PPARα was high on days beginning from 5-8 until 18-21 and significantly dropped on days 22-30. The results indicate that the endometrial expression of PPARs genes fluctuates during the estrous cycle and pregnancy. PPARα and PPARβ transcript levels show similar profiles during the estrous cycle. The decrease of both transcripts concentration on days 10-12 and 22-30 days in pregnant gilts implicates their role in maternal recognition of pregnancy and the end of implantation, respectively.