Materials and Methods: Biopsies were obtained from mares on day of ovulation (d0, n=4), late diestrus (LD, n=4) and after luteolysis in the beginning of estrus phase (AL, n=4) of the cycle and days 14 (P14, n=4), 18 (P18, n=4), and 22 (P22; n=4) of pregnancy. Total RNA was isolated from the endometrial tissues and was converted to cDNA. Relative mRNA expression levels of genes were quantified using quantitative polymerase chain reaction (qPCR). GAPDH was used as reference gens. A mixed model was fitted on the normalized data and least significant difference (LSD) test was employed to determine significantly different groups.

Results: PTEN expression at mRNA level was detected in equine endometrium during all stages of estrous cycle and early pregnancy. Compared to LD, PTEN expression tended to decrease at AL. Similarly, comparing to the d0, the expression was lower during early pregnancy days including P14, P18 and P22, but did not reach to significance (P>0.10). PTEN is expressed in equine endometrium and its level appears to be downregulated at cycle and early pregnancy.

Conclusion: It is important to investigate PTEN activity and expression at protein level.