Autophagy has been demonstrated as an important regulatory mechanism in the apoptosis of luteal cells during the regression of corpus luteum (CL) in the pseudopregnant rat ovary. However, the role of autophagy during the rat pregnancy still remains unknown. Therefore, the present study was designed to investigate the expression and contribution of autophagy to the luteal development and function in the pregnant rats. Ovaries were obtained from the female rats at the early, middle or late phase

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... f the pregnancy, which correspondingly had three groups, including the early (ELP), middle (MLP) and late luteal phase (LLP). The results of autophagy-associated protein LC-3 showed that autophagy expressed during the pregnant CL and significantly increased during the late luteal phase, which was further confirmed by the mRNA and protein expression changes of the other two autophagy related proteins, Beclin-1 and Atg-5. These results indicated autophagy may play an important role in the luteolysis. Further examinations of cellular apoptosis marker protein cleaved caspse-3 and ovarian prostaglandin 2α (PGF 2α) levels found that cleaved caspse-3 dramatically increased during the late luteal phase which consistent with the changes of autophagy, while ovarian PGF 2α level significantly increased during the middle luteal phase and dramatically decreased during the late luteal phase. Together, these results suggested that autophagy may be induced by PGF 2α and then contributed to the luteolysis through cellular apoptosis during the late luteal phase of pregnant ovaries. To our knowledge, this will provide a new insight into the important mechanism regulating the luteolysis of the pregnant ovaries in mammals.