Abstract: Objective To observe the effects of the synthetic non-steroidal compound diethylstilbestrol on the ovarian folliclar development in the prepubertal mice and rats, and the involved mechanisms in the follicular synchronization resulted from the diethylstilbestrol treatment. Methods The prepubertal mice and rats were treated by intraperitoneal injection of a certain dose of diethylstilbestrol, and then the ovaries were collected to count the number of tertiary follicles in the ovary by serial sectioning and HE staining. On the other hand, the immunohistochemistry and immunoblotting methods were used to detect the distribution and quantity of Ubiquitin Carboxyl Terminal Hydrolases L1 (UCH-L1), c-Jun activation domain binding protein1 (Jab1), and cyclin dependent kinase inhibitive factor (p27^Kip1) in the ovaries, separately. Results Immunohistochemical results showed that the localization of UCH-L1 was only restricted into oocytes, Jab1 was detected in the oocyte nuclei of secondary follicles and tertiary follicles, and p27^Kip1 was distributed extensively in the ovary. Only considering the oocyte, in response to DES treatment, UCH-L1 and Jab1 staining signals were enhanced, and p27^Kip1 signal was become weak in the nucleus, similar to the situation in the tumor cells. However, the protein levels of all UCH-L1, Jab1 and p27^Kip1 in ovaries were showed increasing tendency in the DES-treated group to some degrees compared with naive group. In similarly rising tendency, the protein levels of UCH-L1 and p27^Kip1 were changed with the age in the ovaries of 1-4 week old mice though Jab1 was found no obvious change. Conclusion Intraperitoneal injection of diethylstilbestrol caused ovarian follicular growth synchronization, and involved mechanisms may be that UCH-L1 and its associated protein Jab1 down-regulated p27^Kip1 in the oocytes nucleus during the diethylstilbestrol-induced follicular growth synchronization.

Key words: Diethylstilbestrol, Puberty, UCH-L1, Follicle synchronization