ROLE OF PHOSPHODIESTERASE IN CYCLIC NUCLEOTIDE SIGNALING DURING OVARIAN FOLLICULAR DEVELOPMENT IN THE RAT

Cyclic nucleotides, cyclic AMP (cAMP) and cyclic GMP (cGMP), as second messages play potential roles in the mammalian ovarian functions. The cellular level of cyclic nucleotide (cAMP/cGMP) is largely dependent on the activity of phosphodiesterase (PDE) which degrade cAMP/cGMP. In order to examine the role of phosphodiesterase (PDE) in cAMP/cGMP signaling during follicular development, the present study was conducted to investigate ovarian cAMP/cGMP levels and PDE activities in postnatal rats, immature rats during gonadotropin-primed follicular development, ovulation and luteinization, adult rats during normal estrous cycle, and aged rats that spontaneously developed persistent estrus (PE) by radioimmunoassay (RIA). All four rat models were conformed by histological examination of one ovary and the other ovary was used for RIA. In all four rat models, ovarian cAMP and cGMP levels were significantly changed, while, the related PDE activities were also changed significantly but in different manners. Together, our findings indicate that roles of cAMP and cGMP signal pathways, and related PDE are involved in ovarian physiological processes, such as ovarian follicular development, atresia and luteinization by a stage-dependent manner. (poster)