Follicular and luteal function in the puberal rat: gonadotrophic hormone stimulation and enzymic-nucleotide interactions

ABSTRACT Using the puberal rat and the PMS-treated rat as animal systems, ovarian events associated with follicular and luteal development have been characterized by measuring gonadotrophic hormone (LH, FSH and prolactin) and progesterone concentrations in peripheral serum; and selected enzymic (NAD-kinase:NAD-K and glucose-6-phosphate dehydrogenase: G6PD) activities and nucleotide (NAD, NADH, NADP, NADPH, ATP) concentrations in ovarian tissue. In the puberal rat, the period of follicular development was characterized by increased ovarian NAD-K SA, NAD and NADH concentrations and decreased ATP and NADP concentrations. The first pro-oestrus was characterized by greatly elevated LH, FSH, prolactin and progesterone concentrations, significant decreases in ovarian NAD-K SA, NAD, NADP and ATP concentrations, and an increase in NADPH concentrations. The development of new corpora lutea was associated with striking increases in ovarian NAD-K SA and G6PD SA. Increased activity of both enzymes exhibited a significant positive coefficient of correlation with the number of corpora lutea contained within the ovarian tissue. PMS (4 IU) stimulation of follicular activity resulted in events leading to the induction of an endogenous LH surge and ovulation. Associated with increased follicular activity was increased ovarian NAD-K SA. In contrast to the puberal rat, no rise in progesterone concentrations was associated with the LH surge or the formation of corpora lutea.