Developmental and periovulatory changes of ovarian norepinephrine in the rat

Norepinephrine (NE) and dopamine (DA) contained in the rat ovary were determined by high-performance liquid chromatography with electrochemical detection. Concentration of ovarian NE reached adult levels around 5 weeks of age, when the first ovulation occurs. During induction of ovulation, the ovarian NE contents increased slightly during the preovulatory phase, followed by a significant decrease in the postovulatory phase, whereas the turnover of ovarian NE decreased during the preovulatory phase. These results suggest that ovarian noradrenergic nerves were in a somewhat inactivated state during the preovulatory phase. Therefore, ovarian sympathetic nerves are considered to participate in mechanisms of the onset of puberty and ovulation.