Elevated catecholamines in porcine follicular fluid before ovulation.

The purpose of this study was to correlate changes in catecholamine concentrations in porcine follicular fluid and cyclic events in the ovary. Follicular fluid was aspirated from follicles of ovaries obtained from pigs throughout the 21-day estrous cycle and analyzed for norepinephrine (NE), epinephrine (EPI), and estradiol (E2). Serum was obtained from cycling pigs on days 6-10 and 16-20 of the cycle and assayed for NE, EPI, E2, and progesterone. The concentrations of NE in the follicular fluid were relatively constant during days 1-15 of the luteal phase (1.7 +/- 0.2 ng/ml), but were elevated significantly to 2.9 +/- 0.4 ng/ml during the follicular phase (days 16-20). EPI had a similar profile, but a 6- to 10-fold lower concentration. The follicular fluid E2 concentration increased from 15.6 to 76.5 ng/ml during the luteal phase to 630 ng/ml during the follicular phase. Serum NE and EPI concentrations were similar during midluteal and follicular phases, whereas progesterone and E2 were significantly elevated during the luteal and follicular phases, respectively. These results indicate that catecholamines in follicular fluid are elevated significantly during the follicular phase of the estrous cycle and may have a physiological role in preovulatory events as well as during the luteinization process.