Submission Number: GAR-4-10-36

Abstract Number: 301

OOCYTE-DERIVED CATECHOLAMINES: POSSIBLE ROLE IN FOLLICULOGENESIS.

Hiroto Uechi, Rowena Angeles and Gary D Smith*

Depts of OB/GYN, Physiology, and Urology, Reproductive Sciences Program, University of Michigan, Ann Arbor, MI. ¹

Abstract:
The catecholamines (CAT) norepinephrine (NE) and dopamine (DA), and the indolamine serotonin (5HT), are present in follicular fluid. We have demonstrated that monkey oocytes have the ability to take up DA, convert DA to NE and utilize this NE to influence granulosa cell function (PNAS 1998, 95:10990). Attempts to elucidate the physiological importance of this oocyte-derived CAT system are currently in progress using mouse oocytes. Objectives of these studies were to confirm presence of the CAT system in mouse oocytes, and investigate the influence of monoamines (MA) on in vitro folliculogenesis, ovulation and oocyte resumption of meiosis. Germinal vesicle breakdown (GVB)-incompetent and -competent oocytes were assessed for tyrosine hydroxylase (TH) and dopamine -hydroxylase (DBH) by RT-PCR, Western blot, and immunohistochemistry. While oocytes at both developmental stages did not possess TH mRNA or protein, DBH was present at mRNA and protein levels, and protein expression increased with acquisition of meiotic competence. Follicles were cultured in a modified -MEM media without (n=74) or with (n=75) a combination of 150 ng/ml NE, 150 ng/ml DA and 100 ng/ml 5HT. Follicular diameter (mean SE; m) increased during 8 days of culture from 126.1 2.5 to 394.8 21.0 and 452.9 20.5, control and treatment groups, respectively. Mean follicular diameter was significantly larger (P < 0.05) in the MA treatment group after antrum formation on days 6 and 8. Ovulation rate, after hCG administration, was not significantly different between control (66%) and MA treatment (76%). While rate of GVB was the same for control and MA treatment (87%), development to MII tended to be elevated following MA treatment (60%) compared to controls (44%), but was not significantly different (P=0.08). In summary, mouse oocytes do not contain TH, yet contain the enzyme that converts DA to NE. Inclusion of MA with follicular culture increased follicular growth after antrum formation, but did not influence ovulation or oocyte meiosis. Future experiments will focus on mechanism(s) and specific MA(s) involved in regulation of folliculogenesis. (Supported by NIH Grant HD38134).

Keywords: catecholamines, oocytes, folliculogenesis

This abstract is being presented at: 8:00 AM in session:
Follicular Development II