Submission Number: SHY-4-15-2

Abstract Number: 490

GLUCOCORTICOID MODULATES ESTROGEN (E) AND PROGESTERONE (P)INDUCED TRANSFORMINGGROWTH FACTOR RECEPTOR (TR) mRNA EXPRESSION IN HAMSTER PREANTRAL FOLLICLES.

Shyamal K Roy ^1,2 and Laura Albee ¹

Olson Center for Women's Health, Dept. of Ob/GYN, University of Nebraska Medical Center, Omaha, NE 68198-4515 ¹
Dept. of Physiology and Biophysics, University of Nebraska Medical Center, Omaha, NE 68198-4515 ²

Abstract:
Dexamethasone attenuates P and Einduced ovarian TGF receptors (TR) typeI andII mRNA expression in vivo. Because, both follicles and interstitial cells contribute to ovarian RNA, the objectives of the present studies were to determine whether [1] E, P and FSH directly induced follicular TR mRNA expression, and [2] glucocorticoid inhibited the effect of E and P in vitro. Preantral follicles at stages 2 (S2) through 6 (S6), and early antral follicles at stage 7 (S7) were collected from hamsters at D4:0900h, and cultured in DMEM containing TS^{MISSING CHARACTER ENTITY: plus} and 0.1 mg/ml insulin in the presence of 100 ng/ml each of E, P, FSH or EMISSING CHARACTER ENTITY: plus hydrocortisone (0.01, 0.1 and 1M) for 24h at 37C under 5% CO₂ in air. TRI and TRII mRNA levels were measured by semiquantitative RTPCR, normalized against hamster ribosomal protein, S4, mRNA, and the results were expressed as fold change relative to control.

At least twofold induction of TRI mRNA by E and P was noted for preantral follicles at S3 and onwards. Whereas EMISSING CHARACTER ENTITY: plusP induced TRI mRNA for S2 and S7, the combination eliminated the effect of each steroid alone on other stages, suggesting that the magnitude of steroidinduced intracellular signaling may ultimately determine TRI mRNA levels in a stagespecific manner. FSH increased TRI mRNA from S5 and onwards, indicating the onset of functional differentiation in the granulosa cells. Whereas 0.01 and 0.1 M of hydrocortisone significantly attenuated the E effect from S3 and onwards, 1 M dose was stimulatory for S2. In contrast, none of the steroids had any significant effect on TRII mRNA levels, except a lowering trend.

These results suggest that follicular TR mRNA levels are differentially influenced by E and P. Whereas TRI mRNA levels influenced directly by follicular steroids, the levels of TRII mRNA remains unaffected. Hydrocortisone may influence TRI mRNA expression by inhibiting transcription as reported for kidney cell lines. Moreover, because TRII mRNA levels can be as much as 37fold more than TRI depending on the stage of preantral follicles, and both receptors are essential for TGF action, critical regulation of TRI mRNA, hence the receptors, may adequately modulates TGF effect during preantral follicular development. .

Keywords: TGF-beta receptor, preantral follicles, estrogen, progesterone, glucocorticoid, hamster, ovary

This abstract is being presented at: 8:00 AM in session:
Growth Factors II