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(193) THE EFFECTS OF PROGESTERONE OR PROGESTERONE PLUS ESTROGEN TREATMENT ON OVARIAN TISSUE REMODELING ENZYMES, MMP-2 AND TIMP-1. Desvousges, Andria1, Sharp, Dan1, Steidl, Elizabeth1, Muise, Victoria1, 1 University of Florida, Gainesville, FL, USA ABSTRACT- We have shown that matrix metalloproteinase-2 (MMP-2) and its inhibitor, TIMP-1, increase with impending ovulation in mares, and that hCG administration increases MMP-2 and TIMP-1 in follicular fluid (FF). To test the hypothesis that gonadotropins are critical for tissue remodeling in horses, 8 cycling mares randomly received: control vehicle (CV; n=3), progesterone, (P4; 150 mg/day, n=3) or progesterone plus estradiol (P+E; 150 mg & 10 mg/day, n=2) beginning at the time of prostaglandin F2 KEY WORDS: ovulation, gonadotropin, tissue remodeling, mare |
(PGF)-induced luteolysis and continuing until first detected 30 mm follicle. At 30 mm follicle, mares were ovariectomized, FF from dominant follicle collected, and follicle wall pieces prepared for in vitro culture in phenol-free MEM at 370 C in of N:CO2:O2 (50:3:47%) for 24 hr with media changes at 4, 9, 12 and 24 hr. hCG (10 IU/ml and cyclic MMP-2 inhibitor, 50nm/ml) were added to cultures to test stimulation and inhibition of in vitro MMP-2 production, respectively. FF and incubation media were analyzed for MMP-2 and TIMP-1 by gelatin zymography and reverse gelatin zymography, respectively. Data were analyzed by analysis of variance, with main effects of in vivo treatment, in vitro treatment, and time, with attention to all interactions. MMP-2 was significantly decreased in FF of P+E-treated mares, but not CV or P4-treated mares (p<.0.01). MMP-2 increased (p<0.002) with time of culture, however, mean MMP-2 production was significantly (p<0.001) reduced when follicle wall was derived from P4 or P+E-treated mares. hCG treatment increased (p<0.001) MMP-2 in culture regardless of mare treatment, and cyclic inhibitor significantly (p<0.001) reduced in vitro MMP-2 production in all groups. TIMP-1 showed little change with time or a general decline in production, which reflected a tendency (p<0.06) for cyclic inhibitor to reduce TIMP-1 production in vitro. Reduction in Luteinizing Hormone (LH) by P4 treatment significantly reduced MMP-2 production in vitro and P+E treatment, which blocked both LH and Follicle Stimulating Hormone (FSH) further reduced both MMP-2 and TIMP-1. These data suggest a critical need for gonadotropins for tissue remodeling for ovulation.