Ovarian 3′5′-Cyclic Adenosine Monophosphate and Prostaglandins: A Sequential Comparison of Gonadotropin-Stimulated Events in Small and Large Ovine Follicles

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Abstract
Luteinizing hormone (LH) stimulates a cascade of ovarian hormonal events that culminate in ovulation. This study was designed to investigate, in sheep, sequential changes in prostaglandin (PG) E2, PGF2 α, 6-keto-PGF1 α, and cyclic adenosine monophosphate (cAMP) in the theca, granulosa and follicular fluid of large preovulatory follicles and small nonovulatory follicles in response to LH. On d 15 postestrus, preovulatory or nonovulatory follicles were injected intrafollicularly with saline or LH. Ewes were then ovariectomized at 0, 2, 4, or 8 h postinjection. Injected follicles were excised; theca, granulosa and fluid were separated, weighed and assayed for cAMP and PG. Contents of cAMP in the theca, granulosa and fluid of preovulatory follicles increased (P < .01) 2 to 4 h after injection of LH. Increases (P < .05) in contents of PGE2 and PGF2 α in the theca and fluid of preovulatory follicles were observed between 4 and 8 h after injection of LH. The time courses of LH-induced synthesis of PGE2 and PGF2 α in preovulatory follicles were parallel. Luteinizing hormone had no effect on PGE2, PGF2 α or cAMP in any compartment of small follicles. Contents of 6-keto-PGF1 α varied with time in both theca and granulosa of large and small, saline- and LH-injected follicles. Although specific increases in cAMP and PG followed an injection of LH only in large follicles, the parallel temporal relationship of PGE2 and PGF2 α did not explain the dichotomous functions ascribed to PGE2 and PGF2 α during the periovulatory period. Copyright © 1988. American Society of Animal Science . Copyright 1988 by American Society of Animal Science

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