J. Anim Sci.
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J. Anim Sci. 1984. 58:955-962.
© 1984 American Society of Animal Science
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Effect of Prostaglandin F2{alpha} on the Adenylate Cyclase and Phosphodiesterase Activity of Ovine Corpora Lutea1

L. Sp. Agudo2, W. L. Zahler3 and M.F. Smith2

University of Missouri, Columbia 65211

Abstract

The objective of the present study was to determine the temporal relationships among luteal adenylate cyclase activity, luteal phosphodiesterase activity, luteal progesterone concentration and plasma progesterone concentration during prostaglandin F2{alpha} (PGF2{alpha})-induced luteolysis in ewes. Corpora lutea (CL) were removed from cycling ewes on d 9 (d 0 = first day of estrus) at 0, 2, 4, 6, 12 and 24 h (seven to eight ewes/group) after PGF2{alpha} administration (im). Jugular blood samples were collected at the time of enucleation of CL and analyzed for progesterone. Plasma and luteal progesterone concentrations were decreased (P<.05) by 4 and 12 h after PGF2{alpha} injection, respectively. Basal adenylate cyclase, luteinizing hormone (LH)-activated adenylate cyclase, guanylylimido-diphosphate [Gpp(NH)p] -activated adenylate cyclase and LH plus Gpp(NH)p-activated adenylate cyclase activities were decreased (P<.05) by 2 h after PGF2{alpha} injection. The decrease in adenylate cyclase activity paralleled the decrease in plasma progesterone concentration over time. Luteinizing hormone stimulated (P<.05) adenylate cyclase activity relative to basal activity at 0, 2, 12 and 24 h post-PGF2{alpha}; whereas, Gpp(NH)p stimulated (P<.01) adenylate cyclase activity relative to basal activity at each time point. In contrast to the decrease in adenylate cyclase activity, phosphodiesterase activity was increased (P<.05) at 2 and 4 h post-PGF2{alpha}. These results suggest that a decrease in adenylate cyclase activity coupled with an increase in phosphodiesterase activity may decrease the intracellular adenosine 3',5' cyclic monophosphate (cAMP) concentration. This decrease in the concentration of intracellular cAMP may be one of the early events resulting in lowered progesterone concentrations during PGF2a-induced luteolysis in ewes.

Footnotes

1 Contribution from the Missouri Agr. Exp. Sta. Journal Ser. No. 9348.

2 Dept. of Anim. Sci.

3 Dept. of Biochem.






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