Abstract
The effect of perfusion of hCG, PGF2α, vasoactive peptides, and Ringer's solution (control) on the ovaries of mares (Percheron, Breton and crossbred) during early and functional luteal phases of the ovarian cycle was studied using an in vitro microdialysis system. There was no increase in P4 secretion as a result of the perfusion of 10 IU or 100 IU of hCG during the early or functional luteal phase. But both the levels of hCG significantly increased PGF2α release, compared to the control, during early luteal phase (p<0.05). During functional luteal phase, 100 IU hCG caused significantly higher secretion of PGF2α than 10 IU hCG or the control (p<0.05). P4 release was significantly higher than in the control (p<0.05) with PGF2α perfusion in both the early and the functional luteal phases. Vasoactive peptides (angiotensin-Ⅱ, endothelin-Ⅰ and atrial natriuretic peptide) did not cause a significant difference in P4 release during the early or the functional luteal phase. However, PGF2α release was significantly increased compared to the control (p<0.05) in both phases. These results suggest that hCG and vasoactive peptides had a profound effect on PGF2α release but did not stimulate P4 secretion during the early or the functional luteal phase in equines.
