Submitted to: Biology of Reproduction Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: April 19, 1996
Publication Date: N/A
Profiles of IGFBPs and concentrations of steroids were evaluated in fluid from normal and persistent ovarian follicles derived from cows treated with large or small doses of progesterone (P4) for 16 d, respectively. Daily ultrasonography and concentrations of steroids in follicular fluid were used to classify follicles as: growing (G; n=8); atretic (A; n=11); growing gpersistent (GP; n=13); or atretic persistent (AP; n=10). Concentrations of 17beta- estradiol (E2) were greater (p<.05) and P4 were less (p<.05) in GP (E2:P4 ng/ml; 129.5:40.3) and G (12.7:28.2) than A (1.5:378.3) and AP (2.4:366.8) follicles. Follicles classified as GP and AP were larger (p< .05) in size than G and A follicles. Ligand blot analysis identified 6 bands of IGFBPs: IGFBP-3 (44 and 40 kDa); IGFBP-2 (34 kDa); IGFBP-5 (31 kDa); IGFBP-5 & 4 (a combination of 29 kDa form of IGFBP-5 and 28 kDa form of IGFBP-4); and IGFBP-4 (24 kDa). IGFBPs and steroids did not differ (p< .10) between A and AP follicles. IGFBPs were more abundant (p<.05) in A an AP than G and GP follicles. GP follicles had greater (p<.05) concentrations of E2 and less (p<.05) activity of IGFBP-3, -5 & 4, and -4 than G follicles. Abundance of each IGFBP was negatively correlated (p<.001) with E2 and positively correlated (p<.005) with P4. In conclusion, atresia of bovine ovarian follicles is associated with increased follicular fluid concentrations of IGFBP-4, -5 and P4 whereas persistent follicles contain greater E2 and decreased IGFBP activity when compared to normally growing follicles. Additional research is needed to determine if differences in developmental stages (i.e., size and steroid concentrations) of G and GP follicles may contribute to the present results or if decreased IGFBP activity is associated with development of persistent follicles.