Persistent dominant follicle alters pattern of oviductal secretory proteins from cows at estrus

Abstract

The experimental objective was to compare synthesis of oviductal secretory proteins of dairy cows bearing a persistent dominant follicle (PDF) versus a fresh dominant follicle (FDF) at estrus. On Day 7 after synchronized estrus (Day 0), cows received an intravaginal progesterone device and injection of prostaglandin F(2α) (PGF(2α)). On Day 9, cows received an injection of a GnRH agonist (FDF group; n = 3) or received no injection (PDF group, n = 3). On Day 16, all cows received PGF(2α), and progesterone devices were removed. At slaughter on Day 18 or Day 19, oviducts ipsilateral and contralateral to the dominant follicle were divided into infundibulum, ampulla, and isthmus regions. Explants from oviductal regions were cultured in minimal essential medium supplemented with [3H]leucine for 24 h. Two- dimensional fluorographs of proteins in conditioned media were analyzed by densitometry. Rate of incorporation of [3H]leucine into macromolecules was greater in the infundibulum, ampulla, and isthmus of FDF cows (p < 0.01). Overall, intensities of radiolabeled secretory protein (P) 2 and P13 were greater for FDF than for PDF. In the ampulla, P14 was more intense for FDF while P7 was more intense for PDF. Abundance of P1 in the isthmus was greater for PDF cows. Across regions, P5, P6, P8, P9, and P11 were more intense for PDF than for FDF in the ipsilateral side. In the contralateral side, P19 was more intense for PDF than for FDF, whereas P6, P8, P9, and P11 were more intense for FDF. Differences in biosynthetic activity and in secreted oviductal proteins from cows bearing a PDF may contribute to the decrease in fertility associated with a PDF.