A progesterone binding component in porcine ovarian follicular fluid

Abstract

Steroid hormone concentrations (progesterone, oestrone, oestradiol-17 beta) in porcine follicular fluids were measured by radioimmunoassay. In confirmation of several previous studies, as follicular maturation proceeded, the concentrations of all three steroids increased, although the relative amounts of the oestrogens decreased compared to progesterone. Analysis of fluids for steroid-binding components was undertaken using ion-exchange chromatography, gel filtration and steroid-binding assays. Evidence is presented in support of a labile binding component which exhibits high affinity and low capacity for progesterone and little or no affinity for oestadiol. Our findings are discussed in relationship to the known retention of progesterone within preovulatory follicles and to previous reports of steroid-binding components in follicular fluids.

Steroid Hormones and Prolactin in Porcine Follicular Fluid in Estrous Cycle and Early Pregnancy

“…The highest E2 concentration in FI? was found also on 20tK day of the estrpus cycle and it was similar to those found by van de Wiel et al (1983) and Fleming andMc-Gaughey (1982). However, Chang et al (1976) and Euer and Nalbandov (1977) determined higher amounts of E2 in FI?…”

“…Steroid hormones content in porcine folicular fluid has repeatedly been estimated (Chang et al, 1976;Cook et al, 1977;Euer and Nalbandov, 1977;Krzymowski et al, 1979;Ainsworth et al, 1980;Fleming andMeGaughey, 1977 andvan de Wiel et al, 1983), but not that of PRL. Only in studies on bovine (Henderson et al, 1982) and human (McNatty et al, 1974) FF, a negative correlation between P4 and PRL levels has been found.…”

Reproductive effects of immunizing heifers against androstenedione and oestradiol-17

“…Alternatively, the presence of the antibody in follicular fluid may produce even higher concentrations of follicular steroid concentrations. A possible functional significance has been attributed to binding proteins naturally found in the follicle in relation to the retention of steroids (Edwards, 1974;Fleming & McGaughey, 1982). In actively immunized animals, the increased ovarian steroid production (oestrogen or androstenedione) may keep pace with the neutralizing capacity of the antibodies, resulting in a reduced, yet still partly effective, free hormone fraction.…”

The endocrine environment of the human oocyte

“…(iii) Are there obvious sequelae for the follicle cells exposed to these large steroid levels? For example is progesterone free in follicular fluid or bound (see Fleming & McGaughey, 1982)? (iv) At follicular rupture does the 50 pg or so of progesterone and 5 pg of oestradiol (assuming a follicle with a volume of 5 ml) that is suddenly released into the peritoneal cavity have any physiological function?…”