Immunization Against an Inhibin Subunit Produced by Recombinant Dna Techniques Results in Increased Ovulation Rate in Sheep

Abstract

Seven Merino-Border Leicester cross-bred ewes were immunized with a purified fusion protein, produced by recombinant DNA methods, of the alpha subunit of bovine inhibin. Four animals were immunized with the fusion protein alone and three with a conjugate made by coupling the fusion protein to keyhole limpet haemocyanin (KLH) using glutaraldehyde. Each animal received four injections of the fusion protein over 93 days. The animals were synchronized using progestagen sponges and subjected to laparoscopy for the determination of ovulation rates in two consecutive cycles (days 115 and 135). The immunized animals had overall mean ovulation rates for each cycle of 3.4 and 3.4 which was significantly (P less than 0.001) above the rates of 1.1 and 1.4 determined for the controls, which had either received no treatment (n = 5) or had been immunized with 300 micrograms KLH (n = 4). Analysis of antisera taken on day 115 showed significant fusion protein antibodies and iodinated inhibin-binding capacity in the test but not control groups. Furthermore, antisera to the fusion protein in four out of seven ewes neutralized the inhibin bioactivity of ovine follicular fluid in an in-vitro bioassay. These data demonstrate that neutralization of inhibin can be effected by immunization with bovine inhibin alpha subunit and that such immunization results in increased ovulation rates as predicted from the biological role of inhibin as a suppressor of FSH.

Effects of Active Immunization with Inhibin α Subunit on Reproductive Characteristics of Turkey Hens1

“…Active immunization against INH neutralizes endogenous INH and increases the ovulation rate in mammals [6,7,10,[37][38][39]. The results of the present study showed no significant difference in egg production between birds that were actively immunized against INH and control hens, even though immunization significantly increased the number of preovulatory yellow follicles and significantly increased FSH␤ subunit mRNA content in the anterior pituitary.…”

Ovarian Response and Hormonal Profiles in Heifers After Immunization and Re-immunization Against Inhibin .ALPHA.-Subunit.

“…The α-subunit of ovine inhibin produced in E. coli the by the recombinant DNA method [17] was used as an immunogen. Immunizations were given at a dose of 1 ml of the immunogen (125 µg/ml) in Montanide 888:Marcol 52 (1:9) each time.…”

An Update on the Roles of Inhibin, Activin, and Follistatin as Local Regulators of Folliculogenesis1

“…On the other hand, nondominant follicles would not have these survival mechanisms and would therefore be destined to become atretic. With respect to the potential paracrine role of inhibin on theca androgen production, it is worth mentioning that immunization of animals against inhibin-which produces antibodies that recognize biologically active forms of inhibin-causes an increase in ovulation rate [19]. This suggests that either an action of inhibin on theca cells in vivo is not an absolute requirement for normal follicular development and ovulation or that the inhibin antibodies are not able to compromise an action of inhibin on the theca.…”