Immunoneutralization of Inhibin and Estradiol during the Follicular Phase Of the Estrous Cycle in Cows1

Abstract

To investigate the physiological importance of inhibin and estradiol in the regulation of FSH secretion during the follicular phase of the estrous-cycle in cows, animals were passively immunized against the two hormones. Sixteen cows were divided into four equal groups and given injections of prostaglandin F2 alpha (PG) i.m. twice at 8-h intervals on Day 10 of the estrous cycle (Day 0 = day of estrus) to induce luteal regression. At 48 h after the first PG injection, each group of four cows received injections of one of the following: 100 ml castrated goat serum (control serum), 100 ml antiserum against inhibin, 100 ml antiserum against estradiol, or a combination of 100 ml inhibin antiserum and 100 ml estradiol antiserum. The LH surge occurred within 2 days after injection of the control serum or inhibin antiserum, whereas it was not detected in either of the groups passively immunized against estradiol, indicating that passive immunization against estradiol blocks a positive feedback effect of estradiol on LH secretion. There was no clear difference in basal concentrations of LH among the four groups. Injection of the inhibin antiserum resulted in a marked increase (p < 0.01) in plasma concentrations of FSH compared with values in the control group, while there were no significant changes in concentrations of plasma FSH after injection of the estradiol antiserum. Combined administration of the inhibin and estradiol antisera also produced a marked increase (p < 0.01) in plasma concentrations of FSH. The FSH response to the combined immunization was longer in duration than the FSH response to immunization with inhibin alone.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of gonadotrophin treatments on meiotic and developmental competence of oocytes in porcine primordial follicles following xenografting to nude mice

“…Grafts were recovered from the mice after infusion of FSH for 7 days (FSH-7 group) or 14 days (FSH-14 group). To inhibit a surge-like release of luteinizing hormone, 7 days after the beginning of FSH infusion the mice in the FSH-14EA group received an intraperitoneal injection of 100 ml estradiol antiserum (EA) raised in a goat (Kaneko et al 1995(Kaneko et al , 2002a, and their grafts were recovered 14 days after the beginning of FSH infusion.…”

Immunization of Goats against Inhibin Increased Follicular Development and Ovulation Rate

“…The release of FSH by the pituitary is in turn controlled by synergistic action of two of the major products of ovulatory follicles, inhibin and estradiol [6,7]. Previous findings [8][9][10] that immunoneutralization of endogenous inhibin produced a significant elevation of peripheral FSH offer evidence that inhibin is an important factor in the inhibitory regulation of FSH secretion in domestic animals as well as laboratory animals [11][12][13]. On the other hand, ultrasonographic observation of the ovary correlated with hormonal profiles demonstrated t h a t a n i n c re a s e i n p l a s m a F S H p r ec e d e d emergence of each follicular wave [14][15][16][17] and a decrease in FSH was coincident with functional selection of follicles [15,18], suggesting that the fluctuation in peripheral FSH levels is a trigger for growth, selection, and atresia of follicles.…”

“…The release of FSH by the pituitary is in turn controlled by synergistic action of two of the major products of ovulatory follicles, inhibin and estradiol [6,7]. Previous findings [8][9][10] that immunoneutralization of endogenous inhibin produced a significant elevation of peripheral FSH offer evidence that inhibin is an important factor in the inhibitory regulation of FSH secretion in domestic animals as well as laboratory animals [11][12][13]. On the other hand, ultrasonographic observation of the ovary…”

Cyclic changes in messenger RNAs encoding inhibin/activin subunits in the ovary of the golden hamster (Mesocricetus auratus)

“…Although activins were initially isolated as gonadal peptides that stimulate FSH secretion (de Jong 1988, Ying 1988, they are now known to be multifunctional growth factors that are very important for vertebrate development and other physiological events , Hillier & Miro 1993, Findlay et al 2001. Inhibins are known to be major FSH-suppressing factors in the female in mammals (Rivier et al 1986, Culler & Negro-Vilar 1989, Kaneko et al 1995, Kishi et al 1999, Medan et al 2003 and are important for determining species-specific ovulation rate . They are mainly expressed in granulosa cells of the ovary in adult cyclic females of various mammals, such as rats (Merchenthaler et al 1987, Meunier et al 1988, golden hamsters (Kishi et al 2002), Siberian hamsters (Phodopus sungorus) (Kenny et al 2002a,b), sheep (Engelhardt et al 1993), pigs (Rokukawa et al 1986), cows (Rokukawa et al 1986), monkeys (Schwall et al 1990) and humans (Merchenthaler et al 1987).…”