Identification, purification and immunohistochemical detection of the inhibitor from porcine ovarian follicular fluid to compensatory ovarian hypertrophy in mice

Intraovarian control of selective follicular growth and induction of oocyte maturation in mammals

In newborn mammals, most of the germ cell population rests in a pool of quiescent small follicles in the ovaries. Regularly throughout adulthood, a small percentage of these oocytes and follicles grows to a certain stage of development and then either degenerates or matures and ovulates. This entire process is under both exogenous and endogenous control. Recent work, including my laboratory's, has clarified that cytokines and glycosaminoglycans are involved as exogenous and endogenous factors in ovarian follicular development, atresia, and maturation in mammals. The present article describes our contribution regarding the cytokines and ovarian glycosaminoglycans that act as intraovarian regulators of follicular development and oogenesis, including oocyte maturation, in mammals.

Control of FSH, follicular development and estrus synchronization in the mare with steroid-free follicular fluid

Twenty-two pony mares were used in a project designed to determine the effectiveness of different treatments in controlling FSH, follicular development and synchronization of estrus and ovulation. Mares in Group 1 (n=8) received daily oral altrenogest (0.044 mg/kg); those in Group 2 (n=7) received daily altrenogest (0.044 g/kg) and, during the last 4 days of treatment they received steroid-free follicular fluid, (15 cc) intravenously (I.V.) two times a day; Mares in Group 3 (n=7) received daily intramuscular (I.M.) injections of progesterone (80 mg) and estradiol valerate (7 mg). All treatments lasted for 10 days, at the end of which prostaglandin (PgF(2)alpha, 10 mg) was administered. Sexual behavior, follicular development and FSH concentrations were monitor daily. Concentrations of FSH in Group 2 mares, were not significantly different (P>0.05) from those of Group 1 until the mares in Group 2 were treated with follicular fluid (P<0.05). Concentrations of FSH in Group 3 mares, were significantly lower than those of Groups 1 and 2 (P<0.05) until the mares in Group 2 were treated with steroid-free follicular fluid. At this point there was no significant difference between groups 2 and 3 (P>0.05). Steroid-free follicular fluid appears to induce atresia in larger follicles (>11 mm), and the initiation of new follicular wave. The combination of progesterone and estradiol valerate appears to delay follicular growth and not to induce atresia, since larger follicles (>11 mm) continued to grow after treatment. Both treatments (groups 2 and 3) resulted in ovulations within 5 days period. The treatment in Group 1 did not have any effect on FSH or follicular development and ovulations were dispersed through a 9-day period. We concluded that steroid-free follicular fluid offers a new possibility to synchronize ovulation in the mare by controlling FSH and follicular development.

Inhibition and subsequent rebound of FSH secretion following treatment with bovine follicular fluid in the ewe

Plasma concentrations of gonadotropins were examined after treatment of ewes with bovine follicular fluid (FF) in four experiments. Mean concentrations of FSH were significantly decreased by FF treatment. The FSH depression appeared to continue throughout the length of treatment when the duration of treatment was 2-4 days. However, in an experiment in which the treatment period was 8 days, mean concentrations of FSH initially declined and then returned to control levels during the last 4 days of treatment. In all experiments, a rebound in FSH concentrations was found 24-36 h after cessation of FF treatment. The magnitude of this rebound appeared to be proportional to the degree of FSH suppression during FF treatment.

The use of affinity matrices in the purification of inhibin from bovine follicular fluid

The protein associated with inhibin-like activity in bovine follicular fluid was purified 80- to 120-fold after successive adsorptions on different affinity matrices, i.e. Matrex gel red A, phenyl sepharose, omega-aminohexyl agarose and concanavalin-A sepharose. Partial characterization of the active protein resulted in the conclusion that inhibin from bovine follicular fluid is a hydrophobic glycoprotein with an apparent molecular weight between 60 000 and 70 000 daltons. An antiserum, raised against an 80-fold purified preparation, prevented the inhibin-like action of bovine follicular fluid on pituitary cells in vitro.

Effect of inhibin-like substance isolated from porcine follicular fluid on the follicle-stimulating hormone (FSH) level in mouse serum and on FSH binding to porcine granulosa cells

An inhibin-like substance, a follicle-stimulating hormone (FSH) inhibitor, was isolated from porcine follicular fluid and purified. Serum FSH levels of unilaterally ovariectomized mice which received injections of the inhibitor were lower than those of unilaterally ovariectomized mice which received injections of saline. The inhibitor also suppressed FSH binding to granulosa cells in vitro. These results suggest that this protein is an FSH inhibitor and that it has two modes of action: suppression of FSH levels in serum and suppression of FSH binding to granulosa cells.