Hisashi Kishi

Effects of passive immunization against inhibin on ovulation rate and embryo recovery in holstein heifers

The effects of acute neutralization of endogenous inhibin on ovulation rate and circulating FSH levels were investigated. Nine or ten days after estrus, 5 heifers were given a single injection of 75 ml iv inhibin antiserum produced in a castrated male goat, while another 5 were given the same amount of a castrated male goat serum. All heifers were given injections of PGF2alpha im at 48 h and 60 h after the serum injection. Those exhibiting an estrus were artificially inseminated with frozen-thawed semen. Seven or eight days after the insemination, ova or embryos were collected using a non-surgical method. Administration of inhibin antiserum resulted in a significant increase in the number of medium-sized follicles compared with the number in the control animals. The number of large follicles in the inhibin-neutralized animals was 4.8 +/- 2.4 (mean +/- SEM; n = 5) on the day of estrus, while there was a single large follicles in the ovaries of control animals. Seven or eight days after estrus, 3 to 16 ova or embryos were recovered from 4 of 5 animals, and 64 % of the total ova/embryos were transferable. Administration of inhibin antiserum produced a significant increase in the concentrations of plasma FSH from 12 to 72 h after the serum injection compared with the levels in the control animals (P < 0.05). After the onset of estrus, preovulatory LH and FSH surges were noted in inhibin-neutralized animals and magnitude of the rise in each hormone was similar to the control animals. The present study demonstrates that a single injection of the inhibin antiserum induces multiple ovulations probably by enhancing FSH secretion, and that recovery of embryos is equal to that observation after an ordinary FSH treatment.

Role of inhibin in the regulation of FSH secretion and folliculogenesis in cows

Abstract This review focuses on the role of inhibin and oestradiol in the hormonal regulation of ovarian folliculogenesis during the oestrous cycle in cows and other domestic animals, using data from the cow, sheep, pig, horse, rat and hamster. The evidence reviewed confirms the role of inhibin as a chemical signal of the number of growing follicles in the ovary to the pituitary gland to reduce the secretion of follicle stimulating hormone (FSH) to a level which maintains the species-specific number of ovulations. It is argued that ovarian inhibin may be the most important hormone for determining the species-specific number of ovulations in both single and multiple ovulatory species. On the other hand, evidence presented in the review also confirms the importance of ovarian oestradiol acting as a chemical signal to indicate the maturity of growing follicles to the hypothalamo-pituitary system. This induces the preovulatory luteinising hormone (LH) surge to cause ovulation.

Superovulation of holstein heifers by a single subcutaneous injection of FSH dissolved in polyvinylpyrrolidone

This study was undertaken to determine whether a single injection of porcine FSH (pFSH) would induce a superovulatory response in cattle. Holstein heifers were given a single injection of pFSH (30 mg, s.c.) dissolved in saline (Group 1, n = 5); 50% polyvinylpyrrolidone (PVP; Group 2, n = 5); or 25% PVP (Group 3, n = 4). Group-4 heifers (n = 5) were given multiple intramuscular injections of pFSH every 12 h for 3 d at decreasing doses, for a total of 30 mg. All animals received a single injection of 750 microg PGF2 alpha 48 h after the initiation of pFSH treatment. Animals exhibiting estrus were artificially inseminated twice throughout estrus. Ova and embryos were recovered nonsurgically. Ovaries were examined by transrectal ultrasonography or by palpation per rectum on Day 7 or 8 of estrus. Plasma concentrations of pFSH, bovine FSH progesterone, estradiol-17 beta and inhibin were determined by specific radioimmunoassays. The number of corpora lutea (CL) and the numbers of total and transferable embryos which were detected and recovered in Groups 2 and 3 were equivalent to the numbers detected and recovered in Group 4. In Group 1, however, only 1 of 5 animals ovulated even a single oocyte. The present study demonstrated that only a single injection of pFSH dissolved in PVP was capable of inducing a superovulatory response by maintaining a high plasma FSH concentration to allow for the recovery of a sufficient number of embryos for transplantation.

Effect of active immunization of cattle against inhibin on ovarian follicular development and ultrasound-guided transvaginal follicular aspiration

Abstract The effects of active immunization of cattle against inhibin on ovarian follicular development and ultrasound-guided transvaginal follicular aspiration were determined. Six Multiparous Japanese Black were actively immunized with a synthetic peptide replica of the amino acid sequence from 1 to 26 (numbering from the N-terminal end) position of the α-subunit of porcine inhibin (pINH) conjugated with rabbit serum albumin (RSA) using Freunds complete adjuvant. At 6, 10 and 14 wk after the primary injection, booster injections of the peptide were given. As controls, 6 Japanese Black received rabbit serum albumin as described above. Blood samples were taken at 0, 2, 6 wk and once a week from 10 to 17 wk after the primary injection to measure antibody titer. The changes in the numbers of recruited follicles of the 3 size categories (small, 2 to 3 mm; medium, 4 to 9 mm and large, ≥ 10 mm) and aspirated oocytes were examined once a week from 10 to 17 wk using ultrasound scanning. Antibody titers increased after the first booster in all immunized cattle. In comparison with controls, inhibin-immunized cattle had more small, medium and large follicles during the ultrasound scanning (16.0 ± 1.8, 4.0 ± 0.6 and 2.2 ± 0.3 versus 9.1 ± 0.5, 1.7 ± 0.2 and 1.1 ± 0.1, respectively; P

Tumor necrosis factor-α and its receptor in the corpus luteum of pregnant cows.

The objective of this study was to investigate the presence of tumor necrosis factor (TNF)‐α mRNA and TNF‐α receptors in the bovine corpus luteum (CL) during the gestation period. TNF‐α mRNA and TNF‐α receptors were determined on bovine CL from pregnant cows at three stages: trimester I (fetal crown‐rump length; 6–20 cm), trimester II (25–45 cm) and trimester III (50–80 cm). TNF‐α mRNA was detected by an RT‐PCR analysis in the CL of all stages of gestation. A Scatchard analysis revealed the presence of a high‐affinity binding site (Kd; 5.1–6.9 nM) in the CL membranes collected at each stage of gestation. Furthermore, the concentrations of TNF‐α receptors in the CL of trimesters I (24.0 ± 1.95 pmol/mg protein) and III (21.6 ± 2.39 pmol/mg protein) of gestation were significantly higher than the concentration in trimester II (14.9 ± 2.07 pmol/mg protein) (P < 0.05). These results indicate that TNF‐α is locally produced and that TNF‐α receptors are present in bovine CL during the gestation period, and suggest that TNF‐α plays one or more roles as a paracrine factor in regulating bovine CL function during the entire gestation period. Mol. Reprod. Dev. 55:406–411, 2000.

Changes in Expression of Inhibin Subunits in the Cyclic Golden Hamster (Mesocricetus auratus) and the Regulation of Inhibin α Subunit Production by Luteinizing Hormone

In the present study, changes in localization of each inhibin subunit in the ovary were investigated during the estrous cycle of the golden hamster. The effect of LH surge on changes in localization in inhibin α subunit in the ovary was also investigated. Inhibin α subunit was localized in granulosa cells of various stages of follicles throughout the estrous cycle. Inhibin α subunit was also present in numerous interstitial cells on days 1 and 2 (day 1 = day of ovulation), but the number of positive interstitial cells was fewer on days 3 and almost disappeared on day 4 of the estrous cycle. Newly formed luteal cells were also positive for inhibin α subunit on days 1 and 2. On the other hand, positive reactions for inhibin βA and βB subunits were only present in the granulosa cells of healthy antral follicles. However, a positive reaction for inhibin βB subunit in peripheral mural granulosa cells disappeared on days 3 and 4 of the estrous cycle. Treatment with LHRH-AS at 1100 h on day 4 completely blocked the luteinizing hormone (LH) surge and ovulation, although relatively high concentrations of plasma follicle-stimulating hormone (FSH) were maintained throughout the experiment. There were few positive reactions for inhibin α subunit in theca and interstitial cells 24 hr after LHRH-AS injection. The effect of LHRH-AS treatment was blocked by a single injection of 10 IU human chorionic gonadotropin. These results suggest that the major source of dimeric inhibin in the cyclic hamster was granulosa cells of healthy antral follicles. Different distribution pattern of inhibin βA from βB subunits in large antral follicles on days 3 and 4 of the estrous cycle suggests different secretion patterns of inhibin A from B on these days. Furthermore, the LH surge may be an important factor to induce production of inhibin α subunit in interstitial cells of the cyclic hamster.

Regulations of gonadotropin secretion by circulating inhibin, estradiol, and progesterone in cyclic hamsters

The physiological importance of gonadal hormones in feedback control of gonadotropin secretion during the estrous cycle in golden hamsters was investigated with immunoneutralization methods. Anti-inhibin serum (inhibin-AS) treatment always induced a drastic increase in follicle-stimulating hormone (FSH) secretion and occasionally raised luteinizing hormone (LH) secretion. Anti-estradiol-17β serum (estradiol-AS) treatment increased LH secretion typically. Although estradiol-AS elevated FSH secretion occasionally, the elevation was much less than that by inhibin-AS. Plasma FSH reached ovariectomized levels by a synergistic effect of both antisera. Elevated plasma LH with both antisera was much less pronounced than in ovariectomized animals. Plasma LH increased dramatically to the levels in the ovariectomized group when antibody against progesterone (progesterone-AB) was given together with inhibin-AS and estradiol-AS, although progesterone-monoclonal antibody alone did not alter plasma gonadotropin levels. These results indicate that in hamsters FSH secretion is mainly regulated by inhibin and LH secretion is regulated by estradiol-17β and progesterone during the estrous cycle.The physiological importance of gonadal hormones in feedback control of gonadotropin secretion during the estrous cycle in golden hamsters was investigated with immunoneutralization methods. Anti-inhibin serum (inhibin-AS) treatment always induced a drastic increase in follicle-stimulating hormone (FSH) secretion and occasionally raised luteinizing hormone (LH) secretion. Anti-estradiol-17beta serum (estradiol-AS) treatment increased LH secretion typically. Although estradiol-AS elevated FSH secretion occasionally, the elevation was much less than that by inhibin-AS. Plasma FSH reached ovariectomized levels by a synergistic effect of both antisera. Elevated plasma LH with both antisera was much less pronounced than in ovariectomized animals. Plasma LH increased dramatically to the levels in the ovariectomized group when antibody against progesterone (progesterone-AB) was given together with inhibin-AS and estradiol-AS, although progesterone-monoclonal antibody alone did not alter plasma gonadotropin levels. These results indicate that in hamsters FSH secretion is mainly regulated by inhibin and LH secretion is regulated by estradiol-17beta and progesterone during the estrous cycle.