Immunization against inhibin enhances both embryo quantity and quality in Holstein heifers after superovulation and insemination with sex-sorted semen

Factors affecting superovulation induction in goats (Capra hericus): An analysis of various approaches

Goats are generally called a "poor man's cow" because they not only provide meat and milk but also other assistance to their owners, including skins for leather production and their waste, which can be used as compost for fertilizer. Multiple ovulation and embryo transfer (MOET) is an important process in embryo biotechnology, as it increases the contribution of superior female goats to breeding operations. The field of assisted reproductive biotechnologies has seen notable progress. However, unlike in cattle, the standard use of superovulation and other reproductive biotechnologies has not been widely implemented for goats. Multiple intrinsic and extrinsic factors can alter the superovulatory response, significantly restricting the practicability of MOET technology. The use of techniques to induce superovulation is a crucial step in embryo transfer (ET), as it accelerates the propagation of animals with superior genetics for desirable traits. Furthermore, the conventional superovulation techniques based on numerous injections are not appropriate for animals and are labor-intensive as well as expensive. Different approaches and alternatives have been applied to obtain the maximum ovarian response, including immunization against inhibin and the day-0 protocol for the synchronization of the first follicular wave. While there are several studies available in the literature on superovulation in cattle, research on simplified superovulation in goats is limited; only a few studies have been conducted on this topic. This review describes the various treatments with gonadotropin that are used for inducing superovulation in various dairy goat breeds worldwide. The outcomes of these treatments, in terms of ovulation rate and recovery of transferrable embryos, are also discussed. Furthermore, this review also covers the recovery of oocytes through repeated superovulation from the same female goat that is used for somatic cell nuclear transfer (SCNT).

Rectifying cow infertility under heat stress by immunization against inhibin and supplementation of progesterone

This study was undertaken for the development of novel techniques that are based on immunoneutralization of inhibin bioactivity to improve Holstein cow fertility. A series of 4 experiments were carried out on 2 farms that were located in subtropical or temperate regions, to test the effects of immunization against inhibin alpha subunit on cow fertility under varying degrees of heat stress conditions. Though immunization against inhibin alone improved conception rate (CR) after TAI moderately in cows under mild heat stress conditions, the treatment plus progesterone supplementation substantially enhanced CR in the range of 25 to 35 percentages from severe heat stress to comfortable weather conditions. There existed an additive effect between immunization against inhibin and progesterone supplementation that maximally enhanced CR. Further, immunization against inhibin increased both FSH and activin A concentrations in blood during both follicular and luteal phases. It also significantly increased blood concentrations of E2 in the follicular phase but decreased P4 concentrations during the early pregnancy. However, interferon-tau concentrations in blood around the time of pregnancy recognition were doubled in the inhibin immunized cows. In conclusion, immunization against inhibin plus P4 treatment enhances ovarian follicle and the subsequent early embryo developments that help to greatly improve the fertility of Holstein dairy cows.

How neuroactive factors mediates immune responses during pregnancy: An interdisciplinary view

Pregnancy, from insemination to parturition, is a highly complex but well-orchestrated process that requires various organs and systems to participate. Immune system and neuroendocrine system are important regulators in healthy pregnancy. Dozens of neuroactive factors have been detected in human placenta, whether they are locally secreted or circulated. Among them, some are vividly studied such as corticotropin-releasing hormone (CRH), human chorionic gonadotropin (hCG), transforming growth factor-β (TGF-β), progesterone and estrogens, while others are relatively lack of research. Though the neuroendocrine-immune interactions are demonstrated in some diseases for decades, the roles of neuroactive factors in immune system and lymphocytes during pregnancy are not fully elucidated. This review aims to provide an interdisciplinary view on how the neuroendocrine system mediate immune system during pregnancy process.

Immunization Against Inhibin Promotes Fertility in Cattle: A Meta-Analysis and Quality Assessment

Superovulation and embryo transfer techniques are important methods in cattle breeding. Combined with traditional superovulation protocols, immunization against inhibin can further improve follicular development and embryo yield. The aim of this study is to determine the efficacy of immunization against inhibin in improving the fertility of cattle through meta-analysis and to provide better clinical veterinary practice guidance. Three English databases (PubMed, EMBASE, Web of Science) were searched for research articles of immunizations against inhibin influence on cattle fertility. Literature screening, data extraction, and meta-analysis were conducted in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. In addition, the Systematic Review Center for Laboratory animal Experimentation (SYRCLE) risk-of-bias (RoB) tool was used to assess the risk of bias of the included animal studies. Potentially relevant studies (317) were identified, and finally 14 eligible studies (all in English) were included. The results of meta-analysis revealed that immunization against inhibin has significant effects on improving the number of ovulations [mean difference (MD) = 0.44, 95% confidence interval (CI) = (0.31, 0.56)], embryos and unfertilized ova [MD = 4.51, 95% CI = (2.28, 6.74)], follicles of the three size categories, the incidence of multiple ovulations [OR = 22.50, 95% CI = (8.13, 62.27)], and the conception rate [OR = 2.36, 95% CI = (1.26, 4.40)]. Moreover, it improved the production of embryos [grades 1 embryos: MD = 3.84, (3.54, 4.15); grade 2 embryos: MD = -0.73, (-0.89, -0.57); grade 3 embryos: MD = -0.50, (-0.75, -0.25); degenerated embryos: MD = 1.16, (-0.51, 2.82); transferable embryos: MD = 2.67, (2.03, 3.31)] and the number of corpora lutea [MD = 1.25, 95% CI = (0.79, 1.71)]. In the above indicators, the differences between the two groups were statistically significant (all p < 0.0001). Additionally, according to the quality evaluation results, the risk of bias in the included studies is relatively high. The quality evaluation of the results of the included studies showed that the risk of bias mainly concentrated in the selective, performance, detection, and reporting of bias aspects.

Effects of immunization against inhibin α-subunit on ovarian structures, pregnancy rate, embryonic and fetal losses, and prolificacy rate in goats where estrus was induced during the non-breeding season

The objectives of the study were to determine the dose-dependent effects of active immunization against inhibin α-subunit (AIINHA) on ovarian dynamics, concentrations of progesterone (P₄), pregnancy rate (PR), embryonic and fetal losses (EFL), and prolificacy during the non-breeding season when there was imposing of a progestin-based treatment regimen to induce estrus in Beetal goats. Goats (n = 30) were randomly assigned into following groups: 1) saline (G-CON-0 mg; n = 10), 2) small dose (G-AIINHA-0.5 mg; n = 10), and 3) large dose (G-AIINHA-1 mg; n = 10). The primary administration of inhibin immunogen was administered at Day -48, followed by another administration at Day -20, and subsequently there was induction of estrus using a progestin based treatment regimen that included a single administration of progestin-containing sponge and PGF_2α at Day -8. The sponge was removed, and GnRH was administered at Day -3 followed by breeding (Day 0) at standing estrus. Results indicated mean diameter of the follicles, size of pre-ovulatory follicles and corpora lutea, and post-breeding P₄ concentrations were greater (P < 0.05) in the goat does of the G-AIINHA-0.5 than G-CON-0 group. The PR, and EFL, however, did not differ (P> 0.05) among groups, whereas prolificacy rate was greater (P = 0.04) in goat does of the G-AIINHA-0.5 than G-CON-0 groups. The data from this study indicate G-AIINHA-0.5 is the recommended dose of inhibin immunogen to enhance the reproductive performance during non-breeding season in Beetal goats when estrus is induced using a progestin-based treatment regimen.

Improving ovulation in gilts using anti-inhibin serum treatment combined with fixed-time artificial insemination

For successful batch farrowing, porcine oestrus and ovulation must be synchronized using fixed-time artificial insemination (FTAI). However, exogenous gonadotropins, which are currently used in FTAI, negatively affect gilt ovulation. Here, we aimed to improve sexually mature gilt superovulation efficiency using passive immunization against inhibin during FTAI. Altrenogest-treated gilts were challenged with 10 ml anti-inhibin serum (AIS group, n = 6), 1,000 IU pregnant mare serum gonadotropin (PMSG group, n = 6), or 10 ml goat serum (control group, n = 6). Gilts in the AIS and PMSG groups were inseminated according to the FTAI protocol, and gilts in the control group were inseminated during natural oestrus. When PMSG was replaced by AIS during FTAI of gilts, ovulation rate and embryos recovered were significantly greater in the AIS group as compared to the other two groups (p < .05). Especially the average number of 6-8-cell embryos in the AIS group was significantly higher than that in the PMSG group (p < .01). Moreover, the blastocyst number in the AIS group was significantly higher than that in the PMSG group and the control group (p < .05). But there was no significant difference in the blastocyst number between the PMSG group and the control group (p > .05). Besides, plasma levels of estradiol-β (E2) and progesterone (P4) were significantly greater in the AIS group as compared to the other two groups on Day 23 and D 27, respectively (p < .01). In summary, we devised an improved high-yield FTAI protocol for sexually mature gilts using AIS; this protocol had a greater superovulation efficiency than the FTAI using PMSG.

Conception Rate and Reproductive Hormone Secretion in Holstein Cows Immunized against Inhibin and Subjected to the Ovsynch Protocol

Simple Summary

In recent decades, conception rates in lactating dairy cows have dramatically decreased, and improving the conception rate has become a major challenge in dairy cow reproduction. Various Ovsynch protocols have been developed to aid in the resumption of ovarian follicular activity for timely breeding in post-partum cows. However, the effect of Ovsynch protocols on improving the conception rate is unsatisfactory. In addition, immunization against inhibin was reported to improve the fertility of domestic animals. Thus, a novel reproductive technique combining immunization against inhibin and the widely used Ovsynch protocol was proposed and tested in this study. Our results showed that immunization against inhibin has the potential to improve conception rates in cows, but also compromised luteal function. According to these results, additional luteal-stimulating treatments are suggested to further improve cow fertility based on immunization and the Ovsynch protocol.

Abstract

This study was conducted to investigate the feasibility of improving fertility in dairy cows via immunization against inhibin. Thirty-two cows were divided into Control (n = 11), Low-dose (n = 10) and High-dose (n = 11) groups. The High-dose and Low-dose cows were treated with 1 and 0.5 mg of the inhibin immunogen, respectively. All the cows were subjected to the Ovsynch protocol from the day of antigen administration and were artificially inseminated. Blood samples were serially collected over a 24-day period from the start of the Ovsynch protocol to 14 days after insemination. The results showed that immunization against inhibin dose-dependently increased the plasma concentrations of follicle-stimulating hormone (FSH), estradiol (E2), and activin A, but decreased progesterone (P4) concentrations in the luteal phase. Immunization also increased the plasma interferon (IFN)-τ concentrations in pregnant cows on day 14 after initial insemination. The conception rates in High-dose (45.5%) and Low-dose (40%) cows marginally increased compared to that in Control cows (27.3%), but the increases were not significant (p > 0.05). In conclusion, a single immunization against inhibin has the potential to improve conception rates, despite impaired luteal development. To further improve the reproductive performance of dairy cows, additional luteal-stimulating treatments are suggested in combination with immunization against inhibin and Ovsynch techniques.

Cloning expression and immunogenicity analysis of inhibin gene in Ye Mule Aries sheep

Background

Ye Mule Aries sheep is one of the most important sheep breeds in Xinjiang, China. This breed is well adapted to harsh environmental conditions and displays strong disease resistance, fast growth, and high cold tolerance. To analyze the clonal expression and immunogenicity of the Ye Mule Aries sheep inhibin gene, total RNA was extracted from sheep ovarian tissue and used as a template to generate a eukaryotic expression vector and study inhibin immunogenicity.

Methods

Primers were designed to amplify the inhibin A gene via polymerase chain reaction and the amplified product was cloned between the ScalI and EcoRI restriction sites of the expression vector pEGFP-N1 to construct a recombinant plasmid, pEGFP-INHα. Following the validation of successful cloning, the pEGFP-INHα plasmid was transfected into BHK cells to verify expression in eukaryotes and subsequently utilized as an antigen in rabbits. Rabbits were tested for anti-inhibin antibodies and serum follicle-stimulating hormone (FSH) concentrations.

Results

The analysis of the INHα gene sequence revealed that INHα is 1109 bp long and is translated to an approximately 40 KDa protein. Bioinformatics approach indicated that the INHα gene is highly conserved between organisms. Immunization with the eukaryotic expression vector, pEGFP-INHα, which expresses the INHα gene elicited immune response and generatigeneration on of anti-INHα antibody. The antibody had a significant regulatory effect on the serum concentration of FSH in rabbits and led to higher levels of FSH, indicating increased ovary function.

Conclusions

The present work resulted in a successful construction of eukaryotic expression plasmid pEGFP-INHα and verified the immunogenicity of this highly conserved protein. Further, the expression of pEGFP-INHα was shown to have a significant impact on the secretion of FSH, indicating a potential regulatory role in ovarian function. In conclusion, our current findings can serve as a working model for studying the effect of INHα on the breeding performance of Ye Mule Aries sheep, providing a novel strategy to improve their reproduction rates.

The stimulatory effect of subluteal progesterone environment on the superovulatory response of passive immunization against inhibin in goats

The objective of the current study was to investigate the effect of subluteal progesterone environment on the efficacy of the ovarian responses in goats passively immunized against endogenous inhibin. Twelve cycling female Shiba goats were synchronized using two doses of prostaglandin F2α 11 days apart. After detection of ovulation (D0, by ultrasonography), goats were randomly assigned into 2 groups: (1) Subluteal P4 group (SLP; n = 6), treated with a previously once-used controlled intravaginal progesterone-releasing device (ou-CIDR) intravaginal from D 6 to D 12 concurrently with a luteolytic dose of PGF2α at D6 (2) Normal Luteal P4 group (NLP; n = 6), had neither ou-CIDR nor PGF2α. In both groups, goats were treated with an intravenous injection of 10 ml of inhibin antiserum at D10. After that, another luteolytic dose of PGF2α was administrated to goats in both groups at D12, and withdrawal of ou-CIDR in the SLP group. Detection of estrous behavior was checked again 24 h following PGF2α administration and or ou-CIDR withdrawal at 8 h intervals with a teaser buck. The follicle populations ≥4 mm in each goat were monitored through transrectal ultrasonography daily from 1 day after inhibin antiserum administration (0 h) and continued until ovulation had been detected (disappearance of large dominant follicles by ultrasonography). In addition, a repeated ultrasonographic scanning was performed 7 days after ovulation, and the ovulation rate had been estimated by counting the number of observed corpora lutea by ultrasonography. Blood samples were collected for measurement of plasma circulating inhibin binding activity, FSH, LH, estradiol (E2), and progesterone (P4) in both groups. Results revealed significant increases in maximum diameter of the preovulatory follicles (5.92 ± 0.17 mm vs 5.31 ± 0.26 mm; P < 0.05), and the mean maximum number of follicles ≥ 4 mm in diameter (18.45 ± 3.40 vs 12.15 ± 6.21; P < 0.05) in the SLP group compared with that of the NPL group. No significant differences were observed between both groups in term of inhibin binding activity %, and FSH. Following immunization, significant increases in the concentrations of circulating LH (at 72 h) and E2 (from 48 to 84 h) were noted in the SLP group as compared with the values obtained from the goats in the NLP group. Moreover, significant increases in ovulation rate (13.85 ± 1.40 vs 5.67 ± 2.10; P < 0.01) and subsequent P4 concentrations (from 192 to 288 h) were found in the SLP group as against those of the NLP group. In conclusion, maintaining a subluteal P4 environment concurrently with passive immunization against endogenous inhibin may improve the superovulatory response in female Shiba goats.

The efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes

The aim of this study was to evaluate the efficacy of an inhibin DNA vaccine delivered by attenuated Salmonella choleraesuis on follicular development and ovulation responses in crossbred buffaloes. A total of 158 crossbred buffaloes divided into four groups and were intramuscularly injected with 1×10(10) (T1, n=41), 1×10(9) (T2, n=37), 1×10(8) (T3, n=37) or 0 (C, n=43) CFU/ml bacteria delivered inhibin vaccine in 10ml PBS on day 0 and 14, respectively. All animals were administered with 1000 IU PMSG on day 28, 0.5mg PGF2α on day 30 and 200μg GnRH on day 32. The results showed buffaloes immunized with the bacteria delivered inhibin vaccine had significantly higher titers of anti-inhibin IgG antibody than control group (P<0.01). The number and diameter of large follicles (≥10mm) as well as ovulatory follicles in group T1 was significantly greater than group C (P<0.05). The growth speed of dominant follicles in group T1 was significantly faster than groups T3 and C (P<0.05), resulting in a greater conception rate in buffaloes with positive antibodies. These results demonstrate that immunization with the bacterial delivered inhibin vaccine, coupled with the estrus synchronization protocol, could be used as an alternative approach to improve fertility in crossbred buffaloes.

Molecular mechanisms of enhancing porcine granulosa cell proliferation and function by treatment in vitro with anti-inhibin alpha subunit antibody

BACKGROUND

This study was conducted to clarify the effect of the inhibiting action of inhibin on porcine granulosa cell proliferation and function, and to investigate the underlying intracellular regulatory molecular mechanisms.

METHODS

Porcine granulosa cells were cultured in vitro, and were treated with an anti-inhibin alpha subunit antibody, with or without co-treatment of follicle-stimulating hormone (FSH) in the culture medium.

RESULTS

Treatment with anti-inhibin alpha subunit antibody led to a significant increase in estradiol (E2) secretion and cell proliferation. Anti-inhibin alpha subunit antibody worked synergistically with FSH at low concentrations (25 microg/mL) to stimulate E2 secretion, but attenuated FSH action at high concentrations (50 microg/mL). Immunoneutralization of inhibin bioactivity increased FOXL2, Smad3, and PKA phosphorylation, and mRNA expression of the transcription factors CEBP and c-FOS. The expression of genes encoding gonadotropin receptors, FSHR and LHR, and of those involved in steroidogenesis, as well as IGFs and IGFBPs, the cell cycle progression factors cyclinD1 and cyclinD2, and the anti-apoptosis and anti-atresia factors Bcl2, TIMP, and ADAMTS were upregulated following anti-inhibin alpha-subunit treatment. Treatment with anti-inhibin alpha subunit down regulated expression of the pro-apoptotic gene encoding caspase3. Although expression of the pro-angiogenesis genes FN1, FGF2, and VEGF was upregulated, expression of the angiogenesis-inhibiting factor THBS1 was downregulated following anti-inhibin alpha subunit treatment.

CONCLUSIONS

These results suggest that immunoneutralization of inhibin bioactivity, through augmentation of the activin and gonadotropin receptor signaling pathways and regulation of gene expression, permits the development of healthy and viable granulosa cells. These molecular mechanisms help to explain the enhanced ovarian follicular development observed following inhibin immunization in animal models.

Oral vaccination with inhibin DNA delivered using attenuated Salmonella choleraesuis for improving reproductive traits in mice

The objective of this study was to examine the efficacy and safety of a novel inhibin vaccine containing inhibin α (1-32) fragments in mice. A recombinant plasmid pVAX-asd-IS was constructed by inserting recombinant inhibin α (1-32) and the hepatitis B surface antigen S into the plasmid in which the asd gene, rather than the kanamycin gene, was a selection marker. Ninety Kuming mice were divided into six groups consisting of 15 mice each. First group was (C1) injected with 200 µl of PBS, second (C2) received 1 × 10(10) CFU of crp(-) /asd(-) C500/pVAX-asd and served as vector control, third did not receive any treatment (C3), while fourth, fifth, and sixth group received 1 × 10(10) , 1 × 10(9) , 1 × 10(8) CFU of the recombinant inhibin vaccine crp(-) /asd(-) C500/pVAX-asd-IS (group T1, T2, T3), respectively. Western blotting demonstrated that recombinant expressed inhibin protein possessed immune function and that this plasmid could replicate for up to 40 generations stably. Vaccination with this strain at a dose of 1 × 10(10) CFU/200 µl per mouse induced high anti-inhibin antibody levels, significantly increased large-follicle production in T1 group (p < 0.05) and average litter size (p > 0.05) compared with control groups. Integration studies showed no evidence of inhibin fusion gene integrated into mice's genome 2-month after immunization. These results suggest that the vaccine described in the present study may provide a safe method to improve reproductive traits in animals. A trend towards increased litter size and significant increase in large follicle population depict that this vaccine may have direct application in large animal industry.

Effect of a DNA vaccine harboring two copies of inhibin α (1-32) fragments on immune response, hormone concentrations and reproductive performance in rats

The objective was to investigate the effects of a novel DNA vaccine (pcISI) harboring two copies of inhibin α (1-32) fragments on immune response, hormone concentrations and reproductive performance in rats. Female Wistar rats (n=18 per group) were immunized (twice, 4 wk apart) with 10, 50, or 100 μg (T1, T2 and T3, respectively), of the pcISI plasmid. At 4 wk after the second immunization, plasma antibody titers were higher (P<0.05) in T3 than in either T1 or T2 (0.341±0.123, 0.236±0.068, and 0.251±0.077, respectively, mean±SD). Concurrrently, plasma concentrations of FSH and estradiol were highest (P<0.05) in T3, and were higher (P<0.05) in T1 and T2 than in control groups. For antibody-positive rats, there was a correlation (P<0.01) between antibody titer and FSH concentrations after two pcISI immunizations. The number of mature follicles in the T3 group (46.00±4.65) was higher (P<0.05) than in two control groups (29.25±3.72 and 27.92±3.48), and also higher (P<0.05) than in T1 and T2 (37.17±4.99 and 38.75±7.09). Antibody-positive rats had more mature ovarian follicles than negative rats (46.75±4.23 vs. 35.60±3.38, P<0.05). Moreover, litter size and number of placentas were increased (P<0.05) in the pcISI immunization groups, except for the T1 group, compared to the control groups. In conclusion, the pcISI DNA vaccine successfully induced a humoral immune response, improved reproductive hormone concentrations, stimulated follicular development, and increased number of placentas and litter size. Furthermore, 100 μg yielded the best immune response.