母鸡抑制素的研究进展

前言哺乳动物抑制素（ｉｎｈｉｂｉｎ）是一种性腺糖蛋白，由α亚基和βＡ、βＢ亚基组成的异二聚体：α亚基和βＡ亚基构成抑制素Ａ；α亚基和βＢ构成抑制素Ｂ；βＡ和βＢ亚基则组成激活素（ａｃｔｉｖｉｎ）二聚体。卵泡液和外周还存在游离的α前体物，在母鸡，抑制素在卵巢、肾上腺、脑、肌肉等组织中表达。由于抑制素结构的复杂性，至今尚没有办法精确的测定鸡外周抑制素的量，给研究抑制素的生物学活性带来困难。但采用测定各组织中α亚基和βＡ、βＢ亚基ｍＲＮＡ的表达量，可以反映抑制素的来源、分布及其作用。本文总结了近年来母…     

抑制素对公畜生殖功能的调节作用

从公羊公牛和公马资料看，抑制素主要产生于睾丸，单独或与睾酮协同作用于垂体，抑制ＦＳＨ的分泌。抑制素浓度在公畜不同发育阶段。不同生殖状态和品种之间存在有差异。抑制素对ＦＳＨ的抑制作用主要是破坏ＦＳＨβｍＲＮＡ的稳定性。了解抑制素的生理作用和浓度变化可依其作为判定公畜性腺功能的措施，利用抑制素免疫可作为提高公畜生育力的手段。     

抑制素对公畜生殖功能的调节作用

从公羊公牛和公马资料看，抑制素主要产生于睾丸，单独或与睾酮协同作用于垂体，抑制ＦＳＨ的分泌，抑制素浓度在公畜不同发育阶段，不同生殖状态和品种之间存在有差异，抑制素对ＦＳＨ的抑制作用主要是破坏ＦＳＨβｍＲＮＡ的稳定性，了解抑制素的生理作用和浓度变化可依其作为判定公畜性腺功能的措施，利用抑制素免疫可作为提高公畜生育力的手段。     

抑制素免疫对羊生殖的影响

抑制素是一种主要由动物性腺（睾丸的支持细胞和卵巢的颗粒细胞）分泌的一种异二聚体糖蛋白激素,由两个二硫键连接两个不同的亚单位（α和β）构成。抑制素对垂体ＦＳＨ的分泌和／或合成具有选择性地抑制作用。抑制素免疫中和技术能特异性地刺激ＦＳＨ分泌,进而促进配子生成,提高动物繁殖力。西方把抑制素免疫对羊排卵率、产羔数、初情期、超数排卵和公羊繁殖性能的影响作一综述。     

太湖猪高繁殖力内分泌学机制的研究进展

综述了太湖猪高繁殖力内分泌学机制的研究进展,结果表明太湖猪促黄体素（ＬＨ）促卵泡素（ＦＳＨ）的高含量以及ＦＳＨ分泌对抑制素的抑制效应较不敏感,尤其是ＦＳＨ的高含量,很可能是太湖猪高排卵率的重要因素之一。     

抑制素主动免疫对山羊繁殖率的影响

选用８只母山羊随机分成两组,试验组用卵巢抑制素与血清蛋白偶合物进行主动免疫,探讨免疫对排卵率和血浆ＦＳＨ水平的影响。结果显示,试验组山羊的抗体效价分别为１：１２８、１：６４、１：３２和１：３２,且卵巢黄体数显著高于对照组（Ｐ〈０．０５）,ＦＳＨ平均水平极显著高于对照组（Ｐ〈０．０１）。这表明,抑制素主动免疫能够引起血浆ＦＳＨ水平的升高,提高排卵率,可以改善母山羊的繁殖性能。     

太湖猪高繁殖力内分泌学机制的研究进展

综述了太湖猪高繁殖力内分泌学机制的研究进展。结果表明太湖猪促黄体素（ＬＨ）、促卵泡素（ＦＳＨ）的高含量以及ＦＳＨ分泌对抑制素的抑制效应较不敏感,尤其是ＦＳＨ的高含量,很可能是太湖猪高排卵率的重要因素之一。     

超排山羊17β—雌二醇和促卵泡素与卵巢反应的关系

对１７只性周期正常的母山羊于性周期第八，九天应用ＦＳＨ－ＰＧＦ２α超排处理，同时将同期经受体作为对照，用放射免疫方法测定血浆１７β－雌二醇和促卵泡素浓度。试验发现，超排组排卵数和收集胚胎数显著高于对照组。在处理组中，有６头羊超排无效果。经ＦＳＨ处理后，１７β－雌二醇的血浆浓度呈上升趋势，于处理后８４ｈ达到峰值，此时表现发情，但超排有反应组的血浆逍度显著高于无反应组，发情时１７β－雌二醇浓度与排卵数     

鹌鹑卵泡发育过程中颗粒细胞黄体生成素受体mRNA的表达

用Ｎorthern杂交的方法研究了鹌鹑排卵泡内颗粒细胞黄体生成素受体（ＬＨＲ）mＲＮＡ的表达。在预计排卵前２０h和３h分别取出最大的３个卵泡（Ｆ１、Ｆ３卵泡）以及小黄卵泡（ＳＹＦ）,剥离颗粒层提取出总ＲＮＡ,并经变性凝胶电泳后将ＲＮＡ转移到滤膜上。杂交所用的探针是用特异的引物经反转录一多聚栈链式反应（ＲＴ－ＰＣＲ）扩增出编码ＬＨＲcＤＮＡ的细胞外区（ＥＣ）和跨膜区（ＴＭ）cＤＮＡ。结果表明,颗粒细胞ＬＨＲmＲ     

不同来源抑制素抗原对牛羊繁殖力影响研究

抑制素是一种由性腺分泌的糖蛋白,由α、β两个亚基组成。研究表明,它具有选择性抑制促卵泡素（FSH）合成和分泌的作用。最初在研究抑制素生理作用时发现,用卵泡液提取物免疫动物后,可提高排卵率,增加产仔数。另一方面的研究发现,在多产Booroola美利奴母羊卵巢中缺少具生物活性的抑制素,这说明这种母羊体内FSH浓度较高,这显然是由于该种母羊卵巢内缺少抑制素的结果。     

Expression of inhibin/activin subunits in the ovaries of fetal and neonatal mice

In the present study, the expression of inhibin/activin subunits in the mouse ovary from 13 days post-coitus (dpc) to 30 days postpartum (dpp) was investigated. Circulating FSH, LH, inhibin A, and inhibin B in neonatal to 30 dpp ovaries were measured. Inhibin/activin subunits (alpha, beta(A), beta(B) ) were weakly stained in 13 dpc ovarian stromal cells and increased with age. Inhibin alpha subunit was immunolocalized in follicular granulosa cells at each developmental stage. In 30 dpp ovaries, several large antral follicles were strongly stained for inhibin alpha subunit. Inhibin beta(A) subunit was weakly immunolocalized in granulosa cells until 20 dpp. Moreover, 2 to 3 antral follicles from 20 to 30 dpp were strongly stained for inhibin beta(A) subunit. There was relatively high immunoactivity for inhibin beta(B) subunit in neonatal to 30 dpp mouse ovaries. All three inhibin subunits were stained in theca-interstitial cells from 15 dpp onward. RIA data showed that a temporal increase in circulating FSH occurred around 10 dpp, while the plasma concentrations of LH were sustained at a relatively higher level from 8 to 15 dpp. Inhibin B was detectable in circulation early at 1 dpp (day of birth), and a clear increase in inhibin B occurred around 8 dpp. Circulating inhibin B gradually increased from 20 dpp to 30 dpp, indicating a negative correlation with FSH. Inhibin A levels were only measured on 25 and 30 dpp, and the levels were low. These results suggest that inhibins play an important role in early folliculogenesis in mice. In addition, inhibin B seems to be the main functional isoform from the neonatal to prepubertal stage in the mouse ovary.     

Downregulation of the expression of inhibin α subunit and betaglycan in porcine cystic follicles

Inhibins, as members of the transforming growth factor beta (TGF-β) superfamily, downregulate the synthesis and secretion of follicle-stimulating hormone (FSH) in an endocrine manner. The role of inhibin/betaglycan in the ovary regulation recently gained attention. To date, no data exist on the function of inhibin α subunit and betaglycan in cystic follicles. In this study, the expressions of inhibin α subunit and betaglycan in cystic follicles were investigated using immunohistochemistry, real-time PCR and Western blot analysis. Both inhibin α subunit and betaglycan immunoreactivities were mainly localized in the granulosa cells of follicles. Expression of inhibin α subunit and betaglycan was inferior in cystic follicles compared with that in normal large follicles. However, the result of enzyme-linked immunosorbent assay showed no significant difference in the decreasing in concentration of inhibin α subunit in cystic follicular fluid compared with the control (P>0.05). In this study, we explored the effects of FSH on betaglycan expression in granulosa cells in vitro. As expected, a significant increase in the expressions of betaglycan mRNA and protein in granulosa cells was observed in response to exogenous FSH (30 ng/ml) (P<0.05) compared with the control. Consequently, this study provides evidence that the expressions of inhibin α subunit and betaglycan are inferior in cystic follicles, and this may be caused by the decrease in FSH in the presence of a cystic follicle.     

Changes in the concentration of mRNAs for the inhibin subunits in ovarian follicles after administration of gonadotropins to progestin treated ewes.

RNA was extracted from single or small groups of ovine ovarian follicles after treatment of ewes with FSH and/or LH. The content of mRNA for the alpha-inhibin and beta A-inhibin subunits was analyzed by hybridization with specific cDNA probes. All ewes were treated with progestin vaginal pessaries to suppress spontaneous preovulatory follicle maturation and ewes were given three intramuscular injections of gonadotropins at 8-hr intervals starting 24 hr prior to collection of ovaries. In experiment I, both Schering-FSH and NIDDK-oFSH-17 (oFSH) significantly increased alpha- and beta A-inhibin mRNA per ewe in 2-5 mm follicles and tended to increase alpha- and beta A-inhibin mRNA in large (greater than 5 mm) follicles. In experiment II, oFSH and NIDDK-oLH-25 (oLH) were administered in a 2X2 factorial arrangement. Separate administration of oFSH or oLH increased (P less than .05) the alpha-inhibin mRNA concentration in large follicles. alpha-inhibin mRNA concentration in 4-5 mm follicles was also increased by oFSH but was decreased by oLH. Concomitant treatment with oFSH and oLH did not change alpha-inhibin mRNA concentrations from those measured in oFSH treated ewes. In experiment II, beta A mRNA concentrations followed a pattern similar to that of alpha A mRNA, but the differences were not statistically significant. We conclude that, in the ewe, exogenous FSH increases the concentration of inhibin mRNA in the whole follicle. The ability of exogenous oLH to alter expression of the inhibin subunit genes may depend upon the stage of follicle maturation.     

Secretion of inhibin in female Japanese quails (Coturnix japonica) from hatch to sexual maturity

To clarify the cellular source and secretory pattern of inhibin in the Japanese quail during follicular development, the plasma concentrations of immunoreactive (ir) inhibin were measured from 1 to 7 weeks after hatching. Localization of the inhibin/activin alpha, beta A and beta B subunits was investigated by immunohistochemistry. To monitor development of the pituitary and ovarian functions, the plasma luteinizing hormone (LH) and progesterone concentrations were also measured. Ovarian weight increased gradually until 6 weeks of age and then abruptly increased at 7 weeks of age just at the onset of egg production. Plasma concentrations of LH increased significantly at 6 weeks of age. The plasma concentrations of ir-inhibin and progesterone and the pituitary contents of LH also increased significantly at 7 weeks of age. Immunohistochemically, the inhibin/activin alpha, beta A and beta B subunits were localized in the granulosa cells of all follicles during different stages of development from 1 to 7 weeks after hatching. The inhibin alpha, beta A and beta B subunits were also found in the interstitial cells but not theca cells of all follicles. These results demonstrated that the plasma concentrations of ir-inhibin of the female Japanese quails rose with ovarian development. The immunohistochemical results suggested that granulosa and interstitial cells are the major source of ovarian inhibins in female Japanese quails.     

Localization of inhibin alpha-, betaA- and betaB-subunits and aromatase in ovarian follicles with granulosa theca cell tumor (GTCT) in 6 mares

To clarify the morphological and immunohistochemical characteristics in mares with granulosa theca cell tumor (GTCT), the localization of inhibin subunits (alpha, betaA, betaB) and aromatase in the granulosa cell layers and theca layers in the ovarian follicles were determined by immunohistochemical staining. The follicles were obtained from the ovaries of 6 mares with GTCT and 4 normal mares as controls. Immunohistochemically, inhibin alpha-subunit was localized in the granulosa cells of all follicles showing different sizes in all GTCT cases and betaA- subunit was localized in two GTCT cases in all sized follicles. But inhibin betaB- subunit and aromatase were not localized in GTCT cases. On the other hand, inhibin alpha-, betaA-, and betaB-subunits and aromatase were localized in the large and medium sized follicles, but inhibin betaA- and betaB-subunits and aromatase were not stained in the small sized follicles in normal cases. These findings suggest that some mares with GTCT can secrete dimeric inhibin (inhibin A), but all GTCT cases cannot secrete inhibin B. By the results of aromatase staining it is clear that testosterone is not converted into estradiol due to the lack of aromatase in the GTCT follicles.     

Effects of vertically transferred 3,3',4,4',5-pentachlorobiphenyl on gene expression in the ovaries of immature Sprague-Dawley rats

We have previously shown that 3,3',4,4',5-pentachlorobiphenyl (PCB-126) vertically transferred from dams potentially exerts a direct effect on the ovaries of offspring and adversely affects female puberty. To investigate its toxicological targets in ovarian tissues, mRNAs encoding representative peptides that regulate follicular development in granulosa cells, theca cells, and oocytes were quantified using ovaries collected on postnatal days (PND) 5, 15, and 24 from the offspring of dams administered oral doses of 0, 1 or 3 microg/kg PCB-126 starting 2 weeks prior to mating and continuing until 20 days after delivery. Quantification using the real-time RT-PCR method revealed that PCB-126 lowered the amounts of mRNAs that encoded the inhibin alpha- and inhibin/activin beta A-subunits from PND 15 onwards; the amounts of mRNAs for inhibin/activin beta B-subunit, follicle-stimulating hormone (FSH) receptor, and aromatase on PND 15; and the amounts of luteinizing hormone receptor mRNA on PND 24 compared with those of the age-matched controls. In contrast, no differences were noted for mRNAs encoding c-kit, growth differentiation factor-9, bone morphogenetic protein-15, or kit ligand for any of the age groups examined. The serum FSH level on PND 24 was higher than that in the control. Since the earliest effects on the mRNAs in the rat ovaries were observed in those expressed in the granulosa cells of the growing follicles after the antral follicles had developed, molecules in granulosa cells but not in oocytes during the early stages of the antral follicles might be the primary targets of vertically transferred PCB-126.     

Effect of active immunization of pony mares against recombinant porcine inhibin alpha subunit on ovarian follicular development and plasma steroids and gonadotropins

Two pony mares were immunized against recombinant porcine inhibin alpha subunit three times with 39 day intervals. Clinical findings and endocrinological changes before immunization were taken as the control. The first significant rise in the anti-inhibin titre (P<0.05) in the circulation was found 27 days after the first injection. Maximum binding activity was reached by the 12th day after the second booster dose. The number of small, medium and large sized follicles had increased significantly compared to before immunization (11.75 +/- 4.30, 2.75 +/- 0.69 and 2.51 +/- 0.63 vs 6.50 +/- 1.43, 1.83 +/- 0.44 and 1.33 +/- 0.38, respectively), but the ovulation rate remained unchanged after immunization. The average plasma concentration of FSH and estradiol-17beta during the estrous cycle increased significantly (P<0.05) after immunization. These results suggest that immunization against inhibin is a useful tool to increase the number of ovarian follicles during the estrous cycle of pony mares. Moreover, the present study supported the concept that inhibin plays a major role in the control of follicular growth through its inhibitory effect on FSH secretion synergistically with steroid hormones.     

Comparison of aryl hydrocarbon receptor gene expression in laser dissected granulosa cell layers of immature rat ovaries

In order to understand ovarian toxicity of aryl hydrocarbon receptor (AhR) agonists, in situ gene expression of the AhR was examined during follicle development in immature rats. In situ hybridization on frozen sections of ovaries from 24-day-old Sprague-Dawley rats showed that the AhR mRNA was localized in the granulosa cells and occasionally in the theca cells of the follicles irrespective of the developmental stage. In situ gene quantification on granulosa cell layers collected by laser microdissection further revealed that the granulosa cells expressed less AhR mRNA according to development of belonging follicles, but more β-subunit of inhibin A mRNA, a quality control gene. These results may help to elucidate vulnerable developmental stages of follicles to toxicities of the AhR agonists.     

Histochemical localization of inhibin and activin alpha, beta A and beta B subunits in rat gonads.

The localization of alpha, beta A and beta B subunits of inhibin/activin polypeptides was studied in the ovary and testis of sexually mature, immature, and embryonic rats. Specific staining with these three subunits was also evident in the oocytes from embryonic to mature female rats. This result suggests that inhibin- and activin-like substances may be produced in the oocytes and these substances may play a role in the oocyte growth and differentiation. Judging from the intensity of immunoreaction in mature female rats, the three subunits should be produced more abundantly in luteal cells than in the granulosa cells. Immunoreactive alpha, beta A and beta B subunits were observed in the cummulus oophorous in the morning (11:00), but not in the evening (23:00) on proestrus. The results are in well agreement with the previous report that inhibin alpha and beta A subunit mRNA signals decline on proestrus evening. It is supposed that the cyclic change may be related with physiological phenomena prior to the ovulation, such as primary gonadotropin surges, loss of cummulus-oocyte gap junctions, or germinal vesicle breakdown. In both germ cells and Sertoli cells of the testis, alpha, beta A and beta B subunits were more abundant in the embryonic rat than in the mature rat. Although clear reactions with beta A and beta B subunits were detected in Leydig cells, alpha subunit was not detectable in the cells throughout the developmental stages examined.