精子发生的血清标志物——抑制素-B

抑制素 B是睾丸来源的糖蛋白激素 ,由两个亚单位共价连接而成。成年男性体内血清抑制素 B水平与FSH呈显著负相关 ,对FSH起负反馈作用。男性出生后不久 ,血清抑制素 B水平逐渐上升 ,于青春期 Ⅱ 期达到成年人水平 ,从青春期 Ⅲ期至成年 ,抑制素 B与FSH之间一直维持负相关关系。 2 0～ 30岁时 ,抑制素 B水平到达另一个高峰 ,此后抑制素 B水平随年龄增加逐渐降低。生精功能低下与生精阻滞男性血清抑制素 B水平显著低于正常生精功能的男性 ,唯支持细胞综合征 (SCO)男性血清抑制素 B水平极低 ,SCO的发生与血清抑制素 B水平显著相关 ,血清抑制素 B水平还与睾丸体积、精子总数显著相关。抑制素 B水平反映了整个睾丸组织的功能 ,是输精管道的直接产物 ,成年男性血清中维持可检测的抑制素 B水平需要生精细胞的存在 ,因此抑制素 B被认为是男性精子发生的血清标志物。血清抑制素 B测定可用于评价男性不育病人的生精功能 ,儿童隐睾、性早熟的诊断 ,对非阻塞性无精子症病人睾丸精子抽吸 (TESE)的预测 ,监测放、化疗对男性生精功能的损伤等     

无精子症、少精子症患者精浆和血清中抑制素B水平测定

抑制素是由睾丸的Leydig和Sertoli细胞产生的调节生殖内分泌与评估男性生殖功能的一个重要的激素[1].我们采用ELISA法对无精子、少精子症患者的精浆和血清中的抑制素B进行检测,以进一步了解抑制素B水平与男性生殖功能的关系.     

抑制素与男性生殖功能

抑制素是由睾丸的Leydig和Sertoli细胞产生的激素。它反馈到垂体前叶从而明显降低FSH的分泌。近年来的研究表明，抑制素对调节生殖内分泌与评估男性生殖功能的重要性值得进一步的探讨。     

抑制素与男性生殖功能

抑制素是由睾丸的Leydig和Sertoli细胞产生的激素。它反馈到垂体前叶从而明显降低FSH的分泌。近年来的研究表明 ,抑制素对调节生殖内分泌与评估男性生殖功能的重要性值得进一步的探讨。     

抑制素B在评估男性睾丸生精功能方面的研究进展

抑制素B主要由睾丸内Sertoli细胞分泌并对成年男性促卵泡激素(FSH)分泌起负反馈作用,抑制素B的分泌调节受年龄、体重指数的影响,血清抑制素-B水平与睾丸体积、精子总数显著相关,血清抑制素-B测定可用于评价男性不育病人的生精功能,能有效确定唯支持细胞综合征,可作为监测男性生殖系统疾病影响生精功能效应的指标。     

抑制素与男性生殖功能

1935年发现了在睾丸中有能够抑制FSH(促卵泡成熟激素)分泌的抑制素(inhibin),经过分离和纯化成功获得抑制素-B(inhibin-B,INH-B)具有生物活性.越来越多的研究表明,睾丸中的抑制素参与了垂体功能的调节,并在睾丸生精过程中通过旁分泌的方式调节支持细胞的功能[1],尤其INH-B与男性不育的病因学和组织学密切相关.本文就此综述.     

孕激素与男性生殖

孕激素对男性下丘脑 垂体 睾丸轴具有反馈抑制作用。垂体及生殖腺均检出明显的孕激素受体mRNA ,且呈不同分布特点。人生精细胞和精子中含有一定数量的孕酮 ,提示孕激素与精子产生的数量、精子胞膜完整性和染色体稳定性以及受精有关。孕、雄激素合用引起的可逆性抑制精子发生 ,其机制在于孕激素反馈抑制促性腺激素的分泌 ,近来还发现其可能直接作用于睾丸及附睾 ,在局部直接发生效应。生理剂量的孕激素可以促进雄激素依赖的雄性性行为 ;而药理浓度孕激素可以抑制雄性性行为 ,其机制不仅仅是通过降低睾酮水平 ,而且在中枢神经系统有直接的作用。孕烷衍生物具有部分选择性抑制Ⅱ型 5α 还原酶的作用 ,提示用于前列腺疾病有更多益处     

血清抑制素B与睾丸生精功能

目的　探讨血清抑制素B与睾丸生精功能的关系。方法　将男性不育症病人分为原发性无精子症、严重少精子症和梗阻性无精子症 3组 ,另设正常对照组 ,分别测定其抑制素B、FSH及精子密度。结果　上述 4组的抑制素B浓度分别为 4 7.36± 32 .85 ,2 0 0 .92± 86 .4 4 ,2 82 .4 0± 98.2 1,2 36 .79± 10 7.70。结论　血清抑制素B可直接反映睾丸的生精功能状态 ,因而是判断男性生育力更有效的指标     

抑制素B与精索静脉曲张关系的研究进展

抑制素B主要由睾丸支持细胞合成的可特异性地抑制垂体FSH合成与分泌的一种糖蛋白激素,与生精功能密切相关。精索静脉曲张指精索内蔓状静脉丛的异常迂曲、扩张,可以引起睾丸生精功能障碍,是导致男性不育常见的病因。越来越多的证据表明,血清抑制素B水平与精索静脉曲张程度呈负相关,检测血清抑制素B水平能评估精索静脉曲张患者生精功能的损害程度,并可预测精索静脉曲张术后的疗效,在精索静脉曲张疾病的诊疗中有潜在的应用价值。     

抑制素B与生殖

抑制素B(inhibin B,INHB)是转化生长因子-β(TGF-β)超家族成员之一,由睾丸的Sertoli细胞和卵巢中、小窦状卵泡的颗粒细胞产生,具有反馈性抑制垂体卵泡刺激素(FSH)分泌和调节两性生殖细胞发育的重要功能,同时还是卵巢颗粒细胞和睾丸Sertoli细胞功能的一个特异性标志物,与两性生殖关系密切。     

Serum inhibin B and follicle-stimulating hormone levels as markers in the evaluation of azoospermic men: a comparison

Inhibin B is a glycoprotein hormone produced mainly by Sertoli cells of the testes in the adult male. It selectively suppresses the secretion of pituitary follicle-stimulating hormone (FSH) and has local paracrine actions in the testes. Its measurement is useful for investigating the role of inhibin B in male gonadal dysfunction. The objective of this study was to investigate the efficacy of serum inhibin B in men with nonobstructive azoospermia in comparison with FSH. Serum concentration of FSH was measured using microparticle enzyme immunoassay, inhibin B by specific solid phase sandwich enzyme-linked immunosorbent assay in men with nonobstructive azoospermia (n = 46) and control fertile men (n = 5). Mean inhibin B and FSH level was 104.6 pg ml(-1) and 4.0 mIU ml(-1) in control men whereas the value for nonobstructive azoospermic men was 17.06 pg ml(-1) and 31.1 mIU ml(-1) respectively. Inhibin B and FSH levels were significantly different in azoospermia than controls (P < 0.0001). There were six cases of nonobstructive azoospermia with normal inhibin B. Testicular histology did not find any evidence of spermatogenesis in three cases with normal inhibin B. This demonstrated that inhibin B was not a superior predictor for testicular function in our study.     

Serum levels of inhibin B in men with different causes of spermatogenic failure

Inhibin B appears to be the physiological feedback signal for FSH. Herein the determination of serum levels of inhibin B, FSH, LH and testosterone in 148 infertile patients and their association with clinical findings and seminal parameters are reported. A significant negative correlation of FSH and inhibin B (r = -0.60) was found. LH levels showed a significant inverse correlation (r = 0.37), but a weak regression (c0 = 0.01). No correlation with testosterone levels occurred. A significantly positive correlation was observed between testis volume and inhibin levels (r = 0.39) as well as between sperm count and inhibin levels (r = 0.39). To evaluate whether the secretion of inhibin B depends on the nature of damage to the Sertoli cells, inhibin levels in 23 patients with varicocele; eight after cryptorchidism, and 16 after hemiorchiectomy were compared to those of other patients without these diseases, but identical sperm count. No significant differences were found. In 20 men undergoing testicular biopsy, inhibin levels were compared to histology. Although the men with Sertoli-cell-only syndrome had significantly lower levels ((15.83 +/- 12.2) pg ml-1) than those with normal spermatogenesis ((183.8 +/- 112.3) pg ml-1), a distinction between patients with hypospermatogenesis from those with normal spermatogenesis was not possible on the basis of inhibin levels. Between these groups, the distinction was better achieved by the FSH levels (sensitivity of 85%). We conclude that inhibin B levels are a serum marker of Sertoli cell function, but the prediction of the quality of spermatogenesis is not superior to that of FSH levels.     

Serum inhibin pro alphaC in infertile men.

Specific assays have been developed for bioactive inhibin dimers, inhibin A and B, and inhibin alpha-subunit precursor pro alphaC. To better understand the role of serum inhibin pro alphaC in infertile men, the authors measured these forms of inhibin in sera from 39 infertile men and analyzed inhibin relationships with serum gonadotropins, testosterone, and estradiol. All subjects had oligozoospermia. Inhibin A levels were undetectable in all subjects. Inhibin B concentrations were 117 +/- 59 pg/mL. Inhibit B concentrations correlated negatively with serum FSH (r = .584, p < .0001) and positively with sperm count (p < .01) and bilateral testicular volume (r = .607, p < .0001). The concentration of pro alphaC was 556 +/- 236 pg/mL (normal range, 446 +/- 28). Inhibin pro alphaC showed no correlation with serum FSH, LH, testosterone, sperm concentration, and bilateral testicular volume. In addition, inhibin pro alphaC was not correlated with inhibin B. Pro alphaC is unlikely to be a useful marker for spermatogenesis in infertile men compared with inhibin B.     

抑制素B βB亚单位在不同病理分型的无精子症患者睾丸组织中的表达

目的:探讨抑制素B(INH B)βB亚单位在不同生精功能状态的人睾丸组织中的表达情况。方法:对83例无精子症患者进行睾丸组织病理检查诊断,根据病理形态的不同分为:唯支持细胞综合征型(n=21);生精功能低下型(n=20);生精阻滞型(n=24);生精功能基本正常型(n=18)。选择上述各型结构完整的睾丸组织,分别应用免疫组化法(SP)对血清INH B βB亚单位在不同生精功能状态的睾丸组织,进行定位研究。结果:各型睾丸组织内均存在血清INH B βB的表达,其分布特点为:间质细胞(Leydig cell)和早期生精细胞多为强阳性表达,呈深棕黄色;支持细胞(Sertoli cell)多为阳性表达;而晚期精子细胞和成熟精子未见表达;生精小管管周类肌细胞呈弱阳性表达。结论:INH B可能是睾丸Sertoli细胞和早期生精细胞的一个联合产物。     

Low inhibin B levels alone are not a reliable marker of dysfunctional spermatogenesis in childhood cancer survivors

Hormone and semen analyses were carried out to examine the diagnostic value of hormones and hormone combinations as markers of spermatogenesis in male patients who had received oncological treatment in childhood. Hormone analyses from 73 participants and spermiograms from 42 participants were evaluated. Spearman's correlation coefficients and measures of diagnostic accuracy were calculated for the hormone and semen analysis values. Inhibin B levels of <80 ml/ml, follicle-stimulating hormone (FSH) levels of >10 IU l(-1) and a combination of the two parameters showed positive predictive values for azoospermia of 0.423, 0.6154 and 0.6667 respectively. While 32% of the 73 participants showed a combination of abnormal inhibin B and FSH values, which strongly indicates impaired spermatogenesis, 31% of the 42 spermiogram results revealed azoospermia. The hormone and semen analyses showed that approximately one-third of the participants had fertility impairment. Inhibin B alone thus does not reflect spermatogenesis as well as inhibin B in combination with FSH in patients who have undergone cancer treatment in childhood. Both parameters should therefore be evaluated in paediatric cancer follow-up programmes to allow better identification of treatment regimens that cause persistent azoospermia in male childhood cancer survivors.     

Possible relationship between seminal plasma inhibin B and spermatogenesis in patients with azoospermia

Inhibin B is bidirectionally secreted by Sertoli cells, basal secretion into the circulation exerts negative feedback on follicle-stimulating hormone secretion, and serum inhibin B is considered a marker of spermatogenesis. The precise role of apical secretion is unknown. The objective of our work was to study the relationship between seminal inhibin B and spermatogenesis. Dimeric inhibin B was measured by immunoassay in seminal plasma of volunteers with normozoospermia (n = 10, group 1), in men after vasectomy (n = 10, group 2), and in men with azoospermia (n = 50, group 3). Testicular biopsy and testicular sperm extraction were performed in men with azoospermia. Seminal inhibin B levels were higher in men in group 1 than in men in groups 2 and 3 (P <.0001). In seminal plasma, inhibin B presents a positive correlation with alpha glucosidase activity (r =.37, P =.002). Seminal inhibin B is inversely related with serum FSH (r = -.58, P <.001), and presents a weak positive correlation with serum testosterone concentration (r =.29, P =.03). No difference was found between inhibin B levels in seminal plasma of patients with nonobstructive or obstructive azoospermia, and between positive or negative outcome of TESE. We conclude that inhibin B secretion by Sertoli cells is differentially regulated. The contribution of accessory sex glands limits the use of seminal plasma inhibin B as a marker of spermatogenesis.     

Effect of cryptorchidism and orchidopexy on inhibin secretion by rat Sertoli cells

The present study explored the effects of experimental bilateral cryptorchidism (of 21-, 28-, and 35-days duration) and orchidopexy (14 and 42 days) in the adult rat on the secretion of inhibin by cultures of isolated Sertoli cells. Changes in serum levels of gonadotropins, testis weight, and spermatogenesis also were assessed to verify the effectiveness of the surgical procedures. Cryptorchidy resulted in a progressive decline in testicular weight and a loss of germ cells, associated with increasing serum levels of FSH and LH. Inhibin secretion in vitro became nondetectable by 28 days after surgery. At 42 days after orchidopexy, spermatogenesis showed qualitative recovery, with a small increase in testes weight. Levels of LH in the circulation declined, but only to twice the intact control levels. However, inhibin secretion and serum FSH levels returned to nearly normal values. These results indicate that bilateral cryptorchidism severely impairs the secretion of inhibin and possibly other Sertoli cell functions which may account, at least partly, for the increase in circulating FSH levels and the arrest of spermatogenesis. The effects of cryptorchidism on these parameters can be reversed to a large degree by orchidopexy.     

Is inhibin B involved in the toxic effect of lead on male reproduction?

Human studies indicate exposure to lead is associated with decreased sperm quality with modest, if any, effects on conventional reproductive endocrine profile. Inhibin B is a marker of Sertoli cell function and spermatogenesis. The present study evaluates possible effects of lead exposure on serum levels of inhibin B in a group of lead workers as compared with a non-exposed group of hospital personnel. The study population included 68 healthy Belgian workers from a lead smelter (Hoboken, Belgium) and for comparison a control group of 91 hospital personnel (University Hospital Ghent, Belgium). Semen analysis and measurement of current blood lead levels and serum levels of inhibin B, follicle stimulating hormone (FSH) and estradiol (E2). Lead workers had significantly lower sperm concentration (35 vs. 51 million/mL) and higher serum inhibin B (259 vs. 177 pg/mL) as well as lead blood levels 30.9 vs. 3.4 mug/dL) compared with the hospital personnel (all p < 0.05). Serum FSH and E2 levels were similar in both groups. Overall, inhibin B levels correlated significantly positively with blood lead levels and sperm concentration while it was negatively correlated with serum FSH. In multiple regression analysis of data from all participants, blood lead and serum FSH (p < 0.0001 for both) followed by sperm count (p = 0.007) were selected as the only independent variables for inhibin B with an R-adjusted coefficient of determination of 0.3714. The results of the present study suggest that the exposure of the cells of Sertoli to excessive amounts of lead results in inappropriate inhibin B overproduction that may be involved in the impairment of spermatogenesis.     

Inhibin B levels in peripheral vein do not correlate with inhibin B levels in the spermatic vein in adolescents with varicocele

This study was conducted to evaluate the inhibin B with FSH and LH levels on spermatogenesis in varicocele patients. The study group consisted of 10 adolescent with left idiopathic varicocele of grade II and III. Blood specimens were obtained from dilated spermatic vein and peripheral vein simultaneously. Peripheral samples were also collected from 7 healthy children as controls. Inhibin B was measured with ELISA inhibin B kits. FSH and LH were analyzed by radioimmunoassay techniques. The results were analyzed using Mann-Whitney U and Spearman's rank tests. A value of p < 0.05 was considered significant. Peripheral FSH, LH and inhibin B levels were the same in the study and control group (p > 0.05). Mean inbibin B levels of spermatic vein were significantly higher than the control and peripheral blood of the study groups (p < 0.05). FSH, LH, and inhibin B levels correlated poorly each other (p > 0.05). Preoperative serum inhibin B concentration could not reliably predict a response to varicocelectomy, but the increase in inhibin B levels after treatment might suggest an improvement in testicular function.