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

A Serum Marker of Spermatogenesis -Inhibin B

Inhibin B is a glycoprotein secreted by testis, consisting of two disulfide-linked subunits, an alpha-subunit and a beta B-subunit. Serum inhibin B levels are significantly negatively correlated with the serum FSH levels in males, exerting a negative feedback on FSH secretion. In males the circulating levels of inhibin B increase shortly after birth and peak at 4-12 months of age, then decrease to low levels from 3-9 year. From the onset of puberty, the levels of inhibin B gradually increase. By pubertal stage II, the adult levels of inhibin B have been reached. At stage III of puberty, a negative correlation between inhibin B and FSH levels is present and persists from stage III of puberty onward. At 20-30 year of age, the levels of inhibin B reach another peak, then gradually decline with increasing age. The men with hypospermatogenesis and spermatogenesis arrest have significantly lower levels of inhibin B than those with normal spermatogenesis. The men with Sertoli-cell-only syndrome (SCO) have extremely low levels of inhibin B. There is a closely correlation between the presence of SCO and the level of serum inhibin B. A significantly positive correlation is also observed between testis volume and inhibin B level, as well as between sperm count and inhibin B level. The inhibin B is a direct product of the seminiferous tubules, reflecting the total testicular tissue. The measurable inhibin B production in adult requires the presence of germ cells. Inhibin B is regarded as a serum marker of spermatogenesis. The determination of serum inhibin B in males can be used to assess the spermatogenesis of infertile men, to diagnose the cryptorchidism and precocious puberty, to predict the outcome of testicular sperm extraction in men with non-obstructive azoospermia, and to evaluate the damage to spermatogenesis in men after radiotherapy or chemiotherapy.