精子发生的内分泌激素调节

下丘脑-垂体-睾丸轴系对男性生殖功能起着关键性作用,精子发生是这个轴系精密调节的结果。下丘脑促性腺激素释放激素(GnRH)脉冲式释放控制了卵泡刺激素(FSH)和黄体生成素(LH)的波动性分泌,GnRH脉冲频率的变化调节垂体促性腺细胞分泌两种不同的激素,是一种独具一格的机制。促性腺激素抑制激素(GnIH)于2000年首次从鹌鹑垂体鉴定出来。GnIH的发现使我们更深入地了解下丘脑激素对垂体促性腺细胞的调节。哺乳动物的GnIH神经元定位于下丘脑背内侧核,轴突延伸至正中隆突。GnIH通过其受体GPR147抑制垂体促性腺细胞的功能。成年男子的精子发生需要FSH和睾酮的共同作用,任何二者之一缺失会损害Sertoli细胞的分化和功能以及生精细胞在精子发生过程的发育。睾酮至少从4个方面促进精子发生:(1)紧密连接(tight junction)的形成和功能;(2)附睾的发育和功能;(3)生精细胞的发育;(4)精子释放。在体研究提示,雌激素亦对精子发生起重要作用,雌二醇调节小鼠精原细胞系和精母细胞系调亡和抗调亡之间的平衡。     

精子发生阻滞不育患者睾丸雌激素受体α的表达

目的:探讨雌激素受体α(ERα)在睾丸的表达与精子发生阻滞的关系。方法:用HE染色技术检查120例不育症患者睾丸活检标本,其中精子发生阻滞患者标本应用免疫组化法检查ERα的表达,并以10例健康人睾丸组织作为对照。结果:120例标本中符合精子发生阻滞病理诊断标准者有31例(占25.8%)。正常健康人睾丸组织中,ERα在睾丸支持细胞、类肌细胞和间质细胞的细胞核内表达,生精上皮细胞不表达;而在精子发生阻滞的睾丸组织中,ERα也在睾丸支持细胞、类肌细胞和间质细胞的细胞核内表达,但表达较弱,生精上皮细胞不表达。两者表达强度存在显著性差异(P<0.05)。结论:雄激素与雌激素通过各自的受体发挥协调作用而共同促进精子发生。精子发生阻滞可能与包括雄激素受体、ERα及热休克蛋白90在内的一系列复杂的细胞信号转导障碍有关。     

睾丸生精小管界膜和管周肌样细胞调控睾丸功能

精子的发生除了受下丘脑-垂体-性腺轴分泌的激素调节外,还受到睾丸组织本身分泌的一些因子的调控.旁分泌是指某种组织中的一种细胞产生的因子作用于同一组织中的另一种细胞,从而起到调节靶细胞的功能.睾丸内多种细胞分泌的因子是通过旁分泌起作用的,可对精子发生进行更精细的调控.《美国实验生物学会联合会杂志》(FASEB Journal) 2009年12月刊上,Michelle Welsh等研究证实睾酮作用于睾丸中的另一类细胞——管周肌样细胞(peritubularmyoid,PTM)上的受体(AR),调控支持细胞的功能,进而调节精子形成.本文就界膜和管周细胞与旁分泌以及激素对精子的调控进行综述.     

Ccdc70基因在小鼠睾丸精子发生过程中的表达特征

目的:探讨Ccdc70(Coiled-coil domain containing 70)基因在小鼠睾丸中的表达特征并分析其在生精过程中的潜在功能。方法:经表达谱芯片筛选出小鼠睾丸特异性基因Ccdc70,通过RT-PCR、real-time PCR、Western印迹及免疫组化检测Ccdc70基因在成年小鼠睾丸中表达特征,并对该蛋白做相关的生物信息学分析。结果:RT-PCR、real-time PCR和Western印迹结果表明Ccdc70基因在小鼠睾丸中高表达,在附睾中低表达;免疫组化结果表明Ccdc70蛋白在睾丸中主要表达于小鼠精母细胞和圆形精子胞质,在附睾中主要表达在附睾管上皮细胞。生物信息学分析显示该蛋白存在一个CCDC结构域,并在哺乳动物进化过程中高度保守。结论:Ccdc70为小鼠睾丸高表达基因,且主要表达于精母细胞、圆形精子及附睾管上皮细胞,提示其可能参与调控小鼠精子发生过程及附睾精子的进一步成熟。     

胱蛋白酶抑制剂相关的附睾精子发生基因在不同发育阶段小鼠睾丸和附睾中的表达

目的 :研究胱蛋白酶抑制剂相关的附睾精子发生 (Cres)基因在生后不同发育阶段小鼠睾丸及附睾中的表达规律。　方法 :采用半定量RT PCR方法检测CresmRNA在生后 14、2 0、2 2、2 8、35、4 9、70、4 0 0d小鼠睾丸及附睾中的表达变化。　结果 :Cres基因在 14d小鼠睾丸和附睾中呈低水平表达 ,随着小鼠的生长发育 ,CresmRNA的表达量逐渐升高。在 70d小鼠睾丸和 4 0 0d小鼠附睾中 ,CresmRNA的表达量达到峰值。　结论 :Cres基因在生后不同发育阶段小鼠睾丸及附睾中呈现明显的规律性表达 ,可能参与精子发生、成熟过程的调控。     

激素对精子发生的调控

精子发生是一个连续不断的细胞增生与分化的过程 ,是激素依赖的调控 ,其中卵泡刺激素 (FSH)和黄体生成素 (LH)刺激释放的睾酮 (T)是主要的激素调节者。睾丸内T是维持精子发生最关健的因素之一 ,而FSH对正常精子发生的起始和维持同样是必须的。在介导激素调节中 ,Sertoli细胞处于核心地位。同时 ,正常精子发生过程中的生精细胞凋亡也是激素调控的。深入研究精子发生的激素调控 ,为探索安全、可复的男性避孕方法奠定了基础。     

胱蛋白酶抑制剂相关的附睾精子发生基因的调节和功能

CRES(cystatin relatedepididymalspermatogenic,胱蛋白酶抑制剂相关的附睾精子发生 )蛋白是胱蛋白酶抑制剂(cystatin)超家族中家族 2的一个亚类。然而 ,与cystatinC的广泛性表达不同 ,Cres基因只在分裂后的生殖细胞、附睾头部近端和腺垂体促性腺激素细胞中表达。cystatin对C1半胱氨酸蛋白酶抑制作用的发挥必须有 3个共有位点的参与 ,而CRES蛋白缺少其中的 2个位点。因此 ,CERS在生殖系统和神经内分泌系统中的功能也许是独特的和组织特异性的。本文概述了以下方面的研究 :①Cres基因启动子及其转录调节蛋白相关的可能对Cres的组织特异性表达有重要作用的DNA结合位点。②CRES蛋白的生物学功能。Norethern印迹法、凝胶转移分析和瞬时转染实验均表明 ,附睾和促性腺激素细胞中主要表达C EBP家族中的C EBPβ(CCAAT 增强子结合蛋白 ) ,且C EBPβ对于Cres基因在这两个组织中的高表达是必不可少的。另外 ,构建了表达氯霉素乙酰基转移酶 (CAT)报告基因的转基因小鼠 ,CAT报告基因由Cres基因 5′端 1 6kb的启动子所调控。分析显示 ,CATmRNA仅在生殖细胞中表达 ,说明Cres 5′端 1 6kb的侧翼区含有调控CAT在睾丸中表达的DNA序列 ,而缺乏指导CAT在附睾中表达的序列 ,或者此1 6kb的DNA片段存在Cres的负调节成分。最后 ,     

2058个小鼠精子发生相关基因的筛选与表达研究

目的 通过比较不同阶段的小鼠睾丸全基因组表达谱,筛选小鼠年龄依赖性表达基因.方法 采用Affymetrix全基因组表达谱芯片(版本号430.2),对日龄为4、9、18、35、54d和6月龄的小鼠睾丸组织进行全基因组表达差异分析.并采用半定量RT-PCR验证其差异表达基因.结果 经过比较,在9d和18d,18d和35d之间的小鼠睾丸基因表达谱之间,存在大量的差异表达基因,其中有2058个基因在小鼠6个日龄中表现为递增表达趋势,通过半定量RT-PCR验证了其中10个随机挑选的递增表达基因.文献检索发现目前已知功能的21个精子发生相关基因均在这2058个基因之中.因此,推测这2058个基因是小鼠精子发生相关基因.本文同时对这2058个基因的基因表达和功能分类进行了生物信息学分析.结论 本文筛选出小鼠精子发生相关基因2058个,并对其表达特征、功能分类进行了初步分析,这项研究提供了从分子水平识别小鼠睾丸组织精子发生相关基因的方法,有助于进一步阐述雄性哺乳动物生殖相关分子学基础.     

生殖激素受体与精子发生关系的研究进展

精子发生是一个非常复杂的过程,尤其受生殖激素调控。生殖激素与其受体结合在精子的发生、分化、成熟中起着至关重要的作用。因此了解精子发生过程中生殖激素受体的变化对精子发生障碍研究有着重要的价值。本文对生殖激素受体的基因突变及多态性与精子发生的关系进行综述,以期为男性不育的诊治提供帮助。     

染色体1;12平衡易位与精子发生相关性研究

目的 :对发现的不育伴染色体 1;12平衡易位的孪生兄弟进行研究 ,探讨与精子发生的关系。　方法 :对孪生兄弟进行染色体核型、精液常规、外周血激素测定和睾丸病理分析 ,并进行精子发生相关基因YRRM1、DAZ和DYS2 4 0位点的测定。　结果 :孪生兄弟的染色体核型均为 4 6 ,XY ,t(1;12 ) (q2 4 ;q2 4 ) ;精子密度 <1 0× 10 6/ml;外周血睾酮略低于正常 ,FSH和LH均正常 ;Y染色体长臂上的YRRM1、DAZ和DYS2 4 0基因未见缺失 ;睾丸病理分析显示生精阻滞 ,偶见精子。　结论 :染色体平衡易位t(1;12 ) (q2 4 ;q2 4 )可能是孪生兄弟精子发生障碍的原因 ,在染色体的断裂部位可能存在人精子发生相关基因     

A stereological study of the effects of experimental inguinal cryptorchidism and subsequent orchiopexy on spermatogenesis in adult monkeys

Our previous study demonstrated that experimental intra-abdominal cryptorchidism in adult rabbits for 13 weeks resulted in severe spermatogenic arrest: type A spermatogonia was the only germ cell type seen in the seminiferous epithelium and its number per testis was reduced by 84%. Seven weeks following orchiopexy, the type A spermatogonial number returned to the near-normal range in most animals and spermatogenesis partially recovered (Reproduction 2002, 124, 95-105). This study aimed to determine whether inguinal cryptorchidism would produce less-severe damage to spermatogenesis and whether subsequent orchiopexy would better restore spermatogenesis. Five normal adult male rhesus monkeys (Macaca mulatta) underwent bilateral artificial inguinal cryptorchidism. Half a year later, one testis together with the ipsilateral epididymis were removed from each animal and then unilateral orchiopexy was performed on the contralateral side, with the remaining testis and epididymis being removed another half a year later. A contemporary unbiased and efficient stereological tool, the optical disector, was used to estimate numbers of all types of spermatogenic cells in the testis and spermatozoa in the epididymis. Spermatogenic arrest was induced by cryptorchidism at the stage of spermatogonia (n = 1), spermatocytes (n = 2) or early spermatids (n = 1), with the type A spermatogonial numbers per testis being reduced to 14.8-57.2% of the control average; in one of the five cryptorchid animals, however, spermatogenesis remained normal. Subsequent orchiopexy, which was successfully performed on two animals with cryptorchidism-induced spermatogenic arrest, brought on a full or partial recovery of spermatogenesis. In conclusion, inguinal cryptorchidism induces less severe (in comparison with an intra-abdominal one) and variable damage to spermatogenesis, which is restored, at least in part, by subsequent orchiopexy.     

Identification of a novel testis-specific gene and its potential roles in testis development／spermatogenesis

Aim: To identify and characterize a novel gene with potential roles in testis development and spermatogenesis.Methods: A cDNA microarray was constructed from a human testis large insert cDNA library and hybridized with probes of human or mouse adult and fetal testes. Differentially expressed genes were isolated and sequenced. RT-PCR was used to test the tissue distribution of the genes of interest and in situ hybridization was performed to localize the gene expression in the mouse testis. A range of bioinformatical programs including Gene Runner, SMART, NCBI Blast and Emboss CpGPlot were used to characterize the new gene‘s feature. Results: A novel testis-specific gene,NYD-SPS, was differentially expressed in fetal and adult testes. The deduced protein structure of NYD-SP5 was found to contain an IQ motif (a short calmodulin-binding motif containing conserved lie and Gin residues), a Carbamate kinase-like domain, a Zn-dependent exopeptidase domain and a lactate dehydrogenase (LDH) C-terminal-like domain. RT-PCR analysis revealed that NYD-SP5 was predominantly expressed in the testis but not in other 15 tissues examined. In situ hybridization and RT-PCR examinations revealed that the expression of NYD-SP5 was confined in the male germ cell but not present in the somatic cell in the testes. Conclusion: NYD-SP5 is a newly found testisspecific gene with potential roles in testis development and spermatogenesis through a calmodulin-activated enzyme.     

A matter of death and life: the significance of germ cell death during spermatogenesis

The significance of cell death occurring during spermatogenesis is a subject of interest because of its potential medical importance. Unfortunately, the field has been difficult for andrologists to penetrate, in part because of the difficulties of studying germ cells in vitro and the complexity of designing suitable models in which to dissect the molecular signalling pathways involved in control of germ cell apoptosis. As a result, the reasons for these deaths remain unclear despite considerable investigative effort. As developments which have occurred over the last few years in understanding of apoptosis can shed light on this important topic, this review focuses on what is currently known about germ cell apoptosis and outlines the emerging picture of what might be the causes and biological role of germ cell deaths in spermatogenesis.     

Reversible effect of testosterone undecanoate injection on spermatogenesis in rats

Aim: To study the effect of testosterone undecanoate (TU) injection on spermatogenesis in rats. Methods: Twenty adult SD rats received vehicle or TU (8 mg/kg, 19 mg/kg or 025 mg/kg) injection, im, every 15 days for days, and another 38 animals received similar treatments for 130 days with half of them undergoing a recovery phase of 120 days (5 rats for each treatment). At the end of the treatment, testes were removed and the diameter of the seminiferous tubules and the number of late elongated spermatids ( steps 15 - 19 ) per testis were estimated with stereological methods as a measure of the spermatogenic efficiency. Results: Low dose (8 mg/kg) TU treatment virtually had no effect on spermatogenesis. A dose of 19 mg/kg slightly suppressed spermatogenesis 60 days after treatment, and severe suppression occurred after another 70 days of dosing. Spermatogenesis was completely recovered at the end of the recovery phase. Large dose (625 mg/kg) TU treatment did not significantly affect spermatogenesis and was well tolerated by animals. Conclusion: TU injection reversibly suppresses spermatogenesis in rats.     

Testicular testosterone concentration, interstitial cell density and spermatogenesis in infertile men

The concentration of testosterone was estimated in testicular biopsies taken from infertile men under general anaesthesia and was found to vary between 0.77 and 9.87 nmol/g wet tissue (median 3.41 nmol/g). Spermatogenesis was assessed by the Johnsen scoring technique but there was no evidence of a deficiency of intratesticular testosterone being associated with dysfunction of the seminiferous tubules. Similarly, there was no direct relationship with testicular size, clinical diagnosis, or the concentration of testosterone found in peripheral plasma taken at the same time as the testicular biopsy. These negative findings were not explained by variation in the volume densities of the Leydig cells assessed in 10 biopsies selected to be representative of the range of testosterone concentrations found in the entire series. A retrospective comparison between the concentration of testosterone in peripheral plasma at the time of surgery and the available preoperative levels found in 10 patients provided further evidence for the previously reported lowering of testosterone levels by general anaesthesia. It is suggested that future studies of testicular androgens should be conducted on tissue obtained under local anaesthesia in order to eliminate this effect.     

Effect of experimentally induced Escherichia coli epididymo-orchitis and ciprofloxacin treatment on rat spermatogenesis

We investigated the effects of epididymo-orchitis and ciprofloxacin on rat testicular histology and spermatogenesis. The control group underwent left orchiectomy. The second group received oral ciprofloxacin (150 mg/kg/day) for 10 days. Escherichia coli (10(6) cfu/mL, 0.1 mL) was injected into the proximal right ductus deferens in the third group. The fourth group received ciprofloxacin treatment 48 h after E. coli inoculation. In groups 3 and 4, bilateral orchiectomy was performed 14 days after the challenge. In healthy rats, ciprofloxacin caused recognizable histological damage associated with a mild decrease in testicular volume and sperm concentration. Infected testicles in groups 3 and 4 revealed severe histological damage associated with severe testicular atrophy and impaired spermatogenesis that were more significant in infected rats which received ciprofloxacin treatment. Contralateral testicles in these animals showed similar histopathological changes to a lesser extent. The results of our study suggest a gonadotoxic potential for ciprofloxacin and this potential in humans should be addressed with further studies.     

Effect of sodium arsenite on spermatogenesis,plasma gonadotrophins and testosterone in rats

To investigate the effect of arsenic on spermatogenesis. Methods: Mature (4 months old) Wistar rats were intraperitoneally administered sodium arsenite at doses of 4, 5 or 6 mg-kg^-day1 for 26 days. Different varieties of germ cells at stage VII seminiferous epithelium cycle, namely, type A spermatogonia (ASg), preleptotene spermatocytes (pLSc), midpachytene spermatocytes (mPSc) and step 7 spermatids (7Sd) were quantitatively evaluated, along with radioimmunoassay of plasma follicle-stimulating hormone (FSH), lutuneizing hormone (LH), testosterone and assessment of the epididymal sperm count. Results: In the 5 and 6 mg/kg groups, there were significant dose-dependent decreases in the accessory sex organ weights, epididymal sperm count and plasma concentrations of LH, FSH and testosterone with massive degeneration of all the germ cells at stage VII. The changes were insignificant in the 4 mg/kg group. Conclusion: Arsenite has a suppressive influence on spermatogenesis and gonadotrophin and testosterone r