Ruwanpura Saleela M, McLachlan Robert I, Matthiesson Kati L, Meachem Sarah J
Prince Henry's Institute, Clayton, Level 4, 43-51 Kanooka Grove, Victoria 3168, Australia.
Hum Reprod. 2008 Feb;23(2):403-11. doi: 10.1093/humrep/dem376.
Gonadotrophins support spermatogenesis via poorly understood mechanisms. We aimed to determine the effect of FSH/LH suppression in regulating germ cell apoptosis and proliferation in normal fertile men.
Testicular tissues were obtained after gonadotrophin suppression induced by testosterone alone or combined with depot medroxyprogesterone acetate for 2 or 6 weeks and an untreated group of men (referred to as 'normal men') served as controls (n = 5 or 10 men per group). Apoptosis and proliferation were identified by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling (TUNEL) and proliferating cell nuclear antigen (PCNA) labelling methods, respectively. Intrinsic and extrinsic apoptotic pathways were identified by immunohistochemistry using the pathway-specific proteins: activated caspase (aCaspase) 9 and 8 and quantified using stereological techniques.
By 2 and 6 weeks, the proportion of TUNEL-labelled spermatogonia increased to 354% and 268% respectively, compared with normal men (P < 0.001), with increased caspase 9 [223 and 166% compared with normal men (P < 0.001)], but no increase in caspase 8, immunoreactivity. At 6 weeks, the proportions of TUNEL-labelled spermatocytes and round spermatids tended to increase (303 and 180% compared with normal men, NS), as did caspase 9 (199 and 147% compared with normal men, NS) and caspase 8 immunoreactivities (286 and 243% compared with normal men, NS and P = 0.06), respectively. The proportion of TUNEL-labelled elongating/elongated spermatids tended to increase (144 and 138% compared with normal men, NS) at 2 and 6 weeks, respectively, with no change in either caspase immunoreactivities. Even though the number of PCNA-labelled cells did not change with gonadotrophin suppression, the balance between proliferation and apoptosis was lower in spermatogonia (P = 0.01) and spermatocytes (P = 0.3) between treated and untreated normal men.
We demonstrated that gonadotrophins act as spermatogonial survival factors via the regulation of intrinsic apoptotic pathway, whereas having no effect of cellular proliferation in normal men.
促性腺激素通过尚不明确的机制支持精子发生。我们旨在确定抑制促卵泡生成素（FSH）/促黄体生成素（LH）对正常生育男性生殖细胞凋亡和增殖的调节作用。
单独使用睾酮或联合醋酸甲羟孕酮长效注射剂抑制促性腺激素2周或6周后获取睾丸组织，未接受治疗的男性组（称为“正常男性”）作为对照（每组5或10名男性）。分别通过末端脱氧核苷酸转移酶介导的dUDP缺口末端标记法（TUNEL）和增殖细胞核抗原（PCNA）标记法鉴定凋亡和增殖情况。使用通路特异性蛋白活化半胱天冬酶（aCaspase）9和8通过免疫组织化学鉴定内在和外在凋亡途径，并使用体视学技术进行定量分析。
到2周和6周时，与正常男性相比，TUNEL标记的精原细胞比例分别增加到354%和268%（P<0.001），半胱天冬酶9增加[与正常男性相比分别为223%和166%（P<0.001）]，但半胱天冬酶8免疫反应性未增加。在6周时，TUNEL标记的精母细胞和圆形精子细胞比例趋于增加（与正常男性相比分别为303%和180%，无显著性差异），半胱天冬酶9（与正常男性相比分别为199%和147%，无显著性差异）和半胱天冬酶8免疫反应性（与正常男性相比分别为286%和243%，无显著性差异和P = 0.06）也分别增加。在2周和6周时，TUNEL标记的延长/延长型精子细胞比例分别趋于增加（与正常男性相比分别为144%和138%，无显著性差异），两种半胱天冬酶免疫反应性均无变化。尽管PCNA标记的细胞数量在促性腺激素抑制后没有变化，但在接受治疗和未接受治疗的正常男性之间，精原细胞（P = 0.01）和精母细胞（P = 0.3）的增殖与凋亡平衡较低。
我们证明，促性腺激素通过调节内在凋亡途径作为精原细胞存活因子，而对正常男性的细胞增殖没有影响。
