Li Chunmei, Taneda Shinji, Suzuki Akira K, Furuta Chie, Watanabe Gen, Taya Kazuyoshi
Department of Basic Veterinary Science, United Graduate School of Veterinary Sciences, Gifu University, Gifu, Japan.
J Androl. 2007 Mar-Apr;28(2):252-8. doi: 10.2164/jandrol.106.000802. Epub 2006 Oct 4.
We investigated the effects of 3-methyl-4-nitrophenol (4-nitro-m-cresol, PNMC) isolated from diesel exhaust particles (DEP) on the reproductive functions of male rats. Twenty-eight-day-old rats were injected subcutaneously with PNMC (1, 10, or 100 mg/kg) daily for 5 days. The weights of the epididymis, seminal vesicle, and Cowper gland were significantly decreased in rats treated with 10 mg/kg PNMC. The plasma concentrations of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were significantly increased by PNMC at 100 mg/kg. However, the plasma concentrations of testosterone and immunoreactive (ir)-inhibin were significantly decreased by PNMC at 100 mg/kg. The testosterone content of the testicles was significantly decreased in the group treated with 100 mg/kg PNMC compared with the control group. Furthermore, testicular concentration of ir-inhibin was significantly decreased by PNMC at 1 mg/kg or 100 mg/kg. To investigate the direct effects of PNMC on the secretion of LH and FSH from the anterior pituitary gland, and on the secretion of testosterone from the testes, we exposed cultured anterior pituitary and interstitial Leydig cells to PNMC (10(-6), 10(-5), 10(-4) M) with or without gonadotropin-releasing hormone (GnRH; 10 nM) (for the LH and FSH tests) and human chorionic gonadotropin (hCG; 0.1 IU/mL) (for the testosterone test) for 24 hours. PNMC did not change either the basal or GnRH-stimulated levels of FSH and LH secretion. However, PNMC significantly inhibited both basal and hCG-stimulated testosterone production. These findings suggest that PNMC has a direct effect on the testes of immature male rats, causing a reduction in testosterone secretion.
我们研究了从柴油尾气颗粒（DEP）中分离出的3-甲基-4-硝基苯酚（4-硝基间甲酚，PNMC）对雄性大鼠生殖功能的影响。28日龄大鼠每天皮下注射PNMC（1、10或100 mg/kg），持续5天。用10 mg/kg PNMC处理的大鼠附睾、精囊和考珀腺的重量显著降低。100 mg/kg的PNMC使促黄体生成素（LH）和促卵泡激素（FSH）的血浆浓度显著升高。然而，100 mg/kg的PNMC使睾酮和免疫反应性（ir）抑制素的血浆浓度显著降低。与对照组相比，100 mg/kg PNMC处理组的睾丸睾酮含量显著降低。此外，1 mg/kg或100 mg/kg的PNMC使睾丸中ir抑制素的浓度显著降低。为了研究PNMC对垂体前叶LH和FSH分泌以及睾丸睾酮分泌的直接影响，我们将培养的垂体前叶和睾丸间质Leydig细胞暴露于PNMC（10⁻⁶、10⁻⁵、10⁻⁴ M），同时添加或不添加促性腺激素释放激素（GnRH；10 nM）（用于LH和FSH测试）以及人绒毛膜促性腺激素（hCG；0.1 IU/mL）（用于睾酮测试），处理24小时。PNMC既未改变FSH和LH分泌的基础水平，也未改变GnRH刺激后的水平。然而，PNMC显著抑制了基础和hCG刺激后的睾酮生成。这些发现表明，PNMC对未成熟雄性大鼠的睾丸有直接影响，导致睾酮分泌减少。
