Murugesan Palaniappan, Muthusamy Thirupathi, Balasubramanian Karundevi, Arunakaran Jagadeesan
Department of Endocrinology, Dr. ALM Post Graduate Institute of Basic Medical Sciences, University of Madras, Taramani Campus, Chennai 600113, India.
Reprod Toxicol. 2008 Aug;25(4):447-54. doi: 10.1016/j.reprotox.2008.04.003. Epub 2008 Apr 18.
Polychlorinated biphenyls (PCBs) are environmental contaminants that in humans and animals disturb normal endocrine functions including gonadal functions. The present studies were aimed at determining the direct effects of PCB on Leydig cell testosterone production and antioxidant system in vitro. Adult Leydig cells were purified by Percoll gradient centrifugation method and the purity of Leydig cells was also determined by 3beta-hydroxysteroid dehydrogenase (3beta-HSD) staining method. Purified Leydig cells were exposed to different concentrations (10(-10) to 10(-7) M) of PCB (Aroclor 1254) for 6 and 12 h under basal and LH-stimulated conditions. After incubation, the cultured media were collected and used for the assay of testosterone. The treated cells were used for quantification of cell surface LH receptors and activity of steroidogenic enzymes such as cytochrome P450 side chain cleavage enzyme (P450scc), 3beta-HSD and 17beta-hydroxysteroid dehydrogenase (17beta-HSD). In addition, Leydig cellular enzymatic antioxidants such as superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), gamma-glutamyl transpeptidase (gamma-GT), glutathione-S-transferase (GST) and non-enzymatic antioxidants such as vitamin C and E were assayed. Lipid peroxidation (LPO) and reactive oxygen species (ROS) were also estimated in Leydig cells. The results indicated that Aroclor 1254 (10(-8) and 10(-7) M) treatments significantly inhibit basal and LH-stimulated testosterone production. In addition to this, the activity of steroidogenic enzymes, enzymatic and non-enzymatic antioxidants were significantly diminished in a dose- and time-dependent manner. Moreover, the LPO and ROS were elevated in a dose- and time-dependent manner under basal and LH-stimulated conditions. These findings suggest that PCBs can act directly on Leydig cells to inhibit testosterone biosynthesis by reducing steroidogenic enzymes, enzymatic and non-enzymatic antioxidants.
多氯联苯（PCBs）是环境污染物，可干扰人类和动物的正常内分泌功能，包括性腺功能。本研究旨在确定PCB对体外睾丸间质细胞睾酮生成和抗氧化系统的直接影响。采用Percoll梯度离心法纯化成年睾丸间质细胞，并通过3β-羟基类固醇脱氢酶（3β-HSD）染色法测定睾丸间质细胞的纯度。在基础和促黄体生成素（LH）刺激条件下，将纯化的睾丸间质细胞暴露于不同浓度（10⁻¹⁰至10⁻⁷M）的PCB（氯丹1254）中6小时和12小时。孵育后，收集培养基用于睾酮测定。处理后的细胞用于定量细胞表面LH受体以及细胞色素P450侧链裂解酶（P450scc）、3β-HSD和17β-羟基类固醇脱氢酶（17β-HSD）等类固醇生成酶的活性。此外，还测定了睾丸间质细胞的酶促抗氧化剂，如超氧化物歧化酶（SOD）、过氧化氢酶（CAT）、谷胱甘肽过氧化物酶（GPx）、谷胱甘肽还原酶（GR）、γ-谷氨酰转肽酶（γ-GT）、谷胱甘肽-S-转移酶（GST）以及非酶促抗氧化剂，如维生素C和E。还评估了睾丸间质细胞中的脂质过氧化（LPO）和活性氧（ROS）。结果表明，氯丹1254（10⁻⁸和10⁻⁷M）处理显著抑制基础和LH刺激的睾酮生成。除此之外，类固醇生成酶、酶促和非酶促抗氧化剂的活性以剂量和时间依赖性方式显著降低。此外，在基础和LH刺激条件下，LPO和ROS以剂量和时间依赖性方式升高。这些发现表明，PCBs可直接作用于睾丸间质细胞，通过降低类固醇生成酶、酶促和非酶促抗氧化剂来抑制睾酮生物合成。
