The effects of nicotine-and tar-free cigarette smoke extract on Leydig cells injury by oxidative stress and plasma testosterone level in rats

Abstract

Objective To evaluate the effects of nicotine-and tar-free cigarette smoke extract on Leydig cells injury by oxidative stress and plasma testosterone level in rats.Methods Thirty male Sprague-Dawley (SD) rats were randomly divided into 3 groups (n =10):the control group (PBS group),nicotine-and tar-free cigarette smoke extract (CSE) group and antioxidant group [CSE + glutathione (GSH) group].After sixty days,the levels of plasma testosterone (T),luteinizing hormone (LH),and follicle-stimulating hormone (FSH) were measured with radioimmunoassay,the activity of testicular tissue superoxide dismutase (SOD) was measured by xanthine oxidase essay and malonic dialdehyde (MDA) was examined by thiobarbituric acid method,and pathologic changes of the testicular tissue were observed under light microscope and electron microscope.Results Histologic examination of the testes revealed no significant change in the morphology and number of Leydig and sperm cells,however,many swollen mitochondria with mitochondrial cristae disappeared,and lysosome were found in Leydig cells by electron microscope in nicotine-and tar-free cigarette smoke extract (CSE) group.The levers of T [(2.58 ± 0.81) μg/L],SOD [(28.28 ± 1.27) U/(mg· prot)] in CSE group were more significantly reduced and MDA [(0.65 ± 0.070) U/(mg· prot)] increased than those in PBS group [T (6.02 ± 0.75) μg/L,SOD (38.07 ± 1.39),MDA (0.50 ± 0.066) U/(mg· prot)] (P ＜ 0.05),but there was no statistically significant difference with the serum levels FSH and LH (P ＞ 0.05).The difference between the control group and antioxidant group was not significant.Conclusion The effects of nicotine-and tar-free cigarette smoke extract on Leydig cells injury and plasma testosterone level are related to oxidative stress. Key words: Nicotine-and tar-free cigarette smoke extract; Oxidative stress; Leydig cells; Plasma testosterone