A Mechanism Study On Hypothyroidism-induced Reproductive Insult In Male Rats

Objective To explore the effect of hypothyroidism on reproductive system and its molecular mechanisms in male rats by establishing hypothyroidism animal model.Methods (1) Twenty male Wistar rats, weighing200-240g, were randomly divided into two groups, including control group exposured to normal saline solution and experimental group (hypothyroidism group) intragastrically treated with0.1%propylthiouracil solution for60days. Body weight of rats were weighed every3days. All rats were sacrificed after the last intragastric administation. The body and relative teste weights were calculated.(2) The levels of triiodothyronine (T3), thyroxine (T4) and thyroid stimulating hormone (TSH) and testosterone (T) and estradiol (E2) in serum were detected by radioimmunoassay.(3) The average path velocity (VAP), straight line velocity (VSL), straightness (STR), amplitude of lateral head displacement (ALH), spermdensity (p), curvilinear velocity (VCL), linearity (LIN), wobble (WOB), mean angular deviation (MAD) and beat cross frequency (BCF) were measured by WLJY-9000color-detection system.(4) The activities of superoxide dismutase (SOD), catalase (CAT), nitricoxide synthase (NOS) and the contents of malondialdehyde (MDA) and hydrogen peroxide (H2O2) and nitrogen monoxidum (NO) in testis tissue were determinded by spectrophotometric assay.(5) The contents of calcium (Ca) and magnesium (Mg) and zinc (Zn) were detected by atomic absorption spectrometry.(6) The expression of c-fos gene at protein and mRNA level were measured by Western Blottiing and Real-time fluorescence quantitative PCR (qPCR) techniques.Results (1) The body weights in hypothyroidism group on30th day and60th day were significantly decreased (P<0.05) and testis organ coefficient in hypothyroidism group was decreased (P<0.05) compared with control group.(2) The level of T3and T4in hypothyroidism group were significantly decreased (P<0.05), the level of TSH was significantly increased (P<0.05).(3) The content of T in hypothyroidism group was decreased (PO.05), the level of E2in hypothyroidism group was significantly increased (P<0.05).(4) The average path velocity, straightness, and linear velocity and forward and side swing amplitude in hypothyroidism group were significantly increased (P<0.05), sperm density significantly was decreased (P?<0.05), curvilinear velocity and linear and swing and moving average angle and beat frequency did not have significantly different (P>0.05).(5) The activities of catalase (CAT), nitricoxide synthase (NOS) and superoxide dismutase (SOD) in hypothyroidism group were significantly decreased (P<0.05), the content of MDA and H2O2were significantly increased (P<0.05), the NO content was significantly decreased (P<0.05).(6) The content of Ca and Zn in hypothyroidism group were significantly decreased (P<0.05), there were no significant differences in the content of Mg between hypothyroidism group and control group (P>0.05).(7) The protein and mRNA expression level of c-fos in hypothyroidism group was significantly decreased (P<0.05).Conclusions The results suggest that hypothyroidism can lead to reproductive toxicity in male rats, and is in part related to the alteration in hormone level, sperm motility parameters and the content of Ca, Mg and Zn, and the antioxidant ability and the content of NO and the activity of NOS of testicular tissue, and the protein and mRNA expression levels of c-fos.