1.Lipid Ratios And Testosterone In Men With Type 2 Diabetes Mellitus 2.Effect And Mechanism Of Palmitic Acid On Testosterone Synthesis In Mouse Leydig Cells TM3

[Background] Serum lipids have a close relation with testosterone. The serum lipids include total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), et al. It has been reported that testosterone is negatively correlated with TG, and positively correlated with HDL-C. Obesity and dyslipidemia are risk factors to testosterone. FFAs are stored as TGs in cytosolic droplets, they constitute an important source of fuel for organization to utilize. However, an excessive accumulation of lipids in ectopic sites may lead to numerous important pathologies associated with diabetes, hypertensiona and fatty liver. It has been studied that FFAs can induce cells dysfunction by endoplasmic reticulum, oxidative stress, apoptosis and inflammation pathway, which lead to a phenomenon known as lipotoxicity. But how FFAs effect testosterone synthesis have still unknown.Part 1.Lipid ratios and testosterone in men with type 2 diabetes mellitus[Objective] To assess the relationship between lipid ratios and total testosterone in a simple of men with type2 diabetes mellitus.[Methods] A total of 125 male subjects with type 2 diabetes mellitus were included. Total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), total testosterone (TT), follicle stimulating hormone (FSH), luteinizing Hormone (LH) were measured, then non-high-density lipoprotein cholesterol (nonHDL-C), lipid ratios including TG/HDL-C ratio, TC/HDL-C ratio and LDL-C/HDL-C ratio, non-HDL-C/HDL-C ratio and testosterone secretion index (TSI) were calculated. The subjects were divided into dyslipidemia group and normal lipidemia group to observe characteristics; the associations between the different lipid ratios and TT were assessed using correlation analysis and regression analysis methods. One-way ANOVA was used to compare the TT levels among TG/HDL-C groups divided by quartile. The areas of curve (AUC) of the receiver operating characteristic curve (ROC) were used to compare the power of the markers to identity the androgen deficiency (AD).[Results] Compared with normal lipidemia group, the dyslipidemia group had higher lipid ratios, p< 0.001, and TG/HDL-C ratio was signaficantly negatively correlated with TT. TT was significantly lowest in Q4 group, p< 0.001. ROC analysis showed that the AUCs of TG/HDL-C ratio was 0.754 [95% CI= 0.74-0.76].[Conclusion] TG/HDL-C ratio in men with type 2 diabetes mellitus is negatively correlated with TT, suggesting that TG/HDL-C ratio may be a risk factor for androgen in male with type 2 diabetes, and the TG/HDL-C ratio is a marker for identifying AD in type 2 diabetes mellitus. the associations between the different lipid ratios and TT were assessed using correlation analysis and regression analysis methods. One-way ANOVA was used to compare the TT levels among TG/HDL-C groups divided by quartile. The areas of curve (AUC) of the receiver operating characteristic curve (ROC) were used to compare the power of the markers to identity the androgen deficiency (AD).[Results] Compared with normal lipidemia group, the dyslipidemia group had higher lipid ratios, p< 0.001, and TG/HDL-C ratio was signaficantly negatively correlated with TT. TT was significantly lowest in Q4 group, p< 0.001. ROC analysis showed that the AUCs of TG/HDL-C ratio was 0.754 [95% CI= 0.74-0.76].[Conclusion] TG/HDL-C ratio in men with type 2 diabetes mellitus is negatively correlated with TT, suggesting that TG/HDL-C ratio may be a risk factor for androgen in male with type 2 diabetes, and the TG/HDL-C ratio is a marker for identifying AD in type 2 diabetes mellitus.Part 2. Effect and mechanism of palmitic acid on testosterone synthesis in mouse Leydig cells TM3[Objective] To investigate the effect of palmitic acid (PA) on testosterone synthesis in mouse Leydig cells (TM3) and to explore the potential mechanism.[Methods] When the cells were grown into approximately 70% confluency, fresh media containing increasing concentration of palmitic acid (0.2,0.4 mmol/L) was added for 48h. At the end of the incubation, the media was removed and the cells were then stimulated for another 4h with lU/ml human chorionic gonadotropin (hCG) in serum-free medium. The cell viability was detected by MTT. The intracellular accumulation of lipids was evaluated by Oil Red O staining. The amount of total cholesterol in leydig cells was measured by using the total cholesterol reagent kit. Chemiluminescence assay was used to determine the concentration of testosterone (T) in culture supernatant. The expression levels of steroidogenic acute regulatory protein (StAR) were measured by RT-PCR, western blot. The generation of reactive oxygen species (ROS) was measured using DCFH-DA, and the NO production was immediately assessed by measuring the amount of nitrite and nitrate in the cells using the total NO assay kit.[Results] (1) PA inhibited the cell viability of TM3 at some extent, but no significant inhibition was observed. (2) PA inhibited testosterone production in a dose-dependent manner. (3)The result implicated that there were lots of lipid droplets in PA overexpose group. The TC increased with the dose effect of PA. (4) Compared with OmM group, the mRNA and protein levels were significantly inhibited in PA treated groups, and the generation of ROS and NO was increased in PA groups.[Conclusion] PA can efficiently inhibit the steroidogenesis in mouse leydig cells (TM3), and decrease the expression of StAR. The machanism might relate to oxidative stress.