High-fat diets (HFDs) are detrimental to steroidogenesis and male fertility. This study aimed to investigate the protective effects of melatonin (MT) treatment on testicular dysfunction in mice fed with HFD. C57BL/6J male mice were randomly divided into three groups: CTRL, HFD and HFD + MT. MT treatment mitigated the increase in body weight and adipose tissue in HFD-fed mice. Serum levels of sex hormones were improved upon MT supplementation, and the expression of the testosterone synthesis proteins, StAR and P450scc was rescued as well. MT treatment significantly up-regulated the expression of SIRT1, SOD2, and GPx4 and down-regulated the expression of GRP78 and CHOP, indicating an attenuation of oxidative stress (OS) and endoplasmic reticulum (ER) stress. In TM3 cells, MT treatment protected against H 2 O 2 -induced steroidogenic collapse by improving mitochondrial function and attenuating OS and ER stress. These results indicate that MT treatment can improve steroidogenesis in mice fed with HFD and may have therapeutic value in the treatment of obesity-associated hypogonadism. K E Y W O R D Shigh-fat-diet, Leydig cells, melatonin, oxidative stress, steroidogenesis

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In recent years, resveratrol has been shown to protect against metabolic damage, including obesity-associated subfertility/infertility. In the present study, proteomic alterations in testicular tissues were investigated by tandem mass tag (TMT) in mice fed with a high-fat diet (HFD) without or with resveratrol supplementation (HFD+RSV). Serum testosterone levels, spermatozoa parameters and testicular histological morphology were assessed. Resveratrol treatment was shown to significantly reduce serum cholesterol, prevent the HFD-induced reductions in serum testosterone and spermatozoa parameters, and decrease the ultrastructural degeneration of testicular tissues. The comparative proteomics analysis revealed 58 differentially expressed proteins between the HFD and control groups and 38 differentially expressed proteins between the HFD and HFD+RSV groups. Gene ontology (GO) term enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis revealed that the most highly enriched differential proteins were correlated to spermatozoa function and cholesterol metabolism. The real-time RT-PCR and western blotting results confirmed the differential expression of the corresponding proteins related to spermatozoa function that were identified by proteomics. The present study provides new insight into the mechanisms of the beneficial effects of resveratrol, and may present it as a potential therapeutic strategy for obesity-associated male subfertility/infertility.

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Objectives: Low back pain (LBP) has negative implications for the military's combat effectiveness. This study was conducted to determine the prevalence and risk factors of LBP among pilots through a questionnaire and physical function assessments.Methods: Data on the demographic and occupational characteristics, health habits, physical activity, and musculoskeletal injuries of 217 male pilots (114 fighter, 48 helicopter, and 55 transport pilots) were collected using a self-reported questionnaire and physical function assessments.Results: LBP prevalence was 37.8% in the total cohort and 36.0, 45.8, and 34.5% among fighter, helicopter, and transport pilots, respectively. Multivariate regression analysis revealed that the risk factors significantly associated with LBP were neck pain [odds ratio (OR): 3.559, 95% confidence interval (CI): 1.827–6.934], transversus abdominis activation (OR: 0.346, 95% CI: 0.172–0.698), and hip external rotator strength (OR: 0.001, 95% CI: 0.000–0.563) in the total cohort; neck pain (OR: 3.586, 95% CI: 1.365–9.418), transversus abdominis activation (OR: 0.268, 95% CI: 0.094–0.765), hip external rotator strength (OR: 0.000, 95% CI: 0.000–0.949), and weekly flying hours (OR: 3.889, 95% CI: 1.490–10.149) in fighter pilots; irregular strength training (OR: 0.036, 95% CI: 0.003–0.507) and hip external rotator strength (OR: 0.000, 95% CI: 0.000–0.042) in helicopter pilots; and neck pain (OR: 6.417, 95% CI: 1.424–28.909) in transport pilots.Conclusions: High volume flight schedules and weak core muscle functions have significant negative effects on pilots' back health. LBP is commonly associated with high weekly flying hours, worsening neck pain, transversus abdominis insufficient activation, and reduced hip extensor/rotator strength. Risk factors vary among pilots of different aircraft. Thus, specific core muscle training would be especially important for military pilots.