Alpha- and gamma-tocopherol levels in human semen and their potential functional implications.

Vitamin E is a potent antioxidant that has been considered involved in fertility, but studies have mostly focused on α-tocopherol. Our study aimed at measuring, by an isotope dilution gas chromatography-mass spectrometry method, α- and γ-tocopherol concentration in human semen in a large and well-characterised population (134 men with different semen parameters and in varicocele patients), as well as their potential role in male fertility. We carried out freeze/thaw experiments in 15 samples with the two isomers in the cryoprotective medium. Moreover, our study included 10 subjects supplemented in vivo with α-tocopherol for 90 days. In seminal plasma, γ-tocopherol concentration was significantly lower in the varicocele group than in the normozoospermic group. We observed that γ-tocopherol, supplemented to cryopreservation medium, induced a higher post-thaw human sperm viability and motility than α-tocopherol. The results of in vivo α-tocopherol supplementation showed a decrease in γ-tocopherol concentration with increasing α-tocopherol level in blood. This is the first report related to γ-tocopherol distribution in human semen analysed by gas chromatography-mass spectrometry. γ-tocopherol would not seem to be related to semen parameters but to cellular oxidative condition. This tocopherol may contribute to human health in a yet unexplored way.

Effects of dietary fatty acids and cholesterol excess on liver injury: A lipidomic approach.

Lipid accumulation is the hallmark of Non-alcoholic Fatty Liver Disease (NAFLD) and has been suggested to play a role in promoting fatty liver inflammation. Previous findings indicate that during oxidative stress conditions excess cholesterol autoxidizes to oxysterols. To date, the role of oxysterols and their potential interaction with fatty acids accumulation in NASH pathogenesis remains little investigated. We used the nutritional model of high fatty acids (HFA), high cholesterol (HCh) or high fat and high cholesterol (HFA+FCh) diets and explored by a lipidomic approach, the blood and liver distribution of fatty acids and oxysterols in response to dietary manipulation. We observed that HFA or HCh diets induced fatty liver without inflammation, which was otherwise observed only after supplementation of HFA+HCh. Very interestingly, the combination model was associated with a specific oxysterol fingerprint. The present work provides a complete analysis of the change in lipids and oxysterols profile induced by different lipid dietary model and their association with histological alteration of the liver. This study allows the generation of interesting hypotheses on the role of interaction of lipid and cholesterol metabolites in the liver injury during NAFLD development and progression. Moreover, the changes in the concentration and quality of oxysterols induced by a combination diet suggest a novel potential pathogenic mechanism in the progression from simple steatosis to steatohepatitis.