Defining sex differences in selected lipid metabolites of blood plasma in Wistar rats.

There is an increasing attention to the role that sex/gender plays in health, behavior and outcomes. Even though we know that males and females are not the same, experiments have sometimes been carried out without considering sex in scientific research. It is essential for scientists and clinicians to consider sex differences as one of the underlying physiological determinants of health and disease to provide the building blocks for evidence-based, individualized medicine. Our work aimed to reveal sex-associated differences in lipid metabolite levels of adult female (n = 10) and male (n = 10) Wistar rats, aged 60 days. Partial least square determination analysis (PLS-DA) method and a variance importance in projection (VIP) score was used to identify the key sex-specific metabolites. Our results show that all groups of lipid metabolites: lysophosphatidylcholines (lysoPCs), phosphatidylcholines (PCs), and sphingomyelins (SMs) show a significant sex-dependent pattern. According to our results, more than a half of lysoPCs studied showed sex-specific features. PCs and lysoPCs tend to be significantly elevated in the blood plasma of females. The most distinct increase in more than 90% of SMs has been revealed in female blood plasma, compared with males. According to VIP score, the most important feature was the metabolite PC aa C38:4. Our study points out a sex dimorphism in lipid metabolism. The identification of main lipid features may play a key role in preclinical and clinical practice.