# Comparative Analysis of Fatty Acids Concentration in Liver and Muscle Tissues of Rats and Mice
## 4 Discussion
This hypothesis may be supported by the fact that the enzymatic function of SCD1 contributes to the lipogenesis of palmitoleic acid (PA; C16:1), which exhibited significantly greater levels in mice muscle and liver tissue compared to rats. Different levels of FAs in the same organs of the tested animals may significantly differentiate the results obtained in studies of oxidative processes. An interesting example is DHA, the most susceptible to peroxidation fatty acid, 320 times more prone to peroxidation compared to OA and 8 times more susceptible than the LA [4,30]. It is important to note whether there exists a particular fatty acids content pattern in selected organs, with species-specific characteristics that render them more susceptible to peroxidation than others. The mechanisms by which oxidative stress induces lipotoxicity remain incompletely elucidated. Thus far, the predominant observations regarding lipotoxicity in cells have primarily implicated apoptosis as the principal mechanism of cell death [31, 32, 33]. Nevertheless, a novel mode of controlled cellular death has been elucidated more recently, termed ferotroposis [34]. This distinctive cellular death process entails the formation of hydroperoxides within the PUFA side chains of membrane lipids, facilitated by reactive oxygen species (ROS) and iron dependency [35,36]. This mechanism affects the cellular membranes' integrity and eventually executes ferroptosis [37]. Multiple scientific evidence points to the fact that a higher content of exogenous PUFA increases the sensitivity of cells to ferroptosis, whereas increased MUFA content acts against the mechanisms triggering ferroptotic cell death [38]. In this study, we showed a significant difference in the proportion of liver SFAs derived from NL, where in rat liver their levels were significantly higher compared to mice. In addition, rat liver also exhibited higher concentrations of some SFAs, particularly myristic acid (C:14), stearic acid (C:18), and tricosanoic acid (C:23), when compared to mice liver. The results of our study are consistent with others' studies, that indicate significant interspecies differences as well as in inter-organ variations in the composition of fatty acids [4,10,13,39,40]. Significantly higher levels of SFAs derived from NPL in the liver of rats may indicate a greater susceptibility to induction of lipotoxicity or NAFLD (non-alcoholic fatty liver disease). Saturated and unsaturated fatty acids exhibit notable differences in their respective impacts on lipotoxicity. Prior investigations conducted in Chinese hamster ovary cells, cardiac myocytes, pancreatic \(\beta\)-cells, breast cancer cell lines, and hematopoietic precursor cell lines collectively propose that the phenomenon of lipotoxicity, resulting from the buildup of long-chain fatty acids, is either selective to or exacerbated by saturated fatty acids [41, 42, 43, 44]. Our findings are relevant for studies focusing on lipid metabolism and its implications in diseases such as diabetes and metabolic disorders studied in mice or rats models. The significant difference between mice and rats in the FAs derived from NPL and PL fractions of skeletal muscle and liver indicated the species-specific metabolic characteristics. We suggest that the differences we described in the presented article might affect how skeletal muscle and liver responds to metabolic stress, exercise, and diet, impacting overall energy metabolism and possibly disease susceptibility or resilience.