## 4 Discussion
It should be noted that the decrease in the activity of the antioxidant enzymes SOD and GPO, under cold stress for eight weeks (chronic cold stress), was previously described for rat erythrocytes [39]. A similar effect during the year, activated SOD in the tissues of the myocardium and inhibited GPO [40]. Apparently, not only the duration of cold exposure is important, but also the analyzed tissue in which the activity of the antioxidant enzymes occurs. For example, swimming for eight weeks led to the activation of SOD in the brain [41]. In our study, we analyzed SOD and GPO in the liver and the heart, allowingus to assume a relationship between a decrease in the activity of antioxidant enzymes and the activation of cytolysis processes, which are indirectly evidenced by enzymes such as ALT and AST, as well as their ratio. It should be noted that the set of enzymes studied by us in this work is used in a number of studies, to determine the degree of adaptation of rats to physical exertion [32; 33; 34]. The ratio of enzyme activity also shows the endurance of animals and their fitness [42]. It should be noted the enzyme gamma-butyrobetaine hydroxylase inhibitor is often used to enhance physical performance. An increase in sports performances has been shown in athletes [28] and test animals [43; 44] who are under the influence of this drug; however, its use for athletes has been currently prohibited by WADA [45]. One of the arguments for the ban was the long-term persistence of the active substance in human tissues [46]. It should be noted that the drug was developed in the former USSR and was used for a long time to stimulate physical performance. The correctness of the organization of clinical trials of the drug is discussed [47]. Despite the ban on the use of the drug in people in sports, the study of its neuroprotective effects continues [48]. In testing rats, the enzyme gamma-butyrobetaine hydroxylase inhibitor has a cytoprotective effect against toxic effects [49]. The hepatoprotective and cardioprotective properties of the compound have been shown [50]. The cardioprotective effects of drugs have been described in modeling experimental myocardial ischemia [51]. In experimental ischemia of the central nervous system, the enzyme gamma-butyrobetaine hydroxylase inhibitor has antioxidative and neuroprotective effects [46; 52]. The mechanisms of drug action are not fully explored, and its pharmacokinetics are highly variable [53], which complicates the practical use of the enzyme gamma-butyrobetaine hydroxylase inhibitor. Therefore, there is a constant search for other adap-togens, including those on a plant basis. For example, in rats swimming, an increase in the activity of antioxidant enzymes is shown under the influence of Chrysanthellum americanum extract [54]. Earlier, it was found that Eleutherococcus had an anti-ischemic effect on test animals [55]. Under chronic stress exposure of rats, the extracts of this plant normalized the homeostasis parameters [56]. It was shown that a complex phytopreparation, containing Eleutherococcus, had a cardioprotective effect [20]. Unfortunately, a large number of publications on Eleutherococcus are written in Russian, and are not available to the general scientific community. Therefore, a separate review was published on the analysis of the Russian-language literature on this phytopreparation [25], which may contribute to the wider use of Eleutherococcus in experimental and clinical studies. Ligusticum wallichii is traditionally used in Chinese medicine. A systematic review of animal research revealed antioxidant, cytoprotective, and other properties of extracts of this plant [14]. The effect of Ligusticum wallichii preparations on the expression of Toll-like receptors in rat hepatocytes has been shown [57]. When modeling myocardial ischemia, the extracts of this plant have an antioxidant effect [58]. However, for one of the active compounds isolated from the plant, tetramethylpyrazine, long-term side effects on the myocardium have been described.