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Summary Introduction: Rhodiola rosea (RR) and Rhodiola kirilowii (RK) are well known for their influence on central nervous system, however their impact on the development of alcohol tolerance has not yet been proven. Objective: The aim of this study was to determine the ability of RR and RK roots extracts to inhibit the development of alcohol tolerance in vivo, both, peripheral (metabolic) and central ones. Methods: Male Wistar rats were treated with RR and RK extracts (p.o.) and ethanol (i.p.) for ten consecutive days. On the first, third, fifth and eighth days the hypothermic action of ethanol was measured, while on the ninth day the loss of righting reflex was examined. On the tenth day rats were treated with assigned extract and sacrificed 1 h after the ethanol injection. Results: Both extracts inhibited development of tolerance to the hypothermic action of ethanol. The observed effect seems to be specific since none of the extracts affected body temperature in water-treated animals. RK extract also prolonged the hypnotic action of ethanol. RR-treated rats had higher blood-ethanol concentrations, in contrast to RK ones. Conclusions: RR and RK extracts inhibited the development of tolerance to the hypothermic action of ethanol. Prolongation of the hypnotic action of ethanol by RK extract may be associated with influence on the central nervous system, while the RR one also inhibited the development of metabolic tolerance.

Summary Introduction: In recent years, the search for potential neuroprotective properties of salidroside and its ability to influence the activity of nervous system become the subject of intense studies of many research groups. None of these studies, however, include an attempt to determine the effect of salidroside on the course of alcohol tolerance in vivo. Objective: The aim of this study was to investigate the ability of salidroside to inhibit the development of alcohol tolerance in rats, determining whether the effect of its action may occur in a dose-dependent manner, reducing both metabolic and central tolerance without affecting body temperature in control rats. Methods: Male Wistar rats were injected daily with ethanol at a dose of 3 g/kg for 9 consecutive days to produce ethanol tolerance. Salidroside in two doses (4.5 mg/kg and 45 mg/kg b.w.) or vehiculum was administered orally. On the 1st, 3rd, 5th and 8th day a hypothermic effect of ethanol was measured, while the loss of righting reflex procedure was performed on the 2nd, 4th, 6th and 7th day. On the 9th day rats were treated with salidroside, sacrificed 1 h after ethanol injections and blood was collected for blood-ethanol concentration measurement. Results: Salidroside at a dose of 45 mg/kg inhibited the development of tolerance to hypothermic and sedative effects of ethanol, whereas insignificant elevation of blood-ethanol concentration was observed. The dose of 4.5 mg/kg b.w. had minimal effect, only small inhibition of tolerance to hypothermic action was observed. Salidroside affected neither body mass growth nor body temperature in non-alcoholic (control) rats. Conclusions: Results of the study indicate that salidroside at a dose of 45 mg/kg inhibited the development of tolerance to the hypothermic effect of ethanol. Observed inhibition of tolerance to the sedative effect of ethanol seems to be associated with salidroside influence on the central nervous system. A comprehensive explanation of the abovementioned observations requires further pharmacological and pharmacodynamic studies.