Characterization of the Anxiolytic Activity of Nunavik Rhodiola rosea

Abstract

<i>Rhodiola rosea</i> is a medicinal plant used by the indigenous Inuit people of Nunavik and Nunatsiavut, Eastern Canada, as a mental and physical rejuvenating agent. This traditional use led to the present investigation of <i>R. rosea</i> in the context of anxiety disorders. An alcohol extract of <i>R. rosea</i> roots was characterized phytochemically and orally administered for three consecutive days to Sprague-Dawley rats at 8 mg/kg, 25 mg/kg, and 75 mg/kg body weight. The rats were subjected to three behavioral paradigms of anxiety, including the elevated plus maze, social interaction, and contextual conditioned emotional response tests. <i>Rhodiola rosea</i> showed dose-dependent anxiolytic activity in the elevated plus maze and conditioned emotional response tests, with moderate effects in the higher-anxiety SI test. The active dose varied according to the anxiety test. In order to elucidate a mechanism, the extract was further tested in an <i>in vitro</i> GABA_A-benzodiazepine receptor-binding assay, where it demonstrated low activity. This study provides the first comparative assessment of the anxiolytic activity of Nunavik <i>R. rosea</i> in several behaviour models and suggests that anxiolytic effects may be primarily mediated via pathways other than the GABA_A-benzodiazepine site of the GABA_A receptor.