Sedative, hypnotic and anticonvulsant activities of the ethanol fraction from Rhizoma Pinelliae Praeparatum

Ethnopharmacological relevance: Rhizoma Pinelliae Praeparatum is the product of raw Rhizoma Pinellia processed with alkaline solution and Licorice, which had been widely used for treatment of insomnia in traditional Chinese medicine. The present study aimed to investigate the sedative, hypnotic and anticonvulsant activities of ethanol fraction from Rhizoma Pinelliae Praeparatum (EFRP) and to determine whether these effects were related to GABAergic mechanism. Materials and methods: The sedative, hypnotic and anticonvulsant activities of EFRP were investigated with locomotion activity, pentobarbital-induced sleeping and nikethamide (NKTM)-induced convulsion tests, respectively. Additionally, the effects of flumazenil (an antagonist of GABA(A) receptor) and L-malic acid (blocker of synthetic enzyme for GABA) on the hypnotic activity of EFRP were evaluated. Results: EFRP at dose of 12 g/kg significantly inhibited the locomotion activity of mice. EFRP showed synergic effect on pentobarbital-induced sleeping by increased numbers of mice falling asleep, reduced the sleep latency and prolonged the sleeping time. L-malic acid and flumazenil inhibited the augment effects of EFRP on pentobarbital-induced sleeping. EFRP promoted a significant protection to NKTM-induced convulsion, by prolonged the death latency and decreased mortality. Conclusion: EFRP possessed sedative, hypnotic and anticonvulsant activities and these activities may be related to the GABAergic system. (C) 2011 Elsevier Ireland Ltd. All rights reserved.