Hydroalcoholic extract of needles of Pinus eldarica enhances pentobarbital-induced sleep: possible involvement of GABAergic system

OBJECTIVE: Insomnia is accompanied by several health complications and the currently used soporific drugs can induce several side effects such as psychomotor impairment, amnesia, and tolerance. The present study was planned to investigate the sleep prolonging effect of Pinus eldarica. MATERIALS AND METHODS: Hydroalcoholic extract (HAE) of P. eldarica, its water fraction (WF), ethyl acetate fraction (EAF) and n-butanol fraction (NBF) were injected (intraperitoneally) to mice 30 min before administration of pentobarbital. Then, the latent period and continuous sleeping time were recorded. Also, LD(50) of P. eldarica extract was determined and the possible neurotoxicity of the extract was tested on neural PC12 cells. RESULTS: The HAE and NBF decreased the latency of sleep (p<0.05) and significantly increased duration of sleep (p<0.05) induced by pentobarbital. These effects of P. eldarica were reversed by flumazenil. The LD(50 )value for HAE was found to be 4.8 g/Kg. HAE and its fractions did not show neurotoxic effects in cultured PC12-cell line. CONCLUSION: The present data indicate that P. eldarica potentiated pentobarbital hypnosis without major toxic effect. Most probably, the main components responsible for this effect are non-polar agents which are found in NBF of this plant.