Positive effects of β-amyrin on pentobarbital-induced sleep in mice via GABAergic neurotransmitter system

• Pentobarbital-induced sleeping behavior was prolonged by β-amyrin.
• Increased sleeping behavior was blocked by GABAA receptor antagonist.
• Brain GABA level was increased by β-amyrin administration.

Sleep loss, insomnia, is considered a sign of imbalance of physiological rhythm, which can be used as pre-clinic diagnosis of various neuropsychiatric disorders. The aim of the present study is to understand the pharmacological actions of α- or β-amyrin, natural triterpene compound, on the sleep in mice. To analyze the sleeping behavior, we used the well-known pentobarbital-induced sleeping model after single administration of either α- or β-amyrin. The sleeping onset time was remarkably decreased and duration was prolonged by β-amyrin (1, 3, or 10 mg/kg) but not by α-amyrin (1, 3, or 10 mg/kg). These effects were significantly blocked by GABAA receptor antagonist, bicuculline. Moreover, β-amyrin increased brain GABA level compared to the vehicle administration. Overall, the present study suggests that β-amyrin would enhance the total sleeping behavior in pentobarbital-induced sleeping model via the activation of GABAergic neurotransmitter system through GABA content in the brain.