Extracts of Prunella vulgaris Enhanced Pentobarbital-Induced Sleeping Behavior in Mice Potentially via Adenosine A2A Receptor Activity.

The increasing prevalence of sleep dysregulation cases has prompted the search for effective and safe sleep-enhancing agents. Numerous medications used in the treatment of sleep disorders function by enhancing γ-aminobutyric acid neurotransmitter activity. Unfortunately, these substances may induce significant adverse effects in chronic users, such as dependence and motor behavior impairments. Consequently, there is a growing interest in exploring therapeutic sleep-enhancing agents derived from natural sources, with the anticipation of causing less severe side effects. Prunella vulgaris (PV), a perennial plant indigenous to South Korea, exhibits various pharmacological effects, likely attributed to its chemical composition. Rosmarinic acid, one of its components, has previously demonstrated sleep-potentiating properties, suggesting the potential for PV to exhibit similar pharmacological effects. This study aims to investigate the potential effects of repeated administration of PV extract on the sleep behavior, brainwave activity, sleep-wake cycle, and physiological behavior of mice. Findings indicate that PV extracts exhibit sleep-enhancing effects in mice, characterized by prolonged sleep duration and a reduced onset time of pentobarbital-induced sleep. However, PV extracts only reduced alpha wave powers, with minor alterations in wakefulness and rapid-eye-movement sleep duration. In contrast to diazepam, PV extracts lack adverse effects on locomotor activity, motor coordination, or anxiety in mice. Receptor-binding assay and caffeine treatment support the potential involvement of adenosine A_2A receptors in the effects of PV, suggesting distinct mechanisms of action compared to diazepam, despite both exhibiting sleep-altering effects. Overall, our results suggest that PV holds promise as a potential source of sleep-aiding agents.