Sinomenium acutum has been long used in the preparations of traditional medicine in Japan, China and Korea for the treatment of various disorders including rheumatism, fever, pulmonary diseases and mood disorders. Recently, it was reported that Sinomenium acutum, has sedative and anxiolytic effects mediated by GABA-ergic systems. These experiments were performed to investigate whether sinomenine (SIN), an alkaloid derived from Sinomenium acutum enhances pentobarbital-induced sleep via γ-aminobutyric acid (GABA)-ergic systems, and modulates sleep architecture in mice. Oral administration of SIN (40 mg/kg) markedly reduced spontaneous locomotor activity, similar to diazepam (a benzodiazepine agonist) in mice. SIN shortened sleep latency, and increased total sleep time in a dose-dependent manner when co-administrated with pentobarbital (42 mg/kg, i.p.). SIN also increased the number of sleeping mice and total sleep time by concomitant administration with the sub-hypnotic dosage of pentobarbital (28 mg/kg, i.p.). SIN reduced the number of sleep-wake cycles, and increased total sleep time and non-rapid eye movement (NREM) sleep. In addition, SIN also increased chloride influx in the primary cultured hypothalamic neuronal cells. Furthermore, protein overexpression of glutamic acid decarboxylase (GAD65/67) and GABAA receptor subunits by western blot were found, being activated by SIN. In conclusion, SIN augments pentobarbital-induced sleeping behaviors through GABAA-ergic systems, and increased NREM sleep. It could be a candidate for the treatment of insomnia.

Angelicae Gigantis Radix (AGR, Angelica gigas) has been used for a long time as a traditional folk medicine in Korea and oriental countries. Decursinol angelate (DCA) is structurally isomeric decursin, one of the major components of AGR. This study was performed to confirm whether DCA augments pentobarbital-induced sleeping behaviors via the activation of GABAA-ergic systems in animals. Oral administration of DCA (10, 25 and 50 mg/kg) markedly suppressed spontaneous locomotor activity. DCA also prolonged sleeping time, and decreased the sleep latency by pentobarbital (42 mg/kg), in a dose-dependent manner, similar to muscimol, both at the hypnotic (42 mg/kg) and sub-hypnotic (28 mg/kg) dosages. Especially, DCA increased the number of sleeping animals in the sub-hypnotic dosage. DCA (50 mg/kg, p.o.) itself modulated sleep architectures; DCA reduced the counts of sleep/wake cycles. At the same time, DCA increased total sleep time, but not non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. In the molecular experiments. DCA (0.001, 0.01 and 0.1 µg/ml) increased intracellular Cl- influx level in hypothalamic primary cultured neuronal cells of rats. In addition, DCA increased the protein expression of glutamic acid decarboxylase (GAD65/67) and GABAA receptors subtypes. Taken together, these results suggest that DCA potentiates pentobarbital-induced sleeping behaviors through the activation of GABAA-ergic systems, and can be useful in the treatment of insomnia.

− Rhynchophylline (RP) is a major tetracyclic oxindole alkaloid of Uncariae Ramulus et Uncus which has been used to treat hypertension, seizures, pain and anxiety in the oriental countries. A recent report revealed that RP attenuated ischemia-induced neuronal damage and kainite-induced convulsions in animals. This study was performed to investigate whether RP enhances pentobarbital-induced sleep behaviors and modulates sleep architecture in mice. Locomotor activity was significantly inhibited by RP at 0.25 and 0.5 mg/kg, similar to 2 mg/ kg diazepam (a benzodiazepine agonist) in mice. RP shortened sleep latency and increased total sleep time in a dose-dependent manner when administrated with pentobarbital (42 mg/kg, i.p.). RP also increased the number of sleeping mice and total sleep time by concomitant administration with the sub-hypnotic dosage of pentobarbital (28 mg/kg, i.p.). On the other hand, RP (0.25 mg/kg, p.o.) itself significantly inhibited sleep-wake cycles, prolonged total sleep time, and rapid eye movement in rats. In addition, RP also increased chloride influx in the primary cultured hypothalamic neuronal cells. In addition, we found that glutamic acid decarboxylase (GAD 65/67 ) was activated by RP. In conclusion, RP augments pentobarbital-induced sleeping behaviors, and can be a candidate for treating insomnia.

− Perillae Herba has been traditionally used for the sedation in the oriental countries. Therefore, this study was conducted to determine whether Perillae Herba ethanol extract (PHEE) enhances pentobarbital-induced sleeping behaviors in animals. In addition, the possible mechanisms are demonstrated. PHEE (12.5, 25 and 50 mg/kg. p.o.) reduced the locomotor activity in mice. PHEE reduced sleep latency and augmented the total sleep time in pentobarbital (42 mg/kg, i.p.)-induced sleep in mice. Furthermore, the number of sleeping mice treated with sub-hypnotic pentobarbital (28 mg/kg, i.p.) increased. PHEE (50 mg/kg. p.o.) decreased the sleep/ wake cycles and wakefulness, and increased total sleeping time and NREM sleep in electroencephalogram (EEG) of rats. In addition, PHEE (0.1, 1.0 and 10 µg/ml) increased the intracellular Cl − level through the GABA receptors in the hypothalamus of rats. Moreover, the protein of glutamate decarboxylase (GAD) was overexpressed by PFEE. It was found that PHEE enhanced pentobarbital-induced sleeping behaviors through GABA A -ergic transmissions.