ABSTRACT
Many medicinal plants have been used in Asia for treating a variety of mental diseases, including insomnia and depression. However, their sedative-hypnotic effects and mechanisms have not been clarified yet. Accordingly, the objective of this study was to investigate the sedative-hypnotic effects of water extracts of five medicinal plants: Coptidis Rhizoma, Lycii Fructus, Angelicae sinensis Radix, Bupleuri Radix, and Polygonum multiflorum Thunberg. The binding abilities of five medicinal plant extracts to the GABAA-BZD and 5-HT2C receptors were compared. Their abilities to activate arylalkylamine N-acetyltransferase (AANAT), a melatonin synthesis enzyme, in pineal cells were also determined. Following in vitro tests, the sedative and hypnotic activities of extracts with the highest activities were determined in an animal sleep model. In the binding assay, the water extracts of Coptidis Rhizoma (WCR) showed high binding affinity to the GABAA-BZD and 5-HT2C receptors in a dose-dependent manner. Additionally, WCR increased the AANAT activity up to five times compared with the baseline level. Further animal sleep model experiments showed that WCR potentiated pentobarbital-induced sleep by prolonging the sleep time. It also decreased the sleep onset time in mice. In addition, WCR reduced wake time and increased non-rapid eye movement (NREM) sleep without EEG power density (percentages of δ, θ, and α waves) during NREM sleep in rats. WCR could effectively induce NREM sleep without altering the architectural physiologic profile of sleep. This is the first report of the sedative-hypnotic effect of Coptidis Rhizoma possibly by regulating GABAA and 5-HT2C receptors and by activating AANAT activity.
ABSTRACT
Grounding is a therapeutic technique that involves doing activities that "ground" or electrically reconnect us to the earth. The physiological effects of grounding have been reported from a variety of perspectives such as sleep or pain. However, its anti-stress efficacy is relatively unknown. The present study investigated the stress-related behavioral effects of earthing mat and its neurohormonal mechanisms in the Sprague−Dawley male rat. Rats were randomly divided into four groups: the naïve normal (Normal), the 21 days immobilization stressed (Control), the 21 days stressed + earthing mat for 7 days (A7) or 21 days (A21) group. The depressive-and anxiety like behaviors were measured by forced swimming test (FST), tail suspension test (TST) and elevated plus maze (EPM). Using immunohistochemistry, the expression of corticotrophin-releasing factor (CRF) and c-Fos immunoreactivity were analyzed in the brain. In the EPM, time spent in the open arm of the earthing mat groups was significantly increased compared to the Control group (p < 0.001), even though there were without effects among groups in the FST and TST. The expression of CRF immunoreactive neurons in the earthing mat group was markedly decreased compared to the Control group. Overall, the earthing mat reduced stress-induced behavioral changes and expression of c-Fos and CRF immunoreactivity in the brain. These results suggest that the earthing mat may have the potential to improve stress-related responses via the regulation of the corticotrophinergic system.
