Hypnotic activities of Zao Ren An Shen capsule, a traditional Chinese medicine, in an anxiety-like mouse model

Purpose Zao Ren An Shen capsule (ZRASC) which is composed of three kinds of traditional Chinese herbs is a popular Chinese medicine for the treatment of insomnia. This study investigated the hypnotic effect of ZRASC in an anxiety-like mouse model. Methods We determined the role of ZRASC in anxiety and co-morbid insomnia using electroencephalogram and electromyogram recordings. Anxiety-like behaviors were tested by using the open-field, light/dark box, or elevated plus-maze in mice. Immunohistochemical techniques were employed to reveal the mechanism by which ZRASC regulated anxiety and insomnia. Results ZRASC at 680 mg/kg prolonged the time spent in the central area, open arms area, and light box by 1.9, 2.3, and 1.7-fold respectively, compared with the vehicle control group in immobilization stress (IMS) mice. ZRASC at 680 mg/kg given at 08:00 h increased the amount of non-rapid eye movement sleep by 1.4-fold in a 2-h period after dosing in IMS mice. However, it did not alter the sleep-wake behaviors in normal mice. Immunohistochemistry showed that IMS increased c-Fos expression in the neurons of the stria terminalis and tuberomammillary nucleus by 1.8 and 1.6-fold, respectively. In addition, ZRASC (680 mg/kg) reversed the IMS-induced c-Fos expression. Conclusions Our results suggest that ZRASC is an effective therapeutic strategy for both anxiety disorder and sleep disturbances in an anxiety-like mouse model.