Nyctinastic herbs decoction improves para-chlorophenylalanine-induced insomnia by regulating the expression level of neurotransmitters

BACKGROUND: As traditional Chinese medicine (TCM), nyctinastic herbs have been used in treating insomnia in China since ancient times according to its similar circadian rhythm as human beings. However, the pharmacodynamic characteristics and mechanism of these herbs have not been explored in depth. METHODS: In the study, we chose He Huan Pi (Albizia julibrissin Durazz.), Ye Jiao Teng (Polygonum multiflorum Thunb.), Bai He (Lilium brownie F. E. Brown var. viridulum Baker), and Lianzi (Nelumbo nucifera Gaertn) to form a TCM compound decoction [nyctinastic herb decoction (NHD)] and to investigate its sedative and hypnotic effect on para-chlorophenylalanine (PCPA)-induced insomnia rodents by pentobarbital-induced sleep test (PIST), behavior test [including locomotor activity (LMA), forced swim test (FST), tail suspension test (TST)] and electroencephalograph (EEG). The expression of neurotransmitters were detected to explain the possible mechanism of NHD. RESULTS: NHD was found to have good sedative effects on reducing the moving distance, prolonging sleep time, improving the sleep quality and depression status. NHD attenuated the insomniac effect of PCPA by increasing the level of 5-hydroxytryptamine (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA), and reducing the level of dopamine (DA), norepinephrine (NE), acetylcholine (ACh) in the hypothalamus. CONCLUSIONS: The findings of the present study confirmed the sedative and hypnotic effect of NHD, and clarified its possible mechanism from neurotransmitters.