Chemical Composition and Hypnotic Effect of Picea mariana Essential Oils

Abstract

With rapid economic development, social competition has become increasingly intense. Stress experienced by individuals has increased dramatically, resulting in a steady rise in insomnia. The present study investigated the effect of different concentrations of Picea mariana essential oils (PMEOs) on sleep improvement in mice exhibiting p-chlorophenylalanine (PCPA)-induced insomnia. First, the main constituents of PMEOs were analyzed by gas chromatography-mass spectrometry (GC-MS). The mice were weighed daily, and the sleep latency and duration were measured in each mouse group in the inverted reflex experiment. The number of neurons in the mouse brain was measured using Nissl staining. The expression level of 5-hydroxytryptamine-1A (5-HT1A) was determined by immunohistochemistry, whereas the expression level of gamma-aminobutyric acid A receptor subunit alpha-1 (GABAARɑ1) was detected by immunohistochemistry, western blotting, and reverse transcription-quantitative PCR (RT-qPCR). GC-MS identified the top five components comprising PMEOs as bornyl acetate, camphene, α-pinene, β-pinene, and 3-carene. Inhalation of PMEOs resulted in a progressive increase in the rate of body weight change, a decrease in sleep latency, and prolonged sleep duration in experimental mice. In Nissl staining, the number of neurons was significantly reduced in the PCPA group when compared with the elevated number in the PMEOs group. Immunohistochemistry revealed increased expression levels of GABAARα1 and 5-HT1A in the PMEOs group. Western blotting and RT-qPCR results showed increased levels of GABAARα1 protein and gene expression, respectively. PMEOs could increase GABAARα1 and 5-HT1A protein levels in mice, resulting in hypnotic effects.