Extract of Ganoderma lucidum prolongs sleep time in rats

Ganoderma lucidum (Ling Zhi) is a basidiomycete white-rot macrofungus that has been used as a tranquilizing agent (i.e., An-Shen effect) for the treatment of restlessness, insomnia, and palpitation in China for hundreds of years.The present study aimed to investigate whether Ganoderma lucidum extract (GLE) influences the sleep of freely moving rats and the potential mechanism.Ganoderma lucidum extract was extracted from fruiting bodies of Ganoderma lucidum. Rats were treated with GLE orally for 3 days, and on the third day, electroencephalographic and electromyographic recordings were made for 6h from 9:00 p.m. to 3:00 a.m. in freely moving rats. Sleep parameters were analyzed using SleepSign software. Tumor necrosis factor-α (TNF-α) levels were measured using the enzyme-linked immunosorbent assay.Three-day administration of GLE significantly increased total sleep time and non-rapid eye movement (NREM) sleep time at a dose of 80 mg/kg (i.g.) without influencing slow-wave sleep or REM sleep in freely moving rats. TNF-α levels were significantly increased concomitantly in serum, the hypothalamus, and dorsal raphe nucleus. The hypnotic effect of GLE (80 mg/kg, i.g.) was significantly inhibited by intracerebroventricular injection of TNF-α antibody (2.5 μg/rat). Co-administration of GLE (40 mg/kg, i.g.) and TNF-α (12.5 ng/rat, i.c.v.), both at ineffective doses, revealed an additive hypnotic effect.These results suggest that GLE has hypnotic effects in freely moving rats. The mechanism by which the extract promoted sleep remains unclear, but this effect appears to be primarily related to the modulation of cytokines such as TNF-α. Furthermore, these data at least partially support the ethnomedical use of Ganoderma lucidum.