Objective
This study investigates the sleep-modulating effects of ginsenoside Rg1 (Rg1, C42H72O14), a key bioactive component of ginseng, and elucidates its underlying mechanisms.
Methods
C57BL/6J mice were intraperitoneally administered doses of Rg1 ranging from 12.5 to 100 mg/kg. Sleep parameters were assessed to determine the average duration of each sleep stage by monitoring the electrical activity of the brain and muscles. Further, orexin neurons in the lateral hypothalamus (LH) and corticotropin-releasing hormone (CRH) neurons in the paraventricular hypothalamic nucleus (PVH) were ablated using viral vector surgery and electrode embedding. The excitability of LHorexin and PVHCRH neurons was evaluated through the measurement of cellular Finkel-Biskis-Jinkins murine osteosarcoma viral oncogene homolog (c-Fos) expression.
Results
Rg1 (12.5–100 mg/kg) augmented the duration of non-rapid eye movement (NREM) sleep phases, while reducing the duration of wakefulness, in a dose dependent manner. The reduced latency from wakefulness to NREM sleep indicates an accelerated sleep initiation time. We found that these sleep-promoting effects were weakened in the LHorexin and PVHCRH neuron ablation groups, and disappeared in the orexin and CRH double-ablation group. Decreased c-Fos protein expression in the LH and PVH confirmed that Rg1 promoted NREM sleep by inhibiting orexin and CRH neurons.
Conclusion
Rg1 increases the duration of NREM sleep, underscoring the essential roles of LHorexin and PVHCRH neurons in facilitating the sleep-promoting effects of Rg1.

Key words: Insomnia, Lateral hypothalamus, Paraventricular hypothalamic nucleus, Ginsenoside Rg1, Non-rapid eye movement