Role of gamma-aminobutyric acid-ergic neurons in the thalamic reticular nucleus in regulating sleep-wake cycles in mice treated with acupuncture for insomnia.

OBJECTIVE

To test whether acupuncture improves sleep by enhancing gamma-aminobutyric acid-ergic (GABA) neuronal activity in the thalamic reticular nucleus (TRN).

METHODS

We established an animal model using p-chlorophenylalanine (PCPA). We assessed the impact of acupuncture on insomnia through wheel-running activity and sodium pentobarbital-induced sleep tests. Subsequently, the calcium indicator GCaMP6m was injected into the TRN of Vgat-Cre mice, and the activity of GABA neurons in the TRN was analyzed before and after acupuncture using fiber photometry recording. Additionally, cortical electroencephalography (EEG) recordings were compared between groups following chemogenetic inhibition of GABA neurons in the TRN.

RESULTS

Following acupuncture, we observed a reduction in sleep latency and an increase in sleep duration in comparison to the PCPA-induced insomnia (P < 0.01). Furthermore, acupuncture positively influenced the diurnal phase of insomnia (P < 0.01). Ca2+ signals in GABA neurons within the TRN increased post-acupuncture (paired t-test, P< 0.01). Acupuncture also reduced the proportion of EEG power in the elevated Beta and Gamma frequencies associated with PCPA injection, while simultaneously increasing the Delta power ratio (P < 0.01). Chemogenetic inhibition of TRN GABA neurons blocked these acupuncture effects: the hM4Di + MA group showed no significant differences from the PCPA group in Beta and Gamma power, but exhibited elevated Beta and Theta activity compared to controls (P < 0.05).

CONCLUSIONS

Acupuncture activates GABA neurons in the TRN, thereby regulating the sleep-wake cycle in the context of PCPA-induced insomnia.