The basal forebrain-DMN/solv cholinergic projection mediates the attenuation of brain injury after cardiopulmonary resuscitation

BACKGROUND: To investigate the mechanism underlying the basal forebrain-DMN/solv cholinergic projection-induced attenuation of brain injury after cardiopulmonary resuscitation (CPR).METHODS: Forty-six male Sprague-Dawley rats were randomly divided into five groups: the sham group (n=6), the return of spontaneous circulation (ROSC) group (n=10), the optogenetic activation (CHAT-Light-CHR2) group (n=10), the optogenetic inhibition (CHAT-Light-NpHR) group (n=10), and the optogenetic activation combined with left cervical vagotomy (CHAT-Light-CHR2 + LcVGX) group (n=10).Excitatory (CHR2) or inhibitory (NpHR) optogenetic viruses were injected into the basal forebrain (BF) of rats, followed by the implantation of ceramic ferrules.After 3 weeks of viral expression, the sham group received tracheotomy and catheterization only, the ROSC group underwent tracheotomy, asphyxial cardiac arrest, and CPR, and the CHR2 and NpHR groups received post-ROSC optogenetic activation or inhibition, respectively.The CHAT-Light-CHR2 + LcVGX group was pretreated with left cervical vagotomy followed by post-ROSC activation.Post-ROSC assessments included neurofunctional deficit score (NDS), histopathology (HE/Nissl/TUNEL staining and CD11b microglial activation) in the hippocampal CA1/prefrontal cortex, serum cytokines (IL-1β, IL-6 and TNF-α), and whole-brain immunofluorescence (c-Fos/CHAT) for neuronal activation mapping. RESULTS:Compared with the rats of sham group, rats of the ROSC group presented reduced NDS, neuronal loss, increased apoptosis, elevated CD11b expression, and increased cytokine levels.CHAT-CHR2 activation improved NDS, reduced neuronal loss and apoptosis, and decreased CD11b expression and TNF-α levels.CHAT-NpHR inhibition caused no improvement in NDS but exacerbated neuronal loss and CD11b expression elevation.CHAT-CHR2+LcVGX reversed these protective effects.Whole-brain immunofluorescence staining revealed that optogenetic activation of cholinergic neurons in the BF of the CHAT-Light-CHR2 group excited neurons in the DMN/solv region, which were identified as dopaminergic neurons.CONCLUSION: Cholinergic projections from the basal forebrain-DMN/solv may alleviate systemic and neuroinflammatory responses through the cholinergic anti-inflammatory pathway and mitigate brain injury following CPR.