Chemogenetic Activation of Neurons Promotes Axonal Regeneration and Ameliorates Neurological Deficits in Mice with...

Intracerebral hemorrhage (ICH) is a devastating neurological condition characterized by high morbidity and mortality, with limited treatment options for promoting neurological recovery. Enhancing cortical excitability has emerged as a potential strategy for promoting neurological recovery. However, the role of neuronal activation in mitochondrial regulation and axonal regeneration after ICH remains unclear. A chemogenetic approach using adeno-associated virus (AAV)-human M3 muscarinic designer receptor exclusively activated by designer drugs (hM3Dq) was employed to selectively activate cortical excitatory neurons in an ICH mouse model. Behavioral assessments, histological analyses, and molecular evaluations of mitochondrial function and axonal integrity were performed. In vitro, PC12 cells were transfected with hM3Dq and subjected to Hemin-induced injury to assess mitochondrial dynamics and neurite outgrowth. Dynamin-related protein 1 (DRP1) overexpression was used to investigate the role of mitochondrial fission in hM3Dq-mediated effects. hM3Dq activation significantly improved motor and cognitive functions in ICH mice, reduced neuronal apoptosis, and enhanced axonal regeneration. These effects were associated with restored mitochondrial membrane potential, reduced oxidative stress, increased adenosine triphosphate (ATP) production, and partially restored mitochondrial dynamics-related protein expression. In vitro, hM3Dq overexpression mitigated mitochondrial dysfunction and promoted neurite elongation in PC12 cells. Importantly, DRP1 overexpression reversed these beneficial effects, suggesting that inhibition of mitochondrial fission is critical for hM3Dq-mediated neuroprotection. Chemogenetic activation of cortical neurons promotes neurological recovery after ICH and is associated with improved mitochondrial function and enhanced axonal regeneration. Modulation of DRP1-related mitochondrial fission signaling may partially contribute to these effects, suggesting a potential neuron-mitochondria interaction that may serve as a therapeutic target for hemorrhagic stroke.