Transcranial near-infrared stimulation alleviates stress-induced depressive-like behaviors by restoring prefrontal neurometabolic and synaptic pathways

Depression is associated with disrupted neural energy metabolism and synaptic dysfunction. Transcranial near-infrared (tNIR) stimulation is a promising non-invasive intervention, but optimal parameters and cellular mechanisms remain unclear. Here, we compared pulsed tNIR delivered at 10 Hz, 100 Hz, or 1000 Hz targeting the prefrontal cortex (PFC) in a chronic restraint stress (CRS) rat model and profiled PFC nuclei using single-nucleus RNA sequencing. Behavioral assays showed that 100 Hz tNIR, but not 10 Hz or 1000 Hz, robustly alleviated depressive-like and anxiety-like behaviors. Transcriptomic analyses further showed that CRS induced widespread dysregulation of mitochondrial and membrane-related gene networks, which were selectively normalized by 100 Hz tNIR. At the cell-type level, tNIR reversed stress-induced mitochondrial respiratory gene upregulation in both excitatory and inhibitory neurons, and restored pathways related to synaptic organization, neuronal excitability, and lipid/sterol homeostasis in excitatory neuron. Coordinated transcriptional reversals were also observed in glial populations. Consistently, 100 Hz tNIR increased activation of glutamatergic neurons in the medial PFC. Together, these results identify 100 Hz as an effective stimulation frequency and link its antidepressant effects to normalization of stress related neurometabolic pathways and enhanced glutamatergic activation in the PFC.