Neuronal MCT2 promotes angiogenesis via lactate in the developing mouse neocortex.

Neural activity drives blood vessel (BV) formation and energy substrate delivery in the developing brain to meet rising metabolic demands; however, the underlying mechanisms remain poorly understood. In this study, we exposed neonatal mice to chronic whisker stimulation (WS), a paradigm known to enhance BV formation in the somatosensory (S1) cortex. Transcriptomic (RNA-seq) and spatial (RNA-scope) analyses revealed that WS upregulated monocarboxylate transporter 2 (MCT2) in cortical neurons and MCT1 in endothelial cells (ECs). These changes coincided with increased cortical lactate levels, elevated astrocytic vascular endothelial growth factor A (VEGFa), and enhanced angiogenesis. Functional experiments demonstrated that neuronal MCT2 is essential for mediating WS-induced angiogenic and metabolic responses. Mechanistically, MCT2 facilitates _L-lactate influx into the cortex with or without WS, promoting lactate uptake by neurons and astrocytes. This, in turn, induces MCT2 expression in neurons and activates hypoxia-inducible factor 1α (HIF1α) and VEGFa expression in astrocytes. Together, these findings uncover a previously unrecognized role for neuronal MCT2 in regulating lactate flux, signaling, and vascular remodeling, thereby linking neural activity to metabolic adaptation and vascular development in the neonatal mouse neocortex.