Cocaine induced astrocytic activation was associated with its vasoconstricting effects independent of its neuronal...

Astrocytes bridge neuronal and cerebrovascular systems, regulating neurotransmitter dynamics and modulating neurovascular coupling (NVC). Cocaine disrupts neuronal, astrocytic, and cerebrovascular system function, which in the prefrontal cortex (PFC), could interfere with executive function. Though astrocytes are known to influence neurotoxic and addictive effects of cocaine through their regulations of local neurotransmitter environments, their role in cocaine-induced vasoconstriction and dysregulated NVC remains unclear. To investigate astrocytic regulation of vascular response to cocaine, we expressed the genetically encoded calcium indicator GCaMP6f in either neurons or astrocytes alongside concurrent expression of astrocytic DREADD(Gq) in the mouse PFC. Hemodynamic changes and cellular Ca2+ responses to an acute cocaine challenge (1 mg/kg, i.v.) with and without DREADD(Gq) activation were recorded through a cranial window using a custom multi-wavelength imaging platform. We found that when naïve animals were exposed to acute cocaine, intracellular Ca2+ increased in both astrocytes (Ca2+A) and neurons (Ca2+N), cerebral blood vessels vasoconstricted, and oxygenated hemoglobin in tissue (HbO2) decreased. Activation of astrocytes by DREADD(Gq) exposure also caused long-lasting increases in Ca2+A and vasoconstriction. Consequently, when cocaine was administered after astrocytic activation, there was further Ca2+A elevation and vasoconstriction but limited in magnitude, suggesting a ceiling effect. Meanwhile, cocaine induced increases in Ca2+N were unaffected. Correlation analysis revealed a strong negative association between Ca2+A and cerebrovascular diameters, while Ca2+N was negatively correlated with HbO2 and this correlation remained unchanged by astrocytic activation. These findings support astrocytes’ involvement in regulating vascular tone including cocaine’s vasoconstricting effects and its disruption of neurovascular coupling. Astrocytes present a potential therapeutic target to alleviate cerebrovascular pathology triggered by cocaine that merits further investigation.