Cocaine-induced structural and functional impairments of the glymphatic pathway in mice

The glymphatic system plays a central role in the clearance of extracellular wastes from the brain. Cocaine exposure can lead to pathologies that affect the entire brain, resulting in addictive disorders involving motivational and cognitive impairment. However, it remains unknown whether cocaine exposure impairs glymphatic function. In the present study, using a mouse model of noncontingent cocaine exposure, we evaluated glymphatic function including cerebrospinal fluid (CSF)-interstitial fluid (ISF) exchange and solute clearance during repeated exposures and withdrawal. We found that cocaine treatment, both during repeated exposure and withdrawal, significantly induced widespread astrogliosis and reduced cerebral blood flow (CBF), cerebrovascular pulsatility, and aquaporin-4 (AQP4) polarity. Glymphatic function was greatly impaired in mice after cocaine treatment, as evidenced by reduced CSF influx from paravascular pathways into the brain parenchyma and decreased efflux of interstitial molecules out of the parenchyma. These findings provide evidence that cocaine exposure impairs the clearance of wastes from the brain, which may contribute to the development of neurocognitive disorders in patients with drug addictions.