Cisterna Magna Injection in Rats to Study Glymphatic Function

The recently discovered glymphatic system, which supports brain-wide clearance of metabolic waste, has become the subject of intense research within the past few years. Its nomenclature arose due to its functionally analogous nature to the lymphatic system in combination with glial cells that are part of its anatomical boundaries. The influx of cerebrospinal fluid (CSF) from perivascular spaces into the brain interstitium acts to clear intraparenchymal solutes. CSF is produced by the choroid plexus and flows from the ventricles to the subarachnoid space via the cisterna magna, and as such the injection of tracer molecules into any one of these spaces could be used for studying CSF movement through the glymphatic system. Of these options, the cisterna magna is most favorable as it offers a route of entry that does not involve craniotomy. Herein we describe the cisterna magna (CM) injection procedure carried out in rats, essential for studying glymphatic influx and efflux dynamics.