A rapid and simple cannulation technique for repeated sampling of cerebrospinal fluid in freely moving rats

A cannulation technique for frequent sampling of cerebrospinal fluid (CSF) in unanaesthetized freely moving rats is described. A permanent stainless steel cannula, constructed in such a way that no loss of CSF occurs, is placed into the rat's cisterna magna and fixed to the skull by anchoring screws and dental cement. A special CSF outflow opening of the cannula is connected to polyethylene tubing for CSF sampling. Amounts of 50-150 microliters CSF can be collected repeatedly without any sign of disturbing the animal. The technique lends itself not only to pilot studies in which within a short period of time a large amount of CSF is wanted, but also to experiments in which physiological conditions are required.