Continuous sampling of cerebrospinal fluid in the conscious rabbit

A cannulation technique for continuous sampling of cerebrospinal fluid (CSF) in unanesthetized freely moving rabbits is described. A permanent stainless steel cannula constructed easily and inexpensively from commercially available material is placed into the third ventricle and fixed to the skull by anchoring screws and dental cement. This procedure allows a continuous CSF sampling with a flow rate of 11.2 +/- 4.5 microliters/min without any sign of disturbing the animal. The penetration of the third ventricle or the periodic drainage of CSF, during a one month period, does not result in a variation of CSF protein (356 +/- 20 mg/l), glucose (4.5 +/- 0.2 mmol/l) or lactate (1.80 +/- 0.05 mmol/l) concentrations. Our technique has some advantages for pharmacological or pharmacokinetic investigations. The third ventricle CSF data will complete that of cisterna magna or lateral ventricle CSF. This method allows studies in the same animal during a period of one month without any problem. Moreover, it lends itself to experiments in which physiological conditions are required.