Long-term recording of cerebrospinal fluid pressure in freely behaving rats

Literature values for 'normal', 'control', 'resting' or 'baseline' cerebrospinal fluid pressure (CSF-p) of rats reveal a large variability. Anesthesia, restraint, brief recordings at variable times from various sites and simultaneous infusions into the recording cannula may partly explain the variability. Here, we report values of continuous, day/night CSF-p recordings from a lateral ventricle in conscious, relatively unrestrained and freely behaving rats. The mean (+/- S.E.M.) daytime/nighttime values were 11.4 +/- 2.0 and 14.9 +/- 2.3 cm H2O, respectively (P less than 0.05). Minimum, but not maximum CSF-p's during the day were lower (P less than 0.05) than at night. The results provide a normative data base for studies designed to evaluate experimental or pathological phenomena affecting CSF-p.