Determination of brain 5-hydroxytryptamine turnover in freely moving rats using repeated sampling of cerebrovascular fluid.
A simple technique is described for repeated sampling of cerebrospinal fluid (CSF) from the freely moving rat and its use in the determinations of 5-hydroxytryptamine (5-HT) turnover validated. A catheter, constructed from polyethylene tubing (PP10) was implanted via a cranial approach into the cisterna magna and x-ray studies confirmed that the catheter avoided the cerebellum. 5-HT turnover was determined from the rate of rise of 5-hydroxyindoleacetic acid (5-HIAA) in both CSF and brain following an injection of probenecid (200 mg/kg i.p.). Concentrations of 5-HIAA, 5-HT and tryptophan were determined by high pressure liquid chromatography. Turnover values for individual rats were obtained using CSF samples. After p-chlorophenylalanine treatment (when brain 5-HT was depleted by 43%) 5-HT turnover values obtained were comparably reduced whether determined from CSF (-67%) or brain (-74%). Thus differences of rat brain 5-HT turnover are proportionately reflected by CSF measurements. The method for sampling of CSF should be applicable in a wide range of pharmacological and physiological situations.
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D010134:Fenclonine / Q000494:pharmacology; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D007700:Kinetics; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000134:cerebrospinal fluid / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D010134:Fenclonine