Determination of Histamine in Microdialysis Samples from the Rodent Brain by Column Liquid Chromatography

Microdialysis sampling in combination with a suitable analytical method enables in vivo monitoring of histamine release and metabolism in selected brain structures of experimental animals including rats and mice. In the alkaline medium, histamine reacts with o -phthalaldehyde (OPA) to form fluorescence products. This feature has been utilized for sensitive determination of histamine by HPLC with postcolumn OPA derivatization of histamine in the microdialysates and other biological samples. Even higher sensitivity and specificity could be achieved by precolumn derivatization of histamine with two molecules of a highly fluorescent tag such as 4-(1-pyrene)butyric acid N -hydroxysuccinimide ester (PSE), which yields the formation of the fluorescence intramolecular excimer. This chapter provides a detailed description of these two principal derivatization methods used for HPLC determination of histamine in the microdialysis samples and a summary of the most typical applications of monitoring histamine release in experimental neuropharmacology, neuroendocrinology and neurophysiology.