41 Journal of Chromatography, 433 (1988) 41-51 BLomedical zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA Apphatlons Elsevier Science Publishers B.V., Amsterdam - Printed in The Netherlands CHROMBIO. 4392 SENSITIVE METHOD FOR DETERMINATION OF PICOGRAM AMOUNTS OF EPINEPHRINE AND OTHER CATECHOLAMINES IN MICRODISSECTED SAMPLES OF RAT BRAIN USING LIQUID CHROMATOGRAPHY WITH ELECTROCHEMICAL DETECTION J. OPACKA-JUFFRY*, F. TACCONELLI and C W COEN Department of Anatomy and Human Biology, Ktng’s College London, Strand, London WC2R 2LS (UK) (First received May 6th, 1988; revised manuscript received July 7th, 1988) SUMMARY Liquid chromatography with high-sensitivity electrochemical detection has been employed to mea- sure picogram amounts of epinephrine and other catecholamines in microdissected samples of the rat hypothalamus. Tissue catecholamines are purified by solvent extraction; this provides better se- lectivity and recovery than methods involving alumina. The solvent extraction technique has been modified in order to eliminate its major disadvantage, the presence of electroactive substances sep- arating with catecholamines. Detection limits of zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON below 1 pg allow for analysis of catecholamines including epinephrine in very small brain samples such as micropunches INTRODUCTION Despite extensive research on the neurobiology of catecholamines, the role of epinephrine (E) in the mammalian central nervous system (CNS) remains ob- scure. The adrenergic innervation shown by immunohistochemical studies within the hypothalamus suggests an involvement of E in the regulation of food and water intake, sleep, body temperature and reproductive processes [l-3]. Since E is present in the brain at a relatively low concentration [with a ratio of E to norepinephrine (NE) of approximately zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPON 1: 50 in the rat], there are considerable problems concerning the specificity and sensitivity of the analytical methods used for its measurement. These problems are particularly important when attention is focused on “discrete” subregions of the brain, but they have received little attention apart from recent descriptions of E measurement using microbore high- performance liquid chromatography (HPLC) [4,5]. We have employed HPLC with coulometric detection because it has been shown 0378-4347/88/$03.50 0 1988 Elsevier Science Publishers B.V.