Simultaneous determination of homovanillic acid, 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid in brain tissue, using a double-column procedure.

A double-column procedure for simultaneous determination of homovanillic acid (HVA), 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) in brain tissue was described. These compounds extracted with perchloric acid were adsorbed on Sephadex G-10 in the column. HVA and DOPAC were desorbed from Sephadex G-10 with 0.01 N HCl and then retained on QAE-Sephadex A-25 (acetate form) placed beneath the Sephadex G-10 column. HVA and DOPAC were eluted with small volume of 0.2 mol/l NaCl. 5-HIAA remaining on the Sephadex G-10 was eluted with 0.05 mol/l phosphate buffer at pH 7.5. Each substance was determined fluorometrically. The recovery rates of HVA, DOPAC and 5-HIAA were more than 80, 80 and 85%, respectively. Effects of oxypertine on dopamine (DA) neurons in the rat brain were investigated using the method described here. Oxypertine caused marked increases in the levels of HVA and DOPAC in cortex and striatum of the rat brain, without any obvious change in the level of 5-HIAA after the intraperitoneal administration of 10 mg/kg oxypertine. These findings suggest that the favorable antipsychotic action of oxypertine may be due not only to a marked reduction in brain norepinephrine level, but to a blockade of DA receptors.