The copper levels in the plasma and dopamine beta-hydroxylase activity in a chronic mild stress model of depression in rats

Dopamine beta-hydroxylase (DBH) catalyzes the beta-hydroxylation of dopamine into norepinephrine. Its decreased activity has been reported in unipolar psychotic depression. DBH is known to use copper ions for catalytic activity. Our objective was to study the effect of chronic mild stress (CMS) in the rat model of depression on the content of copper in the plasma and the DBH activity. DBH was isolated from blood plasma. It's activity was measured by the Nagatsu and Udenfriend method, modified by Grabowska and Guminska, based on the oxidation of tyramine to octopamine. The octopamine was oxidized to p-hydroxybenzaldehyde. The absorbance of the second was measured spectrophotometrically at 330 nm. The copper content in the plasma was measured by AAS method. The copper content in the plasma in the chronic mild stress of the rat's depression model remains stable.(0.87-1.11 mg/l), whereas the DBH activity is altered (22.84-73.14 umol/min/l). There exists a negative significant correlation between the content of copper in the plasma and the activity of DBH in the rats subjected to CMS (r=-0.48, p<0.05).