Dopamine-β-Hydroxylase (DBH), Its Cofactors and Other Biochemical Parameters in the Serum of Neurological Patients in Bangladesh

Dopamine-β-hydroxylase (DBH) is a neurotransmitter synthesizing enzyme which catalyzes the formation of norepinephrine from dopamine. In this study, we measured the level of DBH activity in the serum of patients of three different age groups (8-14 yrs, 20-40 yrs and 45-60 yrs) suffering from neurological diseases. Serum DBH activity was measured in 38 neurological patients and 38 normal individuals in order to determine significant variables for its potential use to diagnose the neurological patients. It was found that the DBH activity decreased in the patients of all age groups. A considerable decrease in activity was observed in the patients of 8-14 yrs age group (14.2 nmoles/min/ml in patients compared to the normal value of 22.6). A significant decrease in activity was found in the 20-40 yrs age group (23.4 nmoles/min/ml in patients compared to the normal value of 33.0). The decrease in DBH activity was also found in the patients of 45-60 yrs age group but to a lesser extent (26.4 nmoles/min/ml in the patients compared to the normal value of 30.2). The kinetic studies of DBH exhibited an increase of Km value and a decrease in Vmax in the neurological patients. Serum copper and ascorbic acid levels (cofactors of DBH) were found to be decreased in neurological patients and hence are in agreement with the decrease in DBH activity in these patients. Other parameters such as glucose and cholesterol levels increased, protein and zinc levels decreased and ALT, AST, creatinine and urea content remained nearly unchanged in the patients' serum.