Rationale: Dopamine beta-hydroxylase (DBH) converts dopamine (DA) to norepinephrine (NE), thus playing a critical role in catecholamine metabolism.
Objectives/methods: We examined the effects of Dbh gene dosage and the DBH inhibitor disulfiram in mice with zero, one, or two null Dbh alleles (+/+, +/-, and-/- mice).
Results: DBH protein levels in adrenal and prefrontal cortex (PFC) and adrenal DBH activity were proportional to number of wild-type alleles. Adrenal DA was slightly increased in+/- mice and markedly increased (80-fold) in -/- mice compared to wild-type animals. While adrenal NE and epinephrine (EPI) were undetectable in -/- mice, adrenal concentrations of NE and EPI were similar in +/+ and +/- mice, suggesting that the increase in DA maintains the normal rate of beta-hydroxylation in Dbh +/- mice. Disulfiram had little effect on adrenal catecholamine levels, regardless of genotype or dose. NE was absent in the PFC of -/- mice, but only slightly reduced in +/- animals compared to wild-type animals. PFC DA was increased twofold in +/- mice and fivefold in -/- mice, and the NE to DA ratio was reduced ( approximately 35%) in +/- mice, compared to wild-type mice. Disulfiram significantly decreased PFC NE and increased DA in +/+ and +/- animals, with the disulfiram and genotype effects on the PFC NE to DA ratio apparently additive.
Conclusions: The data reveal potentially important and apparently additive effects of Dbh genotype and disulfiram administration on PFC catecholamine metabolism. These effects may have implications for genetic control of DBH activity in humans and for understanding therapeutic effects of disulfiram.