Abstract
l-3, 4-Dihydroxyphenylalanine (l-dopa) causes a partial and temporary reversal of reserpine-induced suppression of a conditioned avoidance response (CAR). Disulfiram, a dopamine-β -hydroxylase inhibitor, reduced this effect of l-dopa by 50%. It was found that both dopamine (DA) and norepinephrine (NE) levels in brain increased as a result of the l-dopa injection (400 mg/kg) in mice pretreated with reserpine (2.5 mg/kg), although the relative increase in DA greatly exceeded that of NE. While DA levels increased to six to seven times normal, NE levels increased to only about 13% of normal. This small rise in NE was blocked by disulflram (400 mg/kg), and the behavioral effect noted suggests that this small increment is of functional importance. These results suggest that both DA and NE play a role in the maintenance of the CAR.
Footnotes
- Received December 7, 1967.
- Accepted April 26, 1968.
- © 1968, by The Williams & Wilkins Company
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