Self-stimulation and noradrenaline: evidence that inhibition of synthesis abolishes responding only if the "reserve" pool is dispersed first.

Although noradrenaline (NA) is thought to play a critical role in electrical self-stimulation, suppression of NA synthesis by injection of the dopamine-beta-hydroxylase inhibitor, FLA-63 (Hässle) (25 mg/kg), had little or no effect on response rates. But 3 or 5 days after prior reserpinisation, FLA-63 in the same dosage suppressed or profoundly depressed self-stimulation without eliciting signs of general incapacity. Suppression of self-stimulation could be reversed by intraventricular injection of NA, indicating that the depressant effect depended specifically on NA depletion. These findings support the view that NA may play a necessary role in self-stimulation and indicate that the NA available for this purpose included intraneuronal NA in a reserpine-sensitive reserve pool.