Pharmacology of electrically evoked dopamine release studied in the rat olfactory tubercle by in vivo electrochemistry

Abstract

Dopamine (DA) release was evoked by electrical stimulation of the dopaminergic pathway. Electrically evoked DA release was monitored in the olfactory tubercle of anesthetized rats using differential pulse amperometry (DPA) combined with a treated carbon fiber electrode. Systemic injection of α-methyl-para-tyrosine (AMPT 250 mg/kg), NSD-1015 (50 mg/kg), reserpine (5 mg/kg), d,l-apomorphine (400 μg/kg) decreased evoked DA release while pargyline (75 mg/kg), nomifensine (4 and 20 mg/kg), methylphenidate (10 mg/kg), amphetamine (0.5, 2 and 5 mg/kg), sulpiride (20 mg/kg) and haloperidol (50 μg/kg) enhanced it. Thus, evoked DA release as measured indirectly by DPA is dependent upon synthesis, catabolism and vesicular processes. It can be also affected by DA releasers, DA re-uptake inhibitors, DA agonists and DA antagonists. These results suggest that under our experimental conditions all the drugs tested act directly on DA nerve terminals to modulate in vivo the evoked DA release.