Time course analysis of para-chlorophenylalanine induced suppression of self-stimulation behavior

The hypothesis of a serotonergic basis of reward rests partly on data showing that serotonin (5-HT) depletion by para-chlorophenylalanine (p-CPA) causes depression of self-stimulation (SS) rates. These data do not clearly demonstrate a time course relationship between 5-HT depletion and SS suppression. The present study shows that SS behavior has fully recovered from p-CPA induced suppression when 5-HT levels are still maximally depleted. The data reveal that the effects of electrical brain SS on p-CPA induced reductions of 5-HT cannot explain the temporal dissociation between 5-HT depletion and SS suppression. As a whole the data suggest that midbrain 5-HT neurons are not critically involved in SS behavior.