| Abstract: | 1. The effects of serotonin depletion on the behaviors evoked by apomorphine or amphetamine are analyzed. Amphetamine (5 mg/kg, s.c.) or apomorphine (2 mg/kg, s.c.) were administered to fourteen adult mongrel cats. Inhibition of tryptophan hydroxylase was achieved by intraperitoneal injection of p-chlorophenylalanine (100 mg/kg daily for three consecutive days). Serotonin depleted animals were tested with either apomorphine or amphetamine (same doses as above). 2. Behaviors evoked by both drugs were recorded and quantified. The following behaviors were rated: motility (locomotion), alertness, fear, indifference, olfaction and lateral head movements. 3. Biochemical analysis of the raphe dorsalis and caudate nuclei of p-CPA treated animals showed an average drop in serotonin concentration of 77%. Serotonin depletion induced statistically significant changes in the following behaviors in amphetamine-treated cats: locomotion, fear, lateral head movements and alertness. Serotonin depleted cats tested with apomorphine showed significant changes only in olfaction and indifference behaviors. 4. Serotonin appears to play a significant modulatory role in some of the behaviors evoked by amphetamine, specially locomotion. Such role is less evident for the behaviors evoked by apomorphine. |
