ACTIVE AND PASSIVE-AVOIDANCE FOLLOWING THE ADMINISTRATION OF SYSTEMIC DSP4, XYLAMINE, OR PARA-CHLOROAMPHETAMINE

Groups of rats were administered either DSP4 (50 mg/kg, i.p.), xylamine (50 mg/kg, i.p.) or p-chloroamphetamine (2 .times. 10 mg/kg, i.p.), either 2 or 1 wk before the testing of 2-way active avoidance. DSP4 and xylamine, the selective noradrenaline (norepinephrine) (NA) neurotoxins, caused a 2-day avoidance impairment but p-chloroamphetamine, the selective 5-hydroxytryptamine (5-HT) neurotoxin, did not do so. Pretreatment with desipramine (20 mg/kg, i.p.) blocked the avoidance impairment caused by DSP4 and xylamine treatment. Neither DSP4 nor xylamine caused any alteration of passive avoidance retention. The biochemical analyses indicated severe NA, but not 5-HT, depletions in the DSP4 and xylamine conditions and drastic 5-HT, but not NA, depletions in the p-chloroamphetamine conditions. These results confirm and extend earlier findings concerning the role of NA in avoidance behavior.