Social, motor, and autonomic signs of morphine withdrawal: differential sensitivities to catecholaminergic drugs in mice.

Drugs that predominantly influence catecholamines were used in order to simultaneously determine their ability to alter salient signs of social, motor and autonomic activity during morphine withdrawal, and to compare the sensitivity of each of these signs to these drugs. Cocaine, d-amphetamine, apomorphine and L-dopa increased attack and threat, but did not induce defensive behavior in morphine-withdrawn resident mice who were more responsive to the aggression-enhancing effects of these drugs than placebo control mice. Concurrently measured withdrawal jumping was not affected by these drugs, and the sensitivity to the hypothermic effects of these drugs was reduced. In contrast, clonidine decreased attack and threat behaviors, and morphine-withdrawn mice were more sensitive to this inhibitory influence. But like the stimulant drugs, clonidine did not affect withdrawal jumping, and the hypothermic action of clonidine was attenuated in morphine-withdrawn mice. These findings show that in mice, opiate withdrawal leads to altered attack and threat that is further amplified by catecholaminergic drugs. The present pattern of results indicates differential drug effects on social, motor and autonomic functions when the behaviors are measured 48 h following withdrawal.