1990 Volume 2 Issue 2 Pages 165-169
Looomotor activity was observed with and without acoustic buzzer stimulation after withdrawal of multiple methamphetamine (MAP) administration. Male Wistar rats were treated repeatedly with intermittent administration of MAP. Increments of MAP were injected every other day (2.5-10 mg/kg, three or two times per day), to induce reverse tolerance without inducing neurotoxicity. The response to acoustic buzzer stimulation was observed using an open field apparatus. MAP induced and maintained reverse tolerance of stereotyped behavior for at least 4 weeks after the last injection. In the saline control group, increased locomotor activity during acoustic stimulation and its suppression after acoustic stimulation were observed. In the MAP group, however, this response to acoustic stimulation was not seen for 4 weeks after withdrawal of the drug. These data suggest that behavioral hyporesponsiveness to acoustic stimulation was induced by repeated MAP treatment, and that this insensitivity to acoustic simulation is a characteristic behavioral change caused by long-term MAP administration.
