Inter-individual diversity and intra-individual stability of amphetamine-induced sensitization of frequency-modulated 50-kHz vocalization in Sprague–Dawley rats

Abstract

Vulnerability to sensitization of frequency-modulated 50-kHz vocalization response of Sprague-Dawley rats to amphetamine, which supposedly reflects rats' propensity for amphetamine dependence, shows large inter-individual diversity. Resistance to this effect, which is evident in a majority of the rats, cannot be overcome even with prolonged intermittent drug treatment under the conditions (novelty) that promote sensitization.