Repeated @entity4944 administration and long-term effects on 50-kHz ultrasonic vocalizations: Possible relevance to the motivational and XXXX -stimulating properties of the drug.

@entity35 @entity4944 @entity935 @entity3826
UNASSIGNED: Ultrasonic vocalizations (USVs) of 50kHz are thought to indicate positive affective states in @entity35 , and are increasingly being used to investigate the motivational properties of drugs of abuse. However, previous studies have observed that only dopaminergic psychostimulants of abuse, but not other addictive drugs, stimulate 50-kHz USVs immediately after their administration. This would suggest that 50-kHz USVs induced by addictive dopaminergic psychostimulants might reflect rewarding dopaminergic effect, rather than motivational effect. To elucidate this issue, our study compared the effects of the psychostimulant of abuse @entity4944 and the @entity935 receptor agonist @entity3826 on 50-kHz USVs. @entity35 that received five drug administrations on alternate days in a novel test-cage were first re-exposed to the test-cage 7 days after treatment discontinuation to assess drug-conditioning, and then received a drug challenge. USVs were recorded throughout the experiments together with locomotor activity. To further clarify how @entity4944 and @entity3826 influenced 50-kHz USVs, @entity35 were subdivided into "low" and "high" vocalizers, and time-dependence of drug effects was assessed. @entity4944 and @entity3826 stimulated both 50-kHz USVs and locomotor activity, though they elicited dissimilar changes in these behaviors, depending on drug dose, @entity35 *  individual predisposition to vocalize, and time. Moreover, only @entity4944 -treated @entity35 displayed both sensitized 50-kHz USVs emission and conditioned vocalizations on test-cage re-exposure. These results indicate that the effects of @entity4944 on 50-kHz USVs are not mimicked by a dopaminergic agonist with a low abuse potential, and may further support the usefulness of 50-kHz USVs in the study of the motivational properties of psychoactive drugs.
