Can rats "tell us" they want methamphetamine by "talking"?

A research group at the Medical University of South Carolina recently published a paper in the journal Behavioural Brain Research on ultrasonic vocalizations (USVs) and methamphetamine self-administration.  Rats were trained to make a response to receive a methamphetamine infusion, but then responses did not yield drug delivery.  The authors observed differences in vocalizations from when methamphetamine was available and when it was not available.  Moreover, different vocalizations were observed when cues associated with methamphetamine were presented, than when other cues were presented.  These data suggest drug addiction researchers could use USVs to study the subjective states (e.g., "craving") associated with methamphetamine reinforcement.

Reference - S.V. Mahler et al. (2012) A rodent “Self-Report” measure of methamphetamine craving? Rat ultrasonic vocalizations during methamphetamine self-administration, extinction, and reinstatement . Behavioural Brain Research  , in press.

"Bath Salts" and methamphetamine have a different toxicological profile?

There have been a number of news reports recently about people who display abnormal aggression while using "bath salts".  The putative active ingredient in these preparations is mephedrone, a combination of methamphetamine and cathinone.  While methamphetamine is neurotoxic to the terminal button of striatal neurons, a report in The Journal of Neurochemistry suggests that mephedrone lacks methamphetamine's impact in this model.   Despite the similarities between mephedrone and methamphetamine, mephedrone does not produce methamphetamine's change in dopamine, dopamine transporter, or tyrosine hydroxylase.

Reference - Angoa-Perez et al. (2012). Mephedrone, an abused psychoactive component of 'bath salts' and methamphetamine congener, does not cause neurotoxicity to dopamine nerve endings of the striatum  J Neurosci 120(6): 1097