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.

Dextromethorphan diminishes methamphetamine's effects

Dextromethorphan is a cough suppressant found in Robitussin-DM and Mucinex-DM and binds to a number of sites in the brain related to drug abuse and dependence, including opioid receptors, sigma receptors, glutamate receptors and neurotransmitter transporters.  Pao-Pao Yang and colleagues recently published a research article in the journal Synapse indicating that dextromethorphan could be a treatment for craving for methamphetamine craving.  In their experiment, dextromethorphan microinjection into brain regions associated with drug abuse and dependence (the nucleus accumbens and ventral tegmental area) decreased methamphetamine-seeking during a methamphetamine withdrawal period.

Reference - Yang PP et al (2012) Post-treatment of dextromethorphan on methamphetamine-induced drug-seeking and behavioral sensitization in rats. Synapse