Methamphetamine's Action on Brain-Stimulation Reward Threshold and Stereotypy

The effects of methamphetamine (MAMP) on the threshold for brain-stimulation reward (BSR) were determined in 9 male F-344 rats. MAMP significantly lowered the BSR threshold at doses of 0.6-1.0 mg/kg. Marked head movement and stereotypic sniffing behavior appeared at doses >= 2.0 mg/kg. Following repeated exposure to MAMP, there was a shift in the dose-response curve to the left, and stereotypy was observed at 0.5 mg/kg. Results suggest that the reinforcing property of MAMP is mediated, at least in part, through the same reward pathway as other abused psychomotor stimulants and that repeated but spaced exposure results in sensitization that is reflected in both sensitivity to BSR and stereotypic behavior.