Sensitization to the motor stimulant effects of 3,4-methylenedioxypyrovalerone (MDPV) and cross-sensitization to methamphetamine in rats.

Background: In recent years, there has been a dramatic increase in abuse of the synthetic cathinone 3,4-methylenedioxypyrovalerone (MDPV), often in combination with other illicit stimulants.

Purpose: We sought to determine if repeated exposure to MDPV would produce sensitization to the motor stimulant effects of the drug, and whether cross-sensitization would develop with the stimulant effects of methamphetamine (METH).

Study design: Male Sprague-Dawley rats were administered MDPV (1 or 5 mg/kg) or saline once daily for 5 days at 24 hour intervals, or were administered MDPV (1 mg/kg) or saline once daily for 5 days at 48 hour intervals. For cross-sensitization experiments, rats were administered METH (1 mg/kg) or MDPV (1 or 5 mg/kg) once daily for 5 days at 48 hour intervals, and following a 5 day incubation period, were given an acute challenge injection of either MDPV (0.5 mg/kg) or METH (0.5 mg/kg), respectively.

Results: Rats repeatedly administered MDPV (1 mg/kg) every 48 hours, but not every 24 hours, demonstrated increased motor activity when given either a subsequent challenge of MDPV (0.5 mg/kg i.p.) or METH (0.5 mg/kg), indicating the development of behavioral sensitization and cross-sensitization, respectively. Moreover, rats repeatedly administered METH (1 mg/kg) every 48 hours did not exhibit cross-sensitization to the motor stimulating effects of a subsequent challenge with MDPV (0.5 mg/kg).

Conclusion: These results suggest that specific patterns of MDPV administration may lead to lasting changes in behavioral responses to subsequent METH exposure.