Chronic preexposure to methylphenidate cross-sensitizes methamphetamine in male Japanese quail.

An increasing debate exists about the potential of exposure to methylphenidate increasing later risk of drug abuse. The objective of this study was to investigate whether chronic preexposure to methylphenidate would induce cross-sensitization to a subsequent methamphetamine challenge in male Japanese quail. Male quail were treated intraperitoneally with either 5, 10, or 20 mg/kg methylphenidate or saline for 14 days. After a 14-day washout period, birds were challenged with 5.6 mg/kg of methamphetamine. Methylphenidate-induced behavioral sensitization was not evident after 14 days of preexposure. However, locomotor activity was greater during the methamphetamine challenge in birds that were preexposed to a high dose of methylphenidate. The findings suggest that chronic preexposure to methylphenidate may be sufficient to alter later responding to methamphetamine, regardless of whether preexposure resulted in behavioral sensitization.