Dual Diagnosis

Methylphenidate (MPD) is a readily prescribed drug for the treatment of attention defi cit hyperactivity disorder (ADHD)

and moreover it is used and abused by youths and young adults for its cognitive enhancing eff ects and recreation.

Repetitive MPD exposure leads to an augmented behavioral response referred to as behavioral sensitization, an experimental

marker for a drugs ability to elicit dependence. Th ere is evidence that dopamine (DA) and GABA are key players in the acute and

chronic MPD eff ect, however the exact roles of DA and GABA in the eff ects elicited by MPD are still debated. Psychostimulants

such as cocaine and amphetamine exert their eff ects on brain regions known as the motive or reward circuit. Since MPD has

functionally and structurally similar properties as amphetamine and cocaine, it is important to fi nd out whether MPD elicits

its eff ect on some of the motive circuit nuclei such as the nucleus accumbens (NAc), prefrontal cortex (PFC), caudate nucleus

(CN), and ventral tegmental area (VTA) and the role of DA and GABA in MPD eff ects. Th e study lasted for 12-21 consecutive

days. Seventeen groups of male SD rats were used to produce electrical and chemical lesions in the VTA, NAc, PFC, and CN,

and GABA, DA D1 and D2 antagonists were used. Data will show the role of the VTA, NAc, PFC, and CN and the eff ects of

DA and GABA on acute and chronic MPD action.