Differential effects of methylphenidate and d-amphetamine on stereotyped behavior in the rat

Different equimolar doses of d-amphetamine and methylphenidate were compared for their potency in eliciting stereotyped behavior in rats. Although at lower doses d-amphetamine appeared more effective in causing stereotyped gnawing, repetitive body movements, and sniffing, at higher doses methylphenidate at certain times caused a greater incidence of gnawing than did d-amphetamine. Understanding these differences and comparing related biochemical correlates may lead to a better definition of mechanisms underlying psychostimulant effects.