Adult recovered rats submitted to a protein deprivation schedule at perinatal age, were treated with repeated cocaine administration and subsequently evaluated in the open field test. D-R curve using different doses (5, 10 or 15 mg/kg, i.p. daily injections during 16 days) showed a progressive and higher increase of locomotor activity in deprived rats (D) as compared to controls (C) in response to such drug. Moreover, D animals evidenced behavioral sensitization with the lowest dose of cocaine used, this phenomenon was not observed in C rats. In order to correlate this differential sensitization process with neurochemical parameters, we also assessed dopamine levels in different areas of the mesocoticolimbic system such as nucleus accumbens (core and shell) and prefrontal cortex using a microdialysis technique. Preliminary results showed comparable basal values of the dopaminergic function between sensitized C and D rats. A challenge with cocaine produced an unequal increase in extracellular dopamine levels between both experimental groups. These results indicate that a repeated cocaine treatment produced in D animals a progressive sensitization to the stimulant motor effects, in addition to significant changes in the mesocorticolimbic dopaminergic function as compared with C rats.
