Effect of intra-amygdala dopaminergic grafts on methamphetamine-induced locomotor activity, extracellular dopamine and dopamine metabolite overflow: a comparison with the effect of intra-accumbens grafts.

The effects of 6-hydroxydopamine lesions of the ventral tegmental area and following intra-amygdala or intra-accumbens dopaminergic (DAergic) grafts on methamphetamine (MAP)-induced locomotor activity were investigated in rats. Intra-accumbens DAergic grafts from rat embryos restored the locomotor hyperactivity response to MAP 5 weeks after grafting, while intra-amygdala grafts did not restore responses by 10 weeks after grafting. Biochemical measurements of extracellular DAergic activity in the amygdala (AMY) by in vivo microdialysis after grafting showed no significant change in the basal levels of dopamine (DA) and partial restoration of metabolite levels. MAP induced an increase of DA efflux and a decrease in dihydroxyphenylacetic acid without a significant change in homovanillic acid, which is the same pattern of response seen in control animals. These biochemical changes are similar to those seen previously after intra-accumbens grafts. The results show that restoration of DAergic activity in the AMY in the presence of DAergic denervation of accumbens does not have an effect on MAP-induced locomotion.