Effect of methamphetamine on the locomotor activity in the 6-OHDA dorsal hippocampus lesioned rat.

The present studies were carried out to examine a possible role of hippocampal dopamine in the hyperactivity induced by methamphetamine. For this purpose, 6-hydroxydopamine (6-OHDA) lesion of the dorsal hippocampus (D-HPC) was made in desmethylimipramine pretreated rats in order to specifically destroy dopamine neurons. D-HPC lesions produced a large (96%) and selective depletion of content of dopamine in the D-HPC. This lesion did not change spontaneous locomotion and rearing behavior. The 6-OHDA lesioned rat produced a blockade of the increase in locomotor activity induced by 1.0 and 2.0 mg/kg of methamphetamine. In contrast, the 6-OHDA lesion of the D-HPC failed to influence the methamphetamine-induced rearing activity. These results indicate that dopamine neurons in the D-HPC may have some role in methamphetamine-induced locomotion, but not in methamphetamine-induced rearing.