ANTAGONISTIC EFFECTS OF LESIONS OF PARAMEDIAN RETICULAR NUCLEUS ON AMPHETAMINE-INDUCED LOCOMOTION AND STRIATAL DOPAMINE RELEASE IN RATS

Systemic administration of amphetamine (1.25 mg/kg) produced increases of locomotion (including horizontal motion, vertical motion, and tota l distance travelled), elevations of turnings (including both clockwis e and anticlockwise) and inhibition of postural freezing in freely mov ing rats. All the afore-mentioned activity measures induced by ampheta mine were suppressed following electrolytic lesions of the paramedian reticular nucleus (PRN) in rat medulla. In addition, the spontaneous l evel of either the locomotor activity, the direction of turnings, or t he postural freezing were slightly but significantly affected by the P RN lesions. In vivo voltammetric data revealed that amphetamine admini stration greatly enhanced the striatal dopamine release. Furthermore, the enhanced dopamine release in corpus striatum produced by amphetami ne were greatly attenuated by PRN lesions. The results indicate that t here exists a PRN-striatal dopamine link in rat brain which mediates t he amphetamine-induced increases of locomotion and turnings, as well a s decreases of postural freezing.