Effects of methamphetamine on blood flow in the caudate-putamen after lesions of the nigrostriatal dopaminergic bundle in the rat.

Methamphetamine was given to rats with unilateral 6-hydroxydopamine lesions of the nigrostriatal dopaminergic bundle. In these animals local cerebral blood flow, measured autoradiographically with [14C]iodoantipyrine as the diffusible tracer, was more than twice as high in the denervated caudate-putamen as compared to control. Measurements of local glucose consumption with the [14C]deoxyglucose technique showed no corresponding change in local metabolic rate. In fact, glucose consumption was lower in the caudate-putamen on the lesion side. The results show that the amphetamine-induced increase in cerebral blood flow does not require an inact nigrostriatal dopaminergic system. Furthermore, dopamine released by amphetamine seems to constrict the vessels and reduce the blood flow in the caudate-putamen.