Regional differences in dopamine release in the R6/2 mouse caudate putamen.

Huntington's disease (HD) is a fatal neurodegenerative disorder that is characterized by degeneration of the striatum. Here, fast-scan cyclic voltammetry at carbon-fiber microelectrodes was used to uncover regional differences in dopamine (DA) release in the caudate putamen of R6/2 and wild-type control mice. We found a decreasing ventral-to-dorsal gradient in DA release, evoked by a single electrical stimulus pulse, in aged R6/2 mice. Moreover, under more intense stimulation conditions (120 pulses), DA release was significantly attenuated in the dorsal, but not in the ventral caudate. Autoradiography measurements using [3H]WIN 35,428 revealed that the overall density of DA transporter (DAT) protein molecules was significantly less in R6/2 mice compared to WT control mice; however, quadrants of the caudate putamen were not differentially altered in the R6/2 mice. These data collectively suggest that DA release in the dorsal caudate region is more vulnerable with age progression compared to the ventral region.