Four sham and 4 6-OHDA-lesioned mice were used for stereological estimation of the number of D1, D2 and D1/D2 MSNs. In each mouse, 6 sections were selected from the pre-commissural striatum. Three adjacent sections were selected at 0.26 mm from bregma and 3 others at 1.10 mm. Three more sections were taken at −0.94 mm from bregma. These sections were used to estimate the number of D1, D2 and D1/D2 MSNs in the pre-commissural (0.26 mm from bregma) and post-commissural striatum (−0.94 mm from bregma), as well as in the Acb (1.10 mm from bregma), with an unbiased stereological method using a confocal microscope equipped with a digital camera and a motorized stage controlled by a computer running the StereoInvestigator software (v. 7.00.3; MicroBrightField, Colchester, VT, USA). First, on each section, striatal contour was traced and 4 striatal sectors were delineated corresponding to a dorsolateral, dorsomedial, ventrolateral and ventromedial sectors (Fig. 4). The Acb was divided into its core and shell compartments based on CB-immunostained adjacent sections.
