Figure 4.

In vivo μN images of the dynamic [Ca²⁺]_i changes in response to cocaine (8 mg/kg, i.p.) in the striatum of D1R-EGFP mice without (a) and with (b) pretreatment of SCH23390 (D1 antagonist). 1, 2, [Ca²⁺]_i images at baseline (t = −5 min) and t = 25 min after cocaine injection. 3, EGFP images of D1R. 4, Ca²⁺ and EGFP images overlapped to identify [Ca²⁺]_i from D1R neurons. 5, Δ[Ca²⁺]_i from individual D1R neurons (dark solid curves) and their averaged change (red bold curve), and from non-D1R cells (dashed curves). Cocaine-evoked [Ca²⁺]_i increase was fast and plateaued at t ≈ 6 min. The dark bold curve corresponds to the control study following saline injection. 6, Δ[Ca²⁺]_i image at t = 25 min. Cocaine-evoked [Ca²⁺]_i increase in striatal D1R-expressing neurons was 8.3 ± 2.4% (n = 14, p < 0.0001); this increase was effectively inhibited by the D1 antagonist down to 0.5 ± 0.2% (n = 12, p < 0.0001).