Fig. 4.

Dopamine increases xPer2 by activating D2-like dopamine receptors. Three hour treatments with various concentrations of vehicle (white bars), dopamine (bars with diagonal lines), the D2-like agonist quinpirole (gray bars), or the D1-like agonist SKF 38393 (bars with wavy lines) were delivered to eyecups at ZT 10. Eyecups were maintained in constant darkness throughout the experiment. The abundance of xPer2 mRNA was quantitated as in Figure2c, and values were normalized to the vehicle-alone group. The mean value of each group was calculated from five retinas from individual animals. Error bars indicate SEM. Dopamine (100 nm, 500 nm, and 1 μm), quinpirole (100 nm), and SKF 38393 (50 μm) groups were significantly different from the vehicle-alone group (***p < 0.001, *p < 0.05, ANOVA).