Figure 3.

Left: Representative experiment on a control mouse striatal homogenate (average of duplicate measurements) showing competition between dopamine and [³H]domperidone for dopamine D2 receptors. The proportion of high‐affinity D2 receptors, D2^High, was 14% in this tissue, with the average being 16.2 ± 2.5% in all the control tissues. The final concentration of [³H]domperidone was 2 nM. Nonspecific binding was defined by the presence of 1 μM S‐sulpiride. Right: Representative experiment showing competition between dopamine and [³H]domperidone for dopamine D2 receptors in a striatal homogenate from an mGlu2 receptor knockout mouse. The proportion of high‐affinity D2 receptors, D2^High, was 53% in this tissue. The final concentration of [³H]domperidone was 2 nM. (Reproduced from [39] with permission of Wiley‐Liss, Inc.)