Unaltered detection of opioid stimulus in GluA1−/− mice.

<p>Mice were trained to discriminate 5 mg/kg morphine from saline and then tested for various doses of morphine in a 20-min drug discrimination test session. (<b>A</b>) Dose-response curves for discriminative stimulus effects of morphine; data show morphine-appropriate lever responses expressed as percentage of total responses on both levers. (<b>B</b>) Dose-response curves for response rate-lowering effects of morphine during the dose-response tests. Data are shown as means ± SEM, <i>n</i> = 5–6.