ABSTRACT
<p><b>AIM</b>To observe the effect and mechanism of scopolamine on morphine(Mor)-induced mice dependence.</p><p><b>METHODS</b>The Mor-dependent mice model was established by intraperitoneal (ip) administered Mor for seven days. Pain threshold, times of jump and hippocampus intracellular free calcium ion concentration ([Ca2+]i) were determined by the heat plate test, naloxone (Nal)-precipitated jumping response and flow cytometry, respectively.</p><p><b>RESULTS</b>The pain threshold of Mor-dependent mice decreased significantly while there was a marked increase in times of jump, the rate of jumping animals and hippocampus [Ca2+]i. Co-administered scopolamine, the pain threshold of Mor-dependent mice increased significantly; the number of jump, the rate of jumping animals and hippocampus [Ca2+]i all decreased significantly.</p><p><b>CONCLUSION</b>Scopolamine could antagonize the Mor-induced mice dependence, which could be related to decreasing the levels of brain intracellular free calcium.</p>