ABSTRACT
<p><b>AIM</b>To explore effects of intrathecal injection of U0126 on morphine withdrawal response and the spinal Phospho-CREB expression in morphine-induced withdrawal rats.</p><p><b>METHODS</b>All the rats were divided into 5 groups: control group, dependence group, withdrawal group, U0126 group (5 microg, it) and DMSO group. Morphine withdrawal score, touch evoked agitation scores(TEA score), immunohistochemical and Western-blotting technique were used to evaluate morphine withdrawal response and the expression of Phospho-CREB in the spinal cord.</p><p><b>RESULTS</b>Intrathecal injection of MEK inhibitor U0126 significantly alleviated morphine withdrawal symptoms. Morphine withdrawal scores in U0126 group (22.5 +/- 4.09) were significantly lower than that of withdrawal group (28.6 +/- 4.89, P < 0.05). TEA score of withdrawal group was 13.5 +/- 2.55, which was significantly higher than that of U0126 group (10.0 +/- 2.76, P < 0.05). Phospho-CREB positive neurons in the spinal dorsal horn of withdrawal group were 380 +/- 71, which is higher than that of U0126 group (293 +/- 47, P < 0.05). Compared with withdrawal group, level of Phospho-CREB protein detected by Western blot in spinal cord of U0126 group was significantly lower.</p><p><b>CONCLUSION</b>MEK inhibitors U0126 could suppress expression of Phospho-CREB in the spinal cord.</p>