Morphine–nicotine interaction in conditioned place preference in mice after chronic nicotine exposure

详细信息	查看全文 | 推荐本文 |

• 作者：Tanja Vihavainen ; Marjo Piltonen ; Raimo K. Tuominen ; Esa R. Korpi ; Liisa Ahtee
• 关键词：Nicotine ; Morphine ; Cross-sensitization ; Conditioned place preference ; [³H]DAMGO ; [³⁵S]GTPγ ; S
• 刊名：European Journal of Pharmacology
• 出版年：2008
• 期刊代码：24_00142999
• 类别：neu
• 出版时间：10 June 2008
• 卷：587
• 期：1-3
• 页码：169-174
• 文件大小：283 K

摘要

Previously we found that morphine's effects on locomotor activity and brain dopamine metabolism were enhanced in mice after cessation of 7-week oral nicotine treatment. In the present experiments we show that such chronic nicotine exposure cross-sensitizes NMRI mice to the reinforcing effect of morphine in the conditioned place preference paradigm. The nicotine-treated mice developed conditioned place preference after being conditioned twice with morphine 5 mg/kg s.c. whereas in control mice a higher dose (10 mg/kg) of morphine was required. Since the reinforcing effect of morphine is mediated via µ-opioid receptors we used [³H]DAMGO autoradiography to study whether the number (B_max) or affinity (K_D) of µ-opioid receptors in the mouse brain are affected following chronic nicotine exposure. However, no changes were found in the number or affinity of µ-opioid receptors in any of the brain areas studied. Neither did we find alterations in the functional activity of µ-opioid receptors studied by [³⁵S]GTPγS-binding. In conclusion, chronic oral nicotine treatment augments the reinforcing effects of morphine in mice, and this cross-sensitization does not seem to be mediated by µ-opioid receptors.