Neurobiology Laboratory and State Key Laboratory of Biomembrane and Membrane, Biotechnology, College of Life Sciences, Peking University, Beijing 100871, PR China.
Brain Res. 2010 Sep 24;1353:53-9. doi: 10.1016/j.brainres.2010.07.042. Epub 2010 Jul 24.
It has been demonstrated that calcitonin gene-related peptide (CGRP) plays important roles in the modulation of nociception in the nucleus accumbens (NAc) of rats. The present study is performed to explore the possible involvement of opioid receptors in the CGRP-induced antinociception in the NAc of rats. Intra-NAc administration of CGRP induces significant increases in the hindpaw withdrawal latency (HWL) to noxious thermal and mechanical stimulation in rats. Interestingly, the CGRP-induced antinociceptive effects are inhibited by following intra-NAc injection of the opioid receptor antagonist naloxone, suggesting that the opioid receptors are involved in the CGRP-induced antinociception in the NAc of rats. Furthermore, the CGRP-induced antinociception is attenuated by intra-NAc injection of mu-opioid receptor (MOR) antagonist beta-funaltrexamine (beta-FNA) and kappa-opioid receptor (KOR) antagonist nor-binaltorphimine (nor-BNI), but not by delta-receptor (DOR) antagonist naltrindole. In the present study, we also demonstrated that there was no significant difference between the CGRP-induced antinociception and the morphine-induced antinociception in the NAc in rats. The results of the present study demonstrate that both mu- and kappa-opioid receptors are involved in the CGRP-induced antinociception in the NAc of rats.
降钙素基因相关肽（CGRP）在调节大鼠伏隔核（NAc）中的伤害感受中发挥重要作用。本研究旨在探讨阿片受体在 CGRP 诱导的大鼠 NAc 中镇痛作用中的可能参与。NAc 内给予 CGRP 可显著增加大鼠对有害热和机械刺激的后爪撤回潜伏期（HWL）。有趣的是，NAc 内给予阿片受体拮抗剂纳洛酮可抑制 CGRP 诱导的镇痛作用，表明阿片受体参与了大鼠 NAc 中 CGRP 诱导的镇痛作用。此外，NAc 内给予 μ-阿片受体（MOR）拮抗剂β-氟纳曲胺（β-FNA）和 κ-阿片受体（KOR）拮抗剂诺宾那林（nor-BNI）可减弱 CGRP 诱导的镇痛作用，但 δ-受体（DOR）拮抗剂纳曲吲哚（naltrindole）则不能。在本研究中，我们还证明，在大鼠 NAc 中，CGRP 诱导的镇痛作用与吗啡诱导的镇痛作用之间没有明显差异。本研究的结果表明，μ-和 κ-阿片受体都参与了大鼠 NAc 中 CGRP 诱导的镇痛作用。
