Jerlhag Elisabet, Grøtli Morten, Luthman Kristina, Svensson Lennart, Engel Jörgen A
Institute of Physiology and Pharmacology, Department of Pharmacology, Göteborg University, Box 431, SE 405 30 Göteborg, Sweden.
Alcohol Alcohol. 2006 Sep-Oct;41(5):486-93. doi: 10.1093/alcalc/agl049. Epub 2006 Jun 23.
The stimulatory, rewarding, and dopamine (DA)-enhancing effects of ethanol may involve central nicotinic acetylcholine receptors (nAChR), especially those located in the ventral tegmental area (VTA). Identifying the subunit composition that mediates these effects of ethanol would increase the understanding of the neurochemical basis underlying the addictive properties of ethanol. In the present series of experiments, the role of the alpha(3)beta(2)() and/or beta(3)() and/or alpha(6)() subunits of the nAChR for the stimulatory and DA-enhancing effects of ethanol was investigated by using alpha-conotoxin MII (alphaCtxMII), selective to the alpha(3)beta(2)() and/or beta(3)() and/or the alpha(6)() subunits of the nAChR, and the alpha-conotoxin PIA-analogue (alphaCtxPIA-analogue), suggested to be selective to the alpha(6)(*) subunits.
alphaCtxMII and the alphaCtxPIA-analogue were synthesized using a modified literature procedure. The purity and identity of the peptides were confirmed with HPLC and FAB-MS analyses, respectively. Locomotor activity and in vivo microdialysis in freely moving mice were used.
alphaCtxMII and the alphaCtxPIA-analogue were synthesized in good yields (>95%; >90%). In addition, we found that synthesized alphaCtxMII antagonized ethanol-induced locomotor stimulation, which confirms our previous results with the commercially available alphaCtxMII. Furthermore, the synthesized alphaCtxPIA-analogue, assumably also selective for alpha(6)(*) subunits of the nAChR, did neither antagonize the stimulatory nor the accumbal DA-enhancing effects of ethanol.
These results indicate that alphaCtxMII- but not alphaCtxPIA-analogue-sensitive receptors, i.e. the alpha(3)beta(2)() and/or beta(3)() rather than the alpha(6)(*) subunits of the nAChR, appear to be of greater importance for these effects of ethanol and that these subunits could constitute neurochemical targets for developing new drugs for the treatment of alcohol dependence.
乙醇的刺激、奖赏及多巴胺（DA）增强作用可能涉及中枢烟碱型乙酰胆碱受体（nAChR），尤其是位于腹侧被盖区（VTA）的受体。确定介导乙醇这些作用的亚基组成将增进对乙醇成瘾特性背后神经化学基础的理解。在本系列实验中，通过使用对nAChR的α(3)β(2)()和/或β(3)()和/或α(6)()亚基具有选择性的α-芋螺毒素MII（αCtxMII）以及被认为对α(6)()亚基具有选择性的α-芋螺毒素PIA类似物（αCtxPIA-类似物），研究了nAChR的α(3)β(2)()和/或β(3)()和/或α(6)(*)亚基在乙醇的刺激和DA增强作用中的作用。
使用改良的文献方法合成αCtxMII和αCtxPIA-类似物。分别通过高效液相色谱（HPLC）和快原子轰击质谱（FAB-MS）分析确认肽段的纯度和同一性。使用自由活动小鼠的自主活动和体内微透析技术。
αCtxMII和αCtxPIA-类似物的合成产率良好（>95%；>90%）。此外，我们发现合成的αCtxMII拮抗乙醇诱导的自主活动兴奋，这证实了我们之前使用市售αCtxMII得到的结果。此外，可以推测对nAChR的α(6)(*)亚基也具有选择性的合成αCtxPIA-类似物，既不拮抗乙醇的刺激作用，也不拮抗乙醇对伏隔核DA的增强作用。
这些结果表明，对乙醇这些作用而言，对αCtxMII敏感而非对αCtxPIA-类似物敏感的受体，即nAChR的α(3)β(2)()和/或β(3)()亚基而非α(6)(*)亚基似乎更为重要，并且这些亚基可能构成开发治疗酒精依赖新药的神经化学靶点。
