Magazanik L G, Fedorova I M
I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, Russian Academy of Sciences. Thorez pr. 44, S-Petersburg, 194223, Russia.
Neurochem Res. 2003 Apr;28(3-4):617-24. doi: 10.1023/a:1022893928104.
The effects of adenosine and ATP were studied on blowfly larvae Calliphora vicina neuromuscular preparation. Adenosine diminished (IC50 = 40 +/- 3 microM) the amplitude of nerve-evoked postsynaptic currents (EPSCs) and slightly decreased the frequency of spontaneous currents without affecting their amplitude. EPSCs were slightly reduced by ATP, and this effect was prevented by concanavalin A. Presynaptic inhibition by adenosine was temperature-dependent and insensitive to pertussis toxin. A1 agonists of vertebrate adenosine receptor CPA and NECA failed to reproduce the effect of adenosine, and 2-CADO enhanced the EPSCs. A1 antagonist DPCPX competitively inhibited adenosine action. A2 agonist DPMA potentiated EPSCs, and its effect was abolished by A2 antagonist DMPX. Adenosine and ATP failed to affect the nonquantal release of glutamate. The results show for the first time the presence of presynaptic adenosine receptors regulating transmitter release at insect motor nerve terminals and point to differences in pharmacological properties of adenosine receptor subtypes in insects and vertebrates.
研究了腺苷和三磷酸腺苷（ATP）对绿蝇幼虫（红头丽蝇）神经肌肉标本的作用。腺苷降低了（半数抑制浓度[IC50]=40±3微摩尔）神经诱发的突触后电流（兴奋性突触后电流[EPSCs]）的幅度，并略微降低了自发电流的频率，而不影响其幅度。ATP使EPSCs略有降低，伴刀豆球蛋白A可阻止此效应。腺苷的突触前抑制作用具有温度依赖性，且对百日咳毒素不敏感。脊椎动物腺苷受体A1激动剂环戊腺苷（CPA）和5'-N-乙基-烟酰胺腺嘌呤二核苷酸（NECA）未能重现腺苷的作用，而2-氯腺苷（2-CADO）增强了EPSCs。A1拮抗剂8-环戊基-1,3-二丙基黄嘌呤（DPCPX）竞争性抑制腺苷的作用。A2激动剂二丙基甲基黄嘌呤（DPMA）增强了EPSCs，其作用被A2拮抗剂1,3-二甲基黄嘌呤（DMPX）消除。腺苷和ATP未能影响谷氨酸的非量子释放。结果首次表明，昆虫运动神经末梢存在调节递质释放的突触前腺苷受体，并指出昆虫和脊椎动物腺苷受体亚型在药理学特性上存在差异。
