Inhibitory effects of dopamine on spinal synaptic transmission via dopamine D1-like receptors in neonatal rats
Inhibitory effects of dopamine on spinal synaptic transmission via dopamine D1-like receptors in neonatal rats
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DOI：
10.1111/j.1476-5381.2011.01815.x
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发表时间：
2012-05-01
影响因子：
7.3
通讯作者：
Ito, S.
中科院分区：
文献类型：
--
作者：
Kawamoto, K.;Otsuguro, K.;Ito, S.
背景和结论从脊髓中下行多巴胺能神经纤维末梢释放的多巴胺可能参与调节功能，如运动和伤害感受。在这里，我们研究了多巴胺对大鼠脊髓突触传递的影响。实验方法脊髓反射电位，单突触反射电位（MSR）和慢腹根电位（sVRP），在新生大鼠的分离脊髓进行了测量。关键词SDS多巴胺在较低浓度（< 1 μ M）下抑制sVRP，sVRP是C纤维诱发的多突触反应，被认为反映了伤害性传递。在较高浓度（> 1 μ M）下，除了有效的sVRP抑制外，多巴胺还使基线电位去极化，并轻微抑制MSR。多巴胺D-1样受体拮抗剂可部分逆转多巴胺对sVRP的抑制作用，而D-2样受体拮抗剂则不能逆转。D-1样受体激动剂SKF 83959和SKF 81297以及内源性多巴胺受体激动剂甲基苯丙胺也可抑制sVRP。甲基苯丙胺也抑制MSR，这是抑制酮色林，5-HT 2A/2C受体拮抗剂。甲基苯丙胺诱导脊髓释放多巴胺和5-HT，表明内源性多巴胺和5-HT的释放抑制sVRP和MSR.CONCLUSION和IMPLITIONsThese结果表明，在较低浓度的多巴胺优先抑制sVRP，这是通过多巴胺D-1样和其他身份不明的受体介导的。多巴胺诱发的抑郁症通过下行多巴胺能通路参与脊髓功能的调节。
BACKGROUND AND PURPOSEDopamine released from the endings of descending dopaminergic nerve fibres in the spinal cord may be involved in modulating functions such as locomotion and nociception. Here, we examined the effects of dopamine on spinal synaptic transmissions in rats.EXPERIMENTAL APPROACHSpinal reflex potentials, monosynaptic reflex potential (MSR) and slow ventral root potential (sVRP), were measured in the isolated spinal cord of the neonatal rat. Dopamine release was measured by HPLC.KEY RESULTSDopamine at lower concentrations (< 1 mu M) depressed sVRP, which is a C fibre-evoked polysynaptic response and believed to reflect nociceptive transmission. At higher concentrations (> 1 mu M), in addition to a potent sVRP depression, dopamine depolarized baseline potential and slightly depressed MSR. Depression of sVRP by dopamine was partially reversed by dopamine D-1-like but not by D-2-like receptor antagonists. SKF83959 and SKF81297, D-1-like receptor agonists, and methamphetamine, an endogenous dopamine releaser, also caused the inhibition of sVRP. Methamphetamine also depressed MSR, which was inhibited by ketanserin, a 5-HT2A/2C receptor antagonist. Methamphetamine induced the release of dopamine and 5-HT from spinal cords, indicating that the release of endogenous dopamine and 5-HT depresses sVRP and MSR respectively.CONCLUSION AND IMPLICATIONSThese results suggested that dopamine at lower concentrations preferentially inhibited sVRP, which is mediated via dopamine D-1-like and other unidentified receptors. The dopamine-evoked depression is involved in modulating the spinal functions by the descending dopaminergic pathways.