KMID : 0811720010050050373
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Korean Journal of Physiology & Pharmacology 2001 Volume.5 No. 5 p.373 ~ p.380
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The Inhibitory Effect of Opioid on the Hyperpolarization-Activated Cation Currents in Rat Substantia Gelatinosa Neurons
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Geun Hee Seol
Jun Kim/Sun Hee Cho/Won Ki Kim/Jong Whan Kim/Sang Jeong Kim
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Abstract
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The action of opioid on the hyperpolarization-activated cation current (Ih) in substantia gelatinosa neurons were investigated by using whole-cell voltage-clamp recording in rat spinal brain slices. Hyperpolarizing voltage steps revealed slowly activating currents in a subgroup of neurons. The half-maximal activation and the reversal potential of the current were compatible to neuronal Ih. DAMGO (1¥ìM), a selective- opioid agonist, reduced the amplitude of Ih reversibly. This reduction was dose-dependent and was blocked by CTOP (2¥ìM), a selective ¥ì?opioid antagonist. DAMGO shifted the voltage dependence of activation to more hyperpolarized potential. Cesium (1 mM) or ZD 7288 (100¥ìM) blocked Ih and the currents inhibited by cesium, ZD 7288 and DAMGO shared a similar time and voltage dependence. These results suggest that activation of ¥ì?opioid receptor by DAMGO can inhibit Ih in a subgroup of rat substantia gelatinosa neurons.
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KEYWORD
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