The inhibitory effect of opioid on the hyperpolarization-activated cation currents in rat substantia gelatinosa neurons.
- Author:
Geun Hee SEOL
1
;
Jun KIM
;
Sun Hee CHO
;
Won Ki KIM
;
Jong Whan KIM
;
Sang Jeong KIM
Author Information
1. Department of Physiology, Kangwon National University College of Medicine, Hyoja 2-dong, Chunchon, 200-701, South Korea. sangjkim@kangwon.ac.kr
- Publication Type:Original Article
- MeSH:
Animals;
Brain;
Cesium;
Enkephalin, Ala(2)-MePhe(4)-Gly(5)-;
Neurons*;
Rats*;
Substantia Gelatinosa*
- From:The Korean Journal of Physiology and Pharmacology
2001;5(5):373-380
- CountryRepublic of Korea
- Language:English
-
Abstract:
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 muM), a selective-opioid agonist, reduced the amplitude of Ih reversibly. This reduction was dose-dependent and was blocked by CTOP (2 muM), a selective mu-opioid antagonist. DAMGO shifted the voltage dependence of activation to more hyperpolarized potential. Cesium (1 mM) or ZD 7288 (100 muM) 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 mu-opioid receptor by DAMGO can inhibit Ih in a subgroup of rat substantia gelatinosa neurons.
