Mechanism of Glutamate-inducedCa2+i Increase in Substantia Gelatinosa Neurons of Juvenile Rats.
- Author:
Sung Jun JUNG
1
;
Jeong Sook CHOI
;
Jiyeon KWAK
;
Jun KIM
;
Jong Whan KIM
;
Sang Jeong KIM
Author Information
1. Department of Physiology, College of Medicine, Kangwon National University, Chunchon, Korea. sangjkim@kangwon.ac.kr
- Publication Type:Original Article
- Keywords:
Substantia gelatinosa neuron;
Glutamate;
IntracellularCa (2+) concentration;
NMDA receptor;
AMPA receptor;
Metabotropic glutamate receptor
- MeSH:
6-Cyano-7-nitroquinoxaline-2,3-dione;
Animals;
Central Nervous System;
Fura-2;
Glutamic Acid;
Membranes;
N-Methylaspartate;
Neurons*;
Rats*;
Receptors, AMPA;
Receptors, Glutamate;
Receptors, Metabotropic Glutamate;
Spinal Cord;
Substantia Gelatinosa*
- From:The Korean Journal of Physiology and Pharmacology
2003;7(2):53-58
- CountryRepublic of Korea
- Language:English
-
Abstract:
The glutamate receptors (GluRs) are key receptors for modulatory synaptic events in the central nervous system. It has been reported that glutamate increases the intracellularCa (2+) concentration ([Ca2+]i) and induces cytotoxicity. In the present study, we investigated whether the glutamate-induced[Ca2+]i increase was associated with the activation of ionotropic (iGluR) and metabotropic GluRs (mGluR) in substantia gelatinosa neurons, using spinal cord slice of juvenile rats (10~21 day) .[Ca2+]i was measured using conventional imaging techniques, which was combined with whole-cell patch clamp recording by incorporating fura-2 in the patch pipette. At physiological concentration of extracellularCa (2+), the inward current and[Ca2+]i increase were induced by membrane depolarization and application of glutamate. Dose-response relationship with glutamate was observed in bothCa (2+) signal and inward current. The glutamate-induced[Ca2+]i increase at holding potential of 70 mV was blocked by CNQX, an AMPA receptor blocker, but not by AP-5, a NMDA receptor blocker. The glutamate-induced[Ca2+]i increase inCa (2+) free condition was not affected by iGluR blockers. A selective mGluR (group I) agonist, RS-3, 5-dihydroxyphenylglycine (DHPG), induced[Ca2+]i increase at holding potential of 70 mV in SG neurons. These findings suggest that the glutamate-induced[Ca2+]i increase is associated with AMPA-sensitive iGluR and group I mGluR in SG neurons of rats.
