Protection by imidazol(ine) drugs and agmatine of glutamate-induced neurotoxicity in cultured cerebellar granule cells through blockade of NMDA receptor

Br J Pharmacol. 1999 Jul;127(6):1317-26. doi: 10.1038/sj.bjp.0702679.


This study was designed to assess the potential neuroprotective effect of several imidazol(ine) drugs and agmatine on glutamate-induced necrosis and on apoptosis induced by low extracellular K+ in cultured cerebellar granule cells. Exposure (30 min) of energy deprived cells to L-glutamate (1-100 microM) caused a concentration-dependent neurotoxicity, as determined 24 h later by a decrease in the ability of the cells to metabolize 3-(4,5-dimethythiazol-2-yl)-2,5-diphenyltetrazoliumbromide (MTT) into a reduced formazan product. L-glutamate-induced neurotoxicity (EC50=5 microM) was blocked by the specific NMDA receptor antagonist MK-801 (dizocilpine). Imidazol(ine) drugs and agmatine fully prevented neurotoxicity induced by 20 microM (EC100) L-glutamate with the rank order (EC50 in microM): antazoline (13)>cirazoline (44)>LSL 61122 [2-styryl-2-imidazoline] (54)>LSL 60101 [2-(2-benzofuranyl) imidazole] (75)>idazoxan (90)>LSL 60129 [2-(1,4-benzodioxan-6-yl)-4,5-dihydroimidazole](101)>RX82 1002 (2-methoxy idazoxan) (106)>agmatine (196). No neuroprotective effect of these drugs was observed in a model of apoptotic neuronal cell death (reduction of extracellular K+) which does not involve stimulation of NMDA receptors. Imidazol(ine) drugs and agmatine fully inhibited [3H]-(+)-MK-801 binding to the phencyclidine site of NMDA receptors in rat brain. The profile of drug potency protecting against L-glutamate neurotoxicity correlated well (r=0.90) with the potency of the same compounds competing against [3H]-(+)-MK-801 binding. In HEK-293 cells transfected to express the NR1-1a and NR2C subunits of the NMDA receptor, antazoline and agmatine produced a voltage- and concentration-dependent block of glutamate-induced currents. Analysis of the voltage dependence of the block was consistent with the presence of a binding site for antazoline located within the NMDA channel pore with an IC50 of 10-12 microM at 0 mV. It is concluded that imidazol(ine) drugs and agmatine are neuroprotective against glutamate-induced necrotic neuronal cell death in vitro and that this effect is mediated through NMDA receptor blockade by interacting with a site located within the NMDA channel pore.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agmatine / pharmacology*
  • Animals
  • Antazoline / pharmacology
  • Benzofurans / pharmacology
  • Cell Line
  • Cells, Cultured
  • Cerebellum / cytology
  • Cerebellum / drug effects*
  • Cerebellum / pathology
  • Dioxanes / pharmacology*
  • Dizocilpine Maleate / metabolism
  • Dizocilpine Maleate / pharmacology
  • Dose-Response Relationship, Drug
  • Electrophysiology
  • Glutamic Acid / pharmacology*
  • Humans
  • Idazoxan / analogs & derivatives
  • Idazoxan / pharmacology
  • Imidazoles / pharmacology*
  • Neuroprotective Agents / pharmacology*
  • Patch-Clamp Techniques
  • Potassium / pharmacology
  • Radioligand Assay
  • Rats
  • Rats, Wistar
  • Receptors, N-Methyl-D-Aspartate / antagonists & inhibitors*
  • Receptors, N-Methyl-D-Aspartate / genetics
  • Receptors, N-Methyl-D-Aspartate / physiology
  • Styrenes / pharmacology*


  • 2-(1,4-benzodioxan-6-yl)-4,5-dihydroimidazole
  • 2-styryl-2-imidazoline
  • Benzofurans
  • Dioxanes
  • Imidazoles
  • LSL 60101
  • Neuroprotective Agents
  • Receptors, N-Methyl-D-Aspartate
  • Styrenes
  • Glutamic Acid
  • Dizocilpine Maleate
  • Agmatine
  • imidazole
  • Antazoline
  • 2-methoxyidazoxan
  • cirazoline
  • Potassium
  • Idazoxan