Inhibition of evoked glutamate release by the neuroprotective 5-HT(1A) receptor agonist BAY x 3702 in vitro and in vivo.
Brain ischemia provoked by stroke or traumatic brain injury induces a massive increase in neurotransmitter release, in particular of the excitotoxin glutamate. Glutamate triggers a cascade of events finally leading to widespread neuronal cell damage and death. The aminomethylchroman derivative BAY x 3702 is a novel neuroprotectant which shows pronounced beneficial effects in various animal models of ischemic brain injury. As shown previously BAY x 3702 binds to 5-HT(1A) receptors of different species in subnanomolar range and is characterized as a full receptor agonist. In this study we investigated the influence of BAY x 3702 on potassium-evoked glutamate release in vitro and ischemia-induced glutamate release in vivo. In rat hippocampal slices BAY x 3702 inhibited evoked glutamate release in a dose-dependent manner (IC(50)=1 microM). This effect was blocked by the selective 5-HT(1A) receptor antagonist WAY 100635, indicating that BAY x 3702 specifically acts via 5-HT(1A) receptors. In vivo, release of endogenous aspartate and glutamate was measured in the cortex of rats by microdialysis before and after onset of permanent middle cerebral artery occlusion. Single dose administration of BAY x 3702 (1 microg/kg or 10 microg/kg i.v.) immediately after occlusion reduced the increase and total release of extracellular glutamate by about 50% compared to non-treated animals, whereas the extracellular aspartate levels were not significantly affected. Inhibition of glutamate release may therefore contribute to the pronounced neuroprotective efficacy of BAY x 3702 in various animal models of ischemic brain damage.
Mauler
F
F
Bayer AG, PH-R CNS, Aprather Weg 18a, 42096, Wuppertal, FRG. frank.mauler.fm@bayer-ag.de
Fahrig
T
T
Horváth
E
E
Jork
R
R
D000818:Animals; D001224:Aspartic Acid / Q000378:metabolism; D001578:Benzopyrans / Q000494:pharmacology*; D002545:Brain Ischemia / Q000188:drug therapy*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D005110:Extracellular Space / Q000378:metabolism; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000098:blood supply / Q000378:metabolism; D020244:Infarction, Middle Cerebral Artery / Q000188:drug therapy; D008297:Male; D017551:Microdialysis; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000378:metabolism*; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D009435:Synaptic Transmission / Q000187:drug effects; D013844:Thiazoles / Q000494:pharmacology*
D001578:Benzopyrans; D018696:Neuroprotective Agents; D011985:Receptors, Serotonin; D044263:Receptors, Serotonin, 5-HT1; D017366:Serotonin Receptor Agonists; D013844:Thiazoles; C111221:repinotan hydrochloride; D001224:Aspartic Acid; D018698:Glutamic Acid