Involvement of the different rat hippocampal glutamatergic receptors in development of seizures induced by soman: an autoradiographic study.
Glutamate (GLU)-receptor subtypes, (quisqualate (QA)-, kainate (KA)-, N- methyl-D-aspartate (NMDA)-receptors) and the phencyclidine sites localized in the ion-channel associated to the NMDA-receptors, were studied by autoradiography in the hippocampus of rats subjected to a convulsive dose of the acetylcholinesterase inhibitor soman (0-, 1,2,2-trimethylpropyl methylphosphonofluoridate). In intoxicated rats, a significant increase in L-[3H]-GLU binding occurred within the first 40 min of seizures in the hippocampal CA3 and CA1 areas. Whereas binding to KA- and NMDA-receptors remained unchanged, L-[3H]-GLU binding to CA3 QA-receptors increased by 31 and 50% respectively after 10 and 40 min of seizures. In CA1, the change in QA-receptors was delayed (+30% after 40 min) and accompanied by an increase in the phencyclidine site binding capacity, reflecting the probable concomitant opening of NMDA ion-channels. These findings confirmed the previously suspected involvement of GLU in the earliest stages of soman-induced seizures, and suggested that, in hippocampus, the primary activation of QA-receptors in the CA3 region could lead to the secondary recruitment of combined non-NMDA (QA) and NMDA mechanisms in CA1.
Lallement
G
G
Unité de Neurotoxicologie, Centre de Recherches du Service de Santé des Armées, La Tronche, France.
Carpentier
P
P
Pernot-Marino
I
I
Baubichon
D
D
Collet
A
A
Blanchet
G
G
D000818:Animals; D001345:Autoradiography; D005971:Glutamates / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter / Q000187:drug effects* / Q000378:metabolism; D012640:Seizures / Q000139:chemically induced*; D012999:Soman / Q000633:toxicity*
D005971:Glutamates; D017470:Receptors, Glutamate; D017981:Receptors, Neurotransmitter; D012999:Soman