Synergistic action of corticosterone on kainic acid-induced electrophysiological alterations in the hippocampus.
The present study investigates the effect of overexposure to high doses of the stress hormone corticosterone (CORT) on the electrophysiological changes produced in the hippocampus after local microinjection of KA. Extracellular recordings were performed in the CA1 area of mouse hippocampal slices prepared after a 7-day recovery period following KA microinfusion alone or combined with 3 days overexposure to CORT. The results showed that CORT shifts the KA response profile approximately 40-fold, since animals treated with a non-toxic dose of 0.01 microgram KA and CORT exhibited epileptic activity and a shift on the paired-pulse response similar to that observed in animals treated with high doses of KA (0.4 microgram). This synergistic action of CORT on the electrophysiological changes induced by KA was antagonized by the antiglucocorticoid RU486 whereas the antimineralocorticoid spironolactone was ineffective. These results suggest that CORT may play an important role in modulating the severity of KA-induced seizures in the hippocampal structure probably by GR-receptor mediated action.
Talmi
M
M
Laboratoire de Neurobiologie des Comportements, CNRS URA 372, Université de Provence, Marseille, France.
Carlier
E
E
Bengelloun
W
W
Soumireu-Mourat
B
B
D000818:Animals; D003345:Corticosterone / Q000494:pharmacology*; D004357:Drug Synergism; D004827:Epilepsy / Q000139:chemically induced / Q000503:physiopathology; D005071:Evoked Potentials / Q000187:drug effects; D006624:Hippocampus / Q000187:drug effects* / Q000503:physiopathology; D066298:In Vitro Techniques; D007608:Kainic Acid / Q000494:pharmacology*; D051379:Mice; D008807:Mice, Inbred BALB C; D015735:Mifepristone / Q000494:pharmacology; D009498:Neurotoxins / Q000494:pharmacology*
D009498:Neurotoxins; D015735:Mifepristone; D007608:Kainic Acid; D003345:Corticosterone