Opioid peptide release in the rat hippocampus after kainic acid-induced status epilepticus.
It has been suggested that kainic acid enhances opioid peptide release. However, no direct evidence exists to support this hypothesis. The main aim of the present study was to determine whether such release occurs in the hippocampus of the rat after status epilepticus induced by kainic acid. Microdialysis experiments revealed significant opioid peptide release in the hippocampus 90-150 min (100%) and 270-300 min (50%) after kainic acid-induced status epilepticus. The peptides released were identified by high-performance liquid chromatography linked to radioimmunoassay as Met-enkephalin, Leu-enkephalin, Dynorphin-A (1-6), and Dynorphin-A (1-8). Reduced extracellular opioid peptide immunoreactivity was detected 28 days after status epilepticus (38% compared with control situation). The present results indicate an important activation of opioid peptide systems by kainic acid-induced status epilepticus. In addition, the reduced hippocampal extracellular opioid peptide levels long-term after kainic acid administration could have important implications for the progressive nature of epileptogenesis.
Rocha
L
L
Departamento Farmacobiología, Centro de Investigación y Estudios Avanzados del IPN, DF, Mexico. lrocha@mail.cinvestav.mx
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D000818:Animals; D004195:Disease Models, Animal; D018450:Disease Progression; D015536:Down-Regulation / Q000187:drug effects / Q000502:physiology; D004399:Dynorphins / Q000378:metabolism; D004745:Enkephalins / Q000378:metabolism; D004833:Epilepsy, Temporal Lobe / Q000378:metabolism* / Q000503:physiopathology; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology*; D018698:Glutamic Acid / Q000378:metabolism*; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D007150:Immunohistochemistry; D007608:Kainic Acid / Q000494:pharmacology*; D008297:Male; D018847:Opioid Peptides / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D013226:Status Epilepticus / Q000139:chemically induced / Q000378:metabolism* / Q000503:physiopathology
D004745:Enkephalins; D018690:Excitatory Amino Acid Agonists; D018847:Opioid Peptides; D018698:Glutamic Acid; D004399:Dynorphins; D007608:Kainic Acid