Naloxone facilitates sensory precipitation of focal and generalized seizures: evoked potentials and power spectral analysis in the cat.
To analyze the role of endogenous opioids on epileptogenesis the effect of repeated doses of naloxone alone (NA) (2, 4, and 8 mg/kg every 15 min) or along with intermittent photic stimulation (NPS) (1, 3, and 10 Hz) was tested on acute "Encephale isolé" cats. The electrical activity recordings of sensorimotor cortex (SMC), visual cortex, and right and left amygdalae revealed progressive changes as naloxone was administered: (A) slow spindle activity (4-6 Hz) in SMC, (B) 12 Hz rhythmic activity in both amygdalae, (C) generalized paroxysms, and (D) spontaneous tonic-clonic electrographic seizures. These changes occurred in both experimental groups (NA, NPS), and their onset was dose-related. Photic stimulation precipitated these phenomena. The amplitude of the visual evoked potential components (N1-P1, P1-N2, N2-P2) and power spectral analysis of spontaneous and evoked activity underwent progressive changes. Our results confirm a facilitatory effect of naloxone on epileptogenesis and suggest a possible role of endogenous opioids in this process and on sensory pathways' excitability.
D000679:Amygdala / Q000503:physiopathology; D000818:Animals; D002415:Cats; D003655:Decerebrate State; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography; D004828:Epilepsies, Partial / Q000503:physiopathology*; D005074:Evoked Potentials, Visual; D005260:Female; D008297:Male; D009044:Motor Cortex / Q000503:physiopathology; D009270:Naloxone / Q000494:pharmacology*; D010775:Photic Stimulation; D013003:Somatosensory Cortex / Q000503:physiopathology; D014793:Visual Cortex / Q000503:physiopathology
D009270:Naloxone