Naloxone effects on the visual evoked potentials recorded from the main and accessory visual pathways of the cat.
1. The effects produced by repetitive i.v. administration of naloxone (1, 2 or 4 mg/kg) on the visual evoked potentials (VEPs) recorded along the main and accessory visual pathways were investigated in a modified "encéphale isolé" cat preparation. 2. Naloxone provoked a progressive amplitude enhancement and latency reduction of some components, depending on the structure analyzed, the dose used and the number of administrations applied. Electroretinogram (ERG) and N1-P1 VEP components of optic chiasm (OCh), lateral geniculate body (LGB) and visual cortex (VC) did not present significant changes. 3. Late-latency components (more than 200 msec) appeared in the VEPs of LGB and VC, mainly when 4 mg/kg were used. 4. Our results suggest that endogenous opioids have a modulatory role in the processing of sensory information at different levels of the visual system.
Rocha
L
L
Instituto Mexicano de Psiquiatria, División de Investigación en Neurociencias, D.F.
Fernandez-Mas
R
R
Gutierrez
R
R
Martinez
A
A
Pellicer
F
F
Fernandez-Guardiola
A
A
D000818:Animals; D002415:Cats; D003655:Decerebrate State; D004569:Electroencephalography; D004596:Electroretinography; D005074:Evoked Potentials, Visual / Q000187:drug effects*; D005260:Female; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D010775:Photic Stimulation; D014795:Visual Pathways / Q000187:drug effects*
D009270:Naloxone