Influence of narcotics on luminance and frequency modulated visual evoked potentials in rats
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Quantification of visual function is essential for the impact of disease models and their treatment. Recently, we introduced a chronic implant model to record visual evoked potentials (VEP) in awake Brown–Norway rats. Here, we investigated the hemispheric distribution of VEP after monocular stimulation, the chronic electrode implantation and the influence of commonly used anesthetics. Potentials were recorded by electrodes, implanted epidurally over the superior colliculus. The entire visual field of the rat was stimulated. Flicker stimuli were modulated in luminance with a modulation depth from 5 to 80% at 7.5 Hz and flashes with a modulation depth of >95% in a frequency range of 2.9–38 Hz. Recordings were constant over 9 days. When one eye was blinded, the potentials recorded from the contralateral side were not affected, while the potentials of the ipsilateral side were markedly reduced. Further, potentials of awake animals were compared with those receiving general anesthetics. For one group of rats (n = 8), we administered isoflurane by inhalation in five concentrations. Four different groups (n = 7–11) were given choralhydrate (200 and 400 mg/kg) and the combination of ketamine/xyaline (65/7 or 130/14 mg/kg, respectively) intraperitoneally. Isoflurane depressed the VEP in a concentration-dependent manner. Treatment with chloralhydrate and ketamine/xyaline increased the VEP at low concentrations and depressed it in high concentrations. The new VEP paradigm assesses distinct qualities of contrast vision in rats. All tested narcotics alter VEP amplitudes and can be avoided.
KeywordsVisual evoked potential Rat Chronic electrode implant Modulation depth Flash frequency
Retinal ganglion cells
Visual evoked potentials
The authors wish to thank to Frank Huete and Herbert Graner for their excellent technical support. The study was supported by the Ernst und Berta Grimmke Stiftung, Germany.
- 1.Jehle T, Lagreze WA, Blauth E, Knorle R, Schnierle P, Lucking CH, Feuerstein TJ (2000) Gabapentin-lactam (8-aza-spiro[5, 4]decan-9-on; GBP-L) inhibits oxygen glucose deprivation-induced [3H]glutmate release and is a neuroprotective agent in amodel of acute retinal ischemia. Naunyn Schmiedebergs Arch Pharmacol 362:74–81PubMedCrossRefGoogle Scholar
- 12.Brigell M, Bach M, Barber C, Kawasaki K, Kooijman A (1998) Guidelines for calibration of stimulus and recording parameters used in clinical electrophysiology of vision. calibration standard committee of the international society for clinical electrophysiology of vision (ISCEV). Doc Ophthalmol 95:1–14PubMedCrossRefGoogle Scholar
- 13.Damiani Cavero S, Viera Aleman C, Santos Anzorandia C, Bacallao Gallestey J, Febles Pinar E, Rivero Moreno M (1997) Anesthetic agents and visual evoked potentials in patients undergoing transphenoidal or breast reconstruction surgery. Neurologia (Barcelona, Spain) 12:51–55Google Scholar
- 16.Jehle T, Kunze D, Wingert K, Bach M, Largreze WA (2008) Modulation of contrast depth and flash frequencies: effects on visual evoked potentials recorded in awake, freely moving brown Norway rats. Invest Ophthalmol Vis Sci 48:3756Google Scholar
- 17.Kelly DH (1961) Visual response to time-dependent stimuli. I. Amplitude sensitivity measurements. Rinsho Eiyo 51:422–429Google Scholar