title: A chronic implant to record electroretinogram, visual evoked potentials and oscillatory potentials in awake, freely moving rats for pharmacological studies.
abstract: Electroretinogram (ERG), widely used to study the pharmacological effects of drugs in animal models (e.g., diabetic retinopathy), is usually recorded in anesthetized rats. We report here a novel simple method to obtain chronic implantation of electrodes for simultaneous recording at the retinal and cortical levels in freely moving, unanesthetized animals. We recorded cortical (VEPs) and retinal (ERGs) responses evoked by light (flash) stimuli in awake rats and compared the results in the same rats anesthetized with urethane (0.6 mg/kg) before and after the monocular administration of scopolamine methyl bromide (1 per thousand solution). We also compared the retinal responses with those derived from a classic acute corneal electrode. Anesthesia induced consistent changes of several VEP and ERG parameters like an increase of both latency and amplitude. In particular, the analysis of the variation of latency, amplitude, and spectral content of rapid oscillatory potentials could be important for a functional evaluation of the visual system in unanesthetized versus anesthetized animals.
authors.affiliation: Istituto Superiore di Sanità, Via Regina Elena 299, 00161 Roma, Italy.
authors.forename: Irene
authors.initials: I
authors.lastname: Guarino
authors.forename: Stefano
authors.initials: S
authors.lastname: Loizzo
authors.forename: Luisa
authors.initials: L
authors.lastname: Lopez
authors.forename: Antonello
authors.initials: A
authors.lastname: Fadda
authors.forename: Alberto
authors.initials: A
authors.lastname: Loizzo
mesh_terms: D000777:Anesthetics / Q000494:pharmacology; D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology; D004567:Electrodes, Implanted; D004594:Electrophysiology; D004596:Electroretinography / Q000295:instrumentation*; D005074:Evoked Potentials, Visual / Q000187:drug effects / Q000502:physiology*; D010775:Photic Stimulation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012160:Retina / Q000187:drug effects / Q000502:physiology*; D012601:Scopolamine / Q000494:pharmacology; D014520:Urethane / Q000494:pharmacology; D014793:Visual Cortex / Q000187:drug effects / Q000502:physiology*; D014795:Visual Pathways / Q000187:drug effects / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology*
chemical_list: D000777:Anesthetics; D014520:Urethane; D012601:Scopolamine