[The electroretinogram (ERG) of the mouse: normal values, optimal stimulation and recording].
OBJECTIVE
The electroretinogram (ERG) is an appropriate method to evaluate the retinal function in a variety of animal models. In this study we present suitable conditions of stimulation and recording in the dark-adapted mouse.


METHODS
Mice (n = 15) were dark-adapted during 14 hours and anesthetized with a single intraperitoneal injection of xylazine/ketamine. Pupils were dilated and a d.c.-silk-silver electrode or a AgCl-contact-lens electrode was placed on the cornea. The electroretinogram (ERG) was obtained by Ganzfeld stimulation over a range of 6 log units of intensity (8 x 10(-2) - 8 x 104 cd/m2). Intensity, duration and the interval of the light stimuli were varied separately.


RESULTS
Reproducible values of the intensity-response functions are obtained for the a-, b- and c-waves of the ERG under well controlled adaptation- and stimulus-conditions. C-wave amplitudes are best evaluated using d.c.-recording and a stimulus duration of 4 seconds. The position of the d.c.-silk-silver electrode on the cornea can affect the ERG-amplitudes. Using a contact-lens electrode, the recorded b-wave amplitudes are on average 20% below those recorded with a centrally positioned d.c.-silk-silver electrode. Stimulus-intervals of at least 60 seconds are recommended at high intensities.


CONCLUSIONS
An unequivocal assessment of retinal function requires reproducible ERG-values over a wide range of intensities. To obtain these, well controlled and standardized experimental conditions are required.
Kueng-Hitz
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N
Universitäts-Augenklinik, CH-8091 Zürich.
Rol
P
P
Niemeyer
G
G
D000818:Animals; D003623:Dark Adaptation / Q000502:physiology; D004566:Electrodes; D004596:Electroretinography / Q000295:instrumentation / Q000662:veterinary*; D006801:Humans; D051379:Mice / Q000502:physiology*; D008954:Models, Biological; D010775:Photic Stimulation / Q000295:instrumentation; D012016:Reference Values; D015203:Reproducibility of Results; D012160:Retina / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted / Q000295:instrumentation*
Das Elektroretinogramm (ERG) der Maus: normative Werte, optimierte Stimulation und Ableitung.