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A. L. Reynolds, P. F. Kenna, G. J. Farrar, P. Humphries; Strain-Specific Effect of an Increase in Body Temperature on the Electroretinogram. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1298. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Previously it has been shown that environmental variables, such as a decrease in core body temperature have a profound effect on the electroretinogram (ERG). Since handling-induced stress is known to cause an increase in core body temperature, we wanted to find out whether such an increase in core body temperature had an effect on the murine ERG.
Wild type mice from C57BL/6JOlaHsd (C57; n = 5) and 129S2/SvHsd (129; n = 5) strains were used. Animals were dark adapted overnight, anaesthetised using ketamine and xylazine and serial ERGs were performed on each individual at 37°C, 38.5°C, 39.5°C, 40.5°C and 41.5°C every 48 hours. An additional ERG was performed at 37°C. Results were analysed in Datadesk using a paired 2-sample t-test.
A general trend was seen in both C57 and 129 strains as the temperature increased, with ERG timings becoming faster and amplitudes becoming higher. However, an increase in temperature had a greater effect on the 129 compared with the C57 strain. In 129 mice, dark-adapted timings recorded at 41.5°C were 80% of those recorded at 37°C whereas in C57 mice timings recorded at 41.5°C were 86% of those recorded at 37°C. Dark-adapted amplitudes recorded at 41.5°C in 129 mice were 170% of those recorded at 37°C (increase of 35µV/°C), whereas in C57 mice the maximum dark-adapted amplitude was 130% of that recorded at 37°C, with a large difference in amplitude between 37°C and 38.5°C (increase of 5µV/°C above 38.5°C). ERGs re-recorded at 37°C showed that the increase in temperature had not had a damaging effect on retinal function.
A small increase in core body temperature to 38.5°C has a significant difference on timing and amplitude of the ERG in both C57 and 129 mouse strains. The effect on ERG is strain-dependent, with 129 mice showing more severe effects when compared to C57 mice. Increasing core body temperature to 41.5°C does not have a damaging effect on retinal function.
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