Purpose:
To investigate the functional changes in the inner retina after intraorbital optic nerve transection (IONT) in adult mice.
Methods:
In adult female albino (Balb/c) and pigmented (C57BL/6N) mice (25-35g) the left optic nerve was transected intraorbitally to induce retinal ganglion cell (RGC) loss. Electroretinographic (ERG) responses were recorded simultaneously from both eyes and compared each other prior to and at different survival intervals ranging from 2 to 12 weeks after IONT. White light stimuli of intensities ranging from 10-6 to 10-4 cd·s·m-2 were used to record the scotopic threshold response (STR) and stimulus light intensities ranging from 10-4 to 102 cd·s·m-2 were used to analyze the a- and b-wave amplitudes.
Results:
For albino mice, 2 weeks after IONT the mean amplitude of both STR components was decreased significantly to approximately 40% of the values registered for the non-operated eye (t-test; p<0.05). At 12 weeks after IONT, the pSTR and nSTR remained significantly reduced to approximately 45% and 70% respectively. The a- and b-waves amplitudes showed a small reduction to approximately 85% until 12 weeks (t-test; p<0.05). For pigmented mice, 2 weeks after IONT the mean amplitude of pSTR and nSTR was decreased significantly to approximately 30% and 65% respectively (t-test; p<0.05). At 12 weeks after IONT, both STR components were reduced to approximately 45%. The a- and b-waves amplitudes showed a small reduction to approximately 80% until 12 weeks (t-test; p<0.05). The implicit time of STR is reduced respect to the contralateral eye for both strains for all studied times after IONT (Mann-Whitney; p<0.05).
Conclusions:
IONT, which is known to induce rapid and massive degeneration of RGCs, is associated with selective changes in the STR components of the mice ERG. STR could be a useful functional parameter to monitor RGC survival in adult mice.
Keywords: electroretinography: non-clinical • ganglion cells • optic nerve