Abstract
Purpose: :
To evaluate the effect of transcranial magnetic stimulation (TMS) on retinal function in Royal College of Surgeons (RCS) rats.
Methods: :
Four weeks old RCS rats underwent electroretinogram (ERG) before TMS treatment and followed weekly for 7 weeks (11 weeks follow-up). A total of 24 rats received 6 or 12 sessions (1-2 or 1-4 weeks, respectively) of either real (active, n=8 / group) or sham (placebo, n=8 / group) TMS over the right eye. Evaluation of effects was performed using ERG in scotopic and photopic conditions every week in each eye.
Results: :
Two weeks of treatment (6 sessions) indicated a delayed and transient improvement in the scotopic maximal negative ERG responses in each eye (24% and 102% of change improvement compared to placebo in the right and left eye respectively, 4 and 5 weeks after treatment p<0.05). Extending the treatment to four weeks (12 sessions) showed greater improvements in the negative ERG responses as well as in the maximal scotopic b-waves ERG amplitude responses. Three to five weeks after treatment the average maximal scotopic b-wave amplitude responses showed significant increase (P<0.05) of up to 637% and 363% of change relative to placebo in the right and left eyes respectively. The single flash photopic b- wave amplitude responses showed increase of 207% and 185% of change compare to placebo in the right and left eyes respectively.
Conclusions: :
Using a new application for TMS we showed for the first time that TMS treatment induces delayed improvement of the retinal function in animal model of retinal degeneration. These results suggest that repeated treatment with TMS might induce neural plasticity in the neuroretinal tissue.
Keywords: neuroprotection • plasticity • retinal degenerations: hereditary