Abstract
Purpose:
Toll-like receptors, key mediators in the inflammatory response, have been recognized as modulators of neuronal development and survival. The objective of this study is to assess the role of TLR4 in the structure and function of the mouse retina.
Methods:
Retinal responsiveness and visual acuity were evaluated by electroretinography and optomotor test, respectively, in TLR4-/- knockout and wild type C57BL/6J mice at P20, P30 and P60. Retinal structure was also assessed at P30 in both animal strains by immunohistochemical techniques and confocal microscopy.
Results:
TLR4-/- mice showed reduced retinal responsiveness, as compared to wild type animals. The scotopic a- and b-waves were significantly lower in TLR4-defective mice than in wild type animals at all ages tested (P20, P30 and P60) (ANOVA, p<0.05). Visual acuity was also lower in TLR4-/- compared to C57BL/6J mice, with significant differences at P60 (ANOVA, p<0.05). Vertical retinal sections from P30 TLR4-/- mice showed lower density of bipolar cells and less synaptic contacts between photoreceptors and bipolar cells (ANOVA, p <0.05 in both cases) than in the wild type.
Conclusions:
Absence of the innate immune receptor TLR4 alters the structure and impairs the function in the mouse retina.