Abstract
Purpose: :
To test the contrast detection ability in two mouse models of the Duchenne Muscular Dystrophy (DMD), the mdx and the mdx3CV. And to study the functional alterations caused by the lack or the severe reduction of the DMD gene products (cytoskeletal membrane associated proteins referred as dystrophins) at the first synapse of the retina.
Methods: :
Amongst all the mouse models of DMD, only the mdx3CV strain, which has a mutation causing a severe reduction of all the DMD gene products, presents a reduction of the b–wave amplitude of the electroretinogram (ERG) similar to DMD patients. While the mdx mice which have a lack of the biggest DMD gene product (Dp 427) show no particular reduction of the b–wave amplitude. Based in the fact that mice move mostly the head to follow any visual stimuli (optokinetic nistagmus) a behavioural technique was adapted to estimate the visual acuity to high contrast stimulus, black and white, in movement in both light– and dark–adaptation. The visual stimuli, the optotype, consist in pattern of stripes in black and white in constant horizontal movement adequate to estimate visual acuities from 0,062 c/d to 2,5 c/d.
Results: :
Correlating with the reduction of the b–wave amplitude we have detected that the mdx3cv mice suffer a clear impairment in the high contrast perception in both, dark and light adaptation (p 0,05), the bl10 strain.
Conclusions: :
1) The lost of just the Dp427 (mdx mice) is not enough to disrupt the signal transmission at the first synapse of the retina while the severe reduction of all types of the DMD gene products (mdx3CV mice) disturbs the signal transmission, affecting the message. 2) In contrast to DMD patients the ERG perturbation results in a clear impairment of the visual perception.
Keywords: retina • perception • electroretinography: non-clinical