Roles Of Vasoactive Intestinal Peptide In The Normal Visual Development And Strabismic Amblyopia And Effects Of It On Strabismic Amblyopic Kittens

ObjectiveTo study the expression changes of vasoactive intestinal peptide (VIP) in visual cortex of the normal and the strabismic amblyopic kittens during development. The possible relation between VIP and plasticity of visual system was discussed. Meantime, to study the treatment effects of vasoactive intestinal peptide (VIP) on the strabismic amblyopic kittens. A possible mechanism was discussed. These studies offer a basis of reference in preventing and treating amblyopia in children.Methods1. Sixteen normal kittens (4 weeks old) were divided into two groups randomly. Eight kittens were deduced strabismus by amputating external rectus muscles of right eyes in 4 weeks old. 2 normal and 2 strabismic kittens were perfused in every three weeks. Changes in number and optical density of immunopositive neurons of the expression of VIP in the visual cortex area 17 were analyzed with the technique of in situ hybridization. Transmission electron microscope was used to observe the ultrastructure of the visual cortex neurons. 2. Sixteen normal kittens (4 weeks old) were divided into four groups randomly. Twelve kittens were deduced strabismus by cutting external rectus muscles of right eyes in 4 weeks old. Four of them (VIP intervened groups) were delivered intranasal administration of 10μg VIP/40μl (containing 10%sefsol and 40%isopropanol) and other four of them (sefsol intervened contrast groups) were administrated 10%sefsol and 40% isopropanol. All of the kittens were perfused in 12 weeks old. Changes in number and optical density of immunopositive neurons of the expression of VIP in the visual cortex area 17 were analyzed with the technique of in situ hybridization.Result1,Roles of vasoactive intestinal peptide in the normal visual development and strabismic amblyopia:1.1 The number and optical density of VIP immunoreactive cells in normal kittens was higher than in amblyopia kittens at the same age (p<0.05).1.2 The ultrastructure of cell was changed.2,Effects of vasoactive intestinal peptide on strabismic amblyopic kittens: The depth of the P₁₀₀ in the kittens of the VIP intervened groups are higher than it of the sefsol intervened contrast groups and strabismic non-intervened groups, and the P₁₀₀ latency were shorten in 12 weeks old. The number and optical density of VIP-immunopossitive neurons were increased.Conclusion1,The studies indicated that the abnormal visual experience induced the less expression of VIP mRNA and the function of neurons descended in the visualcortex area 17. Which lead to amblyopia. So VIP may make an important rolein visual development.2. The visual function of the strabismic amblyopic kittens have improved,after intranasal administration of VIP.3,The VIP has the therapic effects on strabismic amblyopic kittens.