| Objective To study the relationship between the reduced neural activity level and the intrinsic nitric oxide(NO) level and to find if nitric oxide(NO) play a role in the formation of strabismic amblyopia by observing the density and distribution of nitric oxide synthase(NOS) positive cells in visual cortex (VC) Area 17 of amblyopic cats caused by artificial squint. Methods 12 4-week-old kittens were randomly divided into strabismus and normal groups. The animal modle was obtained by artificially induced esotropia monocularly on 4-week-old kittens and amblyopia was developed in the squint eye which is comfirmed by P-VEP record one month later. The cats were killed by irrigation at the age of 8 weeks and the bilateral visual cortex area 17 was sectioned coronally and the NOS immunocytochemstry staining method was applied accordingly. Observing under the light microscope the changes of distribution and cells density across the visual cortex, compared to that from the nomal cats of identical age. Results VHP records show that the amplitude of wave PI was lower(P<0.05) and the PI latent time was longer(P<0.05) in 8-week-old strabismic cats than those in the normal cats. Compared to the normal cats, the NOS positive cells dencity and the NOS positive fibers are obviously redused in the strabismic amblyopic cats across the 6 layers of the area 17(P<0.05). Conclusions NOS positive cells dencity is redused across the 6 layers of the area 17 which indicates a role NO might play in the formation of strabismic amblyopia in the level of primary visual cortex, probably by its activity-dependent weakening andstrengthening of the presynaptics as both a retrograde and an antegrade messenger. In addition,the reduction of NO level may accout for the deficieny of the squint eye in signal detection and coding process which sheds light on the so called spatiotemporal interpolation hypotheses.Xu Li (Ophthalmology) Directed by Hu Cong...
|
PDF Full Text Request