Effect Of NGF On The Numberal Density And Morphology Of Positive Neurons Of NNOS In Visual Central System In Monocularly Deprived Rats

ObjectiveTo study the effect of nerve growth factor (NGF) on thenumberal density and morphology of positive neurons ofneuronal nitric oxide synthase (nNOS) in visual central systemin monocularly deprived rats in critical period, and providebasic referent evidences to preventing and treating deprivedamblyopia.Methods1.SD male rats (n=64) of postnatal day 14 were randomlydevided into 8 groups. Rats were deprived in left eyes atpostnatal day 14, immediately before eye open, by means ofeyelid suture with ether anesthesia. 6 rats were normal as N1group, 6 rats were monocularly deprived as MD1 group, 10 ratswere monocular deprived combined with intraventricularinjection with NGF as (MD+NGF)1 group and another 10 ratswith normal saline(NS) as (MD+NS)1 group as control. Theinfusion canula in right ventricule was performed at postnatalday 14, Injections (2ul) were given every day for 2 weeks. Thenthe rats of the four groups were killed at postnatal day 28. Thesame devision was done in N2, MD2, (MD+NGF)2, (MD+NS)2.Monocular deprivation lasted for 4 weeks. The infusion canulain right ventricule was performed at postnatal day 28, Injections(2ul) were given every day for 2 weeks. These four groups ratswere killed at postnatal day 42.2.Changes in numberal density and morphology of positiveneurons of nNOS in area 17 and dLGN in N1, MD1,(MD+NS)1, (MD+NGF)1, N2, MD2, (MD+NS)2 and(MD+NGF)2 were analyzed with immunocytochemestry, SABCtechnique and Computer Image Analysis System.3.All data were analyzed by one-way ANOVA with SPSS12.0.Results1.The positive neurons of nNOS appeared brown colour inlayer Ⅱ～Ⅵof visual cortex area 17 in N1 and (MD+NGF)1.The numberal density of nNOS neurons were more in the Ⅱ/Ⅲand Ⅴ, Ⅵlayers and fewer in the Ⅳlayer. Monoculardeprivation caused striking changes in the numberal density,body area and total length of dendrites of nNOS positiveneurons in MD1 and (MD+NS)1. There was no differencebetween N1 and (MD+NGF)1, and no difference between MD1and (MD+NS)1 too. But the former two groups and the lattertwo by comparation had significant difference. The distributionand morphology of positive neurons of nNOS in 42-day-old ratswas similar to those in 28-day-old rats. But the numberaldensity, cell body area and total length of dendrites of nNOSpositive neurons decreased in 42-day-old rats. And the results ofN2, MD2, (MD+NS)2 and (MD+NGF)2 were same in thenumberal density and total length of dendrites. No effect couldbe found providing rats with NGF at postnatal day 28. The cellbody area of N2 was bigger than that in other groups.2. The neurons of N1 were light brown in dLGN. Thenumberal density in (MD+NGF) 1 was similar to that in N1.There was marked decrease in numberal density in MD1. Thenumberal density in (MD+NS)1 and MD1 by comparision hadno significant difference. Moreover, the numberal density in N2was higher than that in other groups. No difference were foundamong MD2, (MD+NS)2 and (MD+NGF)2 .Conclusions1.The numberal density, cell body area and total length ofdendrites of nNOS positive neurons decreased in area 17 and thenumberal density in dLGN also decreased in rats monocularlydeprived at postnatal day 14.2. Providing NGF at postnatal day 14, NGF was effective inpreventing the effect of monocular deprivation in rats'visualcortex and dLGN. But no effect could be found providing ratswith NGF at postnatal day 28.3. There was no difference between MD1 and (MD+NS)1,and no difference between MD2 and (MD+NS)2 too. Theevidence showed that intraventricular injection had no effect onthe results. NS wasn't effective on deprived amblyopia,...