| Objective To investigate the effects of monocular deprivation(Monocular deprivation, MD)mice on the expression of N-methy-D-aspartate(N-methy-D-aspartate, NMDA)receptor subunits in the V1 B area of visual cortex during the critical period of visual development after intraperitoneal injection of NR2 B receptor blocking agent, and to explore the function of NR2 A, NR2 B in visual development and synaptic plasticity,further providing theoretical evidences for amblyopia.Methods1.20 3- to 4-week-old C57BL/6 mice were reared in normal light/dark 12 hr cycles,They were randomly divided into four groups, 5 mice in each group. The first group give Ifenprodil by intraperitoneal injection( a dose of 10 mg / kg), the second group on monocular deprivated for 6 days, the third group have both Ifenprodil and Monocular deprivation. Monocular deprivation was performed by right eyelid suture in postnatal 24 days. All of mice were reared in same environment.Anesthesia death decapitated.2.HE and immunofluoresence staining,Quantitative Real-time PCR were used to detect the expression of NMDA receptor subunits NR2 A, NR2 B in the V1 B area of visual cortex. 3.Statistical Methods: All statistics were expressed as mean ± standard deviation; side differences in the cortex of data using paired t test about the same group of mice; two-way ANOVA were using in different groups, P <0.05 was significant after statistication.Results1.HE staining, All of mice visual cortex neurons on both sides of the structure is clear, the neurons lined in order in every layer.There was no obviously abnormality in visual cortex of 3 experimental groups compared with normal group.2.Immunofluorescence histochemistry stain: Receptor-positive cells were mainly located in the cell membrane and cytoplasm.The expression of four groups of mice visual cortex NR2 A, NR2B: No significant difference in normal group ipsilateral and contralater visual cortex(P = 0.834, P = 0.727; P = 0.837, P = 0.624). NR2 A expression was lower in MD group(t =-2.485, P <0.05), NR2 B was higher(t =4.404, P <0.05).The expression of NR2 A was lower in MD + Ifenprodil group of ipsilateral visual cortex(t=-3.596, P<0.05), no significant difference NR2 B expression between both of visual cortex. The expression of NR2 A, NR2 B for four groups of mice contralater visual cortex : Compared with the N group, The expression of NR2 A in MD group and MD + Ifenprodil group was lower(t=-0.315,P<0.05;t=-3.397,P<0.05). Compared with Ifenprodil group, NR2 A expression was lower in MD+Ifenprodil group(t = 4.716, P <0.05), The expression of NR2 B in MD group a was higher than normal group(t=-6.812,P<0.05), compare with normal group, the expression of NR2 B in Ifenprodil group and MD + Ifenprodil group was lower(t= 5.633, P <0.05; t = 5.409, P < 0.05).The expression of NR2 A, NR2 B for four groups of mice ipsilateral visual cortex :Compared with N group, Ifenprodil group, MD group compared with the MD +Ifenprodil group N group the expression of NR2 A was higher(t=-4.168, P <0.05; t=-2.619, P <0.05; t =-3.397, P <0.05). NR2 B expression MD group was lower(t=4.381, P <0.05), the expression of NR2 B in Ifenprodil group and MD +Ifenprodil group was lower(t = 5.316, P <0.05; t = 6.366, P < 0.05).Quantitative Real-time PCR: The expression of four groups of mice visual cortex NR2 A m RNA, NR2 B m RNA.:The expression of the NR2 A m RNA、NR2B m RNA was no significant different in N group Ifenprodil group(N group P =0.975,P = 0.884; Ifenprodil group P =0.859, P =0.906). MD group NR2 A m RNA expression was lower(t =-9.201, P <0.05), the expression of NR2 B m RNA was higher in contralater visual cortex(t = 9.876, P <0.05). The expression of NR2 A m RNA in MD was lower in contralater visual cortex(t =-7.436, P <0.05), NR2 B m RNA expression was no significant difference. The expression of four groups NR2 A m RNA, NR2 B m RNA in contralater visual cortex: Compared with N group,Ifenprodil group NR2 A m RNA expression was higher(t =-4.352, P <0.05), MD group and MD + Ifenprodil group was lower(t = 8.861, P <0.05); Compared to the normal group, the expressionof NR2 B m RNA in MD group was higher, the expression of NR2 B m RNA in Ifenprodil group and MD + Ifenprodil group was lower in contralater visual cortex(t = 4.379, P <0.05; t = 5.445,P <0.05), The expression of NR2 Am RNA, NR2 Bm RNA for four groups of mice ipsilateral visualcortex :Compare to normal group, the expression of NR2 A m RNA was higher in Ifenprodil group, MD group and MD+Ifenprodil group(t=-2.746,P<0.05;t=-3.932, P < 0.05; t=-3.511, P < 0.05), the expression of NR2 Bm RN was lower(t=-3.932, P < 0.05),compare to normal group the expression of NR2 B m RNA was lower(t=4.379,P<0.05;t=5.445,P<0.05).3. Conclusions1. The expression of receptor subunits dependent on in the normal development of the visual cortex is dependent on experience: the expression of NR2 A is higher,the expression of NR2 B is lower. The expression of NR2 A is lower, NR2 B is higher in monocular deprivation mice.2. Intraperitoneal injection of Ifenprodil, can be through blood-brain barrier,selective effect on visual cortex NMDA receptor NR2 B subunit.3. NMDA receptor blockers can inhibit the expression of NR2 B subunit, to explore the mechanism of monocular deprivation amblyopia and to find a breakthrough in drug treatment. |
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