Binocular Form Deprivation Research Articles

The postnatal development of perineuronal net, Nogo receptor and the effect of fluoxetine on remodeling it in the visual cortex of rats

Objective: To investigate the postnatal development of perineuronal net (PNN), Nogo receptor (Nogo R) in visual development and the effect of fluoxetine(Flx) on remodeling it in the visual cortex of adult rats. Methods: Experimental study. (1) Wistar rats were divided into postnatal weeks (PW)1,PW3,PW5,PW7,PW9 group (8 rats in each group) according to the age of PW. The changes of PNN and Nogo R were observed in the visual cortex of each group. (2) The adult rats (10 weeks after birth) were randomized into Flx 0W, Flx 2W, Flx 4W, Flx 6W and Flx 8W group (8 rats in each group) according to Flx administrational weeks. The influence of Flx on the expression of PNN and Nogo receptor in the visual cortex was detected by immunofluorescence and western blots. (3) The adult rats were randomized into Cont (negative control), Flx, binocular form deprivation(BFD,positive control) and BFD+Flx group (8 rats in each group). Flx group accepted oral administration at the dosage of 0.2 mg/ml once per day for 4 weeks. The eyelids were binocularly sutured for 2 weeks to form the BFD group, and the combination of Flx administration and BFD was performed in the BFD+Flx group.No intervention was conducted in the control group (Cont group). Immunofluorescence was used to observe the expression pattern of PNN staining by biotinylated wisteria floribunda lectin (WFA). The expression of Nogo R in the visual cortex was detected by immunofluorescence and Western blots. The expression of PNN and Nogo R were examined in each group. And t test, analysis of variance and rank sum test were employed for inter-group comparison based on the homogeneity of variance. Bonferroni method was used for multiple comparison and simple linear regression analysis was used for the trend. Results: (1) The expression of PNN (standardized b=0.97, P=0.005) and Nogo R (standardized b=0.96, P=0.010) increased during the postnatal development and the Nogo R reached the matured level at PW7 (PW7 vs. PW9, 131.83±3.78 vs. 135.11±3.92, Z=1.93, P=0.062). (2) Flx significantly decreased PNN in the visual cortex of adult rats. The density of PNN-positive cells in the visual cortex of healthy adult rats fed with Flx for 4 weeks was (86.22±7.68)/mm(2), which was similar to that of 3 weeks old rats [(84.21±6.68)/mm(2), t=2.08, P=0.073]. The expression of PNN (standardized b=-0.88, P=0.040) and it's receptor Nogo R (standardized b=-0.90, P=0.007) decreased with prolongation of Flx use. (3) The expression of Nogo R (t=13.42,11.47, 18.13; P=0.012, 0.013, 0.001; Flx, BFD and BFD+Flx group vs. Cont group) and the density of PNN (t=10.09, 7.64, 13.01; P=0.007, 0.011, 0.001; Flx, BFD and BFD+Flx group vs. Cont group) could be modulated by Flx and BFD after the critical period. There are no differences in BFD and Flx group on Nogo R changes (t=2.41, P=0.153). The expression of Nogo R protein was also different among the 4 groups (H=5.69, P=0.041). The effect of Flx combined with BFD was better than the Flx or BFD alone (Flx vs. BFD+Flx, Z=4.22, P=0.005; BFD vs. BFD+Flx, Z=3.09, P=0.010). Conclusions: The expression of PNN and Nogo R increase during the postnatal development. Chronic Flx treatment decrease the expression of PNN and Nogo R after the critical period in the visual cortex of adult rats, that is the same as BFD. (Chin J Ophthalmol, 2019, 55:37-45).

Expression of Perineuronal Nets, Parvalbumin and Protein Tyrosine Phosphatase σ in the Rat Visual Cortex During Development and After BFD

Purpose of the Study: Protein tyrosine phosphatase σ (PTPσ) acts as a neuronal receptor for chondroitin sulfate proteoglycans (CSPGs). CSPGs have inhibitory effects on experience-dependent plasticity and usually form lattice-like cell coatings that surround the parvalbumin (PV) interneurons in the visual cortex (VC). We investigated developmental changes and the effect of binocular form deprivation (BFD) on PTPσ, perineuronal nets (PNNs) and their tempo-spatial relationships with PV neurons in the VC.Materials and Methods: Double-immunostaining was used to observe the coexpression pattern of PNNs staining by biotinylated wisteria floribunda lectin (WFA) with PV neurons. The expression of PTPσ in the VC of Long Evans rats was detected by real-time quantitative PCR, immunohistochemistry and western blots. The changes in the number of PV/WFA/PTPσ labeled cells in layer IV of the VC and its proportion of PV neurons were examined during development and after BFD.Results: The expression of PV neurons wrapped by PNNs was increased, particularly in the first half of the critical period, and the ratio for PV neurons reached the highest level (over 75%) at adulthood, indicating that PNNs may play an important role in the maturation of PV neurons during the critical period. BFD decreased the density of PNNs and the percentage of PV neurons with PNNs. This result suggests that the number of PNNs surrounding PV neurons may be experience-dependent. Meanwhile, the CSPG receptor PTPσ was maintained at its lowest level during the critical period and could be modulated by BFD after the critical period. The percentage of PV/WFA/PTPσ-positive cells in PV population increased during development and reached its highest ratio at adulthood, which could also be reversed by BFD.Conclusions: The changes in the coexpression of PNNs, PV and PTPσ provide valuable insights into the connection between CSPGs and PV neurons.

Effect of protein tyrosine phosphatase σ on the reactivation of ocular dominance plasticity in the visual cortex of adult rats

Background Chondroitin sulphate proteoglycans (CSPGs) can cause the termination of ocular dominance plasticity in the visual cortex.Recently,protein tyrosine phosphatase σ (PTPσ) has been identified as a receptor that inhibits CSPGs.However,whether PTPσ and its downstream molecules participate in the reactivation of ocular dominance plasticity in adult visual cortex has not been studied.Objective The present study was to investigate the changes in the expression of the PTPσ,probabilistic neural networks (PNNs),and molecules downstream of PNN,such as N-cadherin/β-catenin,after the reactivation of adult visual cortical plasticity.Methods Fifty-four SPF Long Evans rats were grouped according to different postnatal week (PW) as the PW1 (6 rats),PW3 (6 rats),PW5 (6 rats),PW7 (24 rats),and PW9 (12 rats) groups,and the upper and lower eyelids were sutured in the 12 rats from the PW7 group for 14 days to establish the binocular plasticity reactivation models.Expression of PTPσ and PNNs in the rat visual cortex was detected using immunochemistry,and changes of PTPσ mRNA,N-cadherin mRNA and β-catenin mRNA expression in the rat visual cortex with plasticity reactivation were assessed by real-time fluorescence quantitative PCR (RT Q-PCR).The use of animals followed the Regulations for the Administration of Affairs Concerning Experimental Animals by State Science and Technology Commission.Results The expression level of PTPσ mRNA was significantly higher in the PW9 group than that of the binocular plasticity reactivation models and the PW7 group (t =1.965,3.526,P＜0.01).The staining of the rat visual cortex for PTPσwas localized to the cellular membrane,cytoplasm and axon.Cell densities of the PW9 group in the Ⅱ-Ⅲ layer,Ⅳ layer and Ⅴ-Ⅵ layer of the visual cortex were elevated in the PW9 rats compared with the PW7 rats (t =24.593,23.444,13.556,P＜0.01) and rats from the binocular plasticity reactivation model (t =44.111,43.000,16.556,P＜0.01).Cell densities for PNNs in the Ⅳ and Ⅴ-Ⅵ layers were significantly increased in the PW9 rats in comparison with the PW7 rats (t=1.926,P＜0.01 ;t=1.370,P＜0.05),but the cell density in the Ⅱ-Ⅱ layer has no statistical significance (t=0.889,P＞0.05).However,cell densities for PNNs in the Ⅱ-Ⅲ and Ⅳ layers in the binocular plasticity reactivation models were lower than those of the PW9 rats (t =2.556,4.585,P＜0.01).Compared with PW1 rats,the expression levels of the N-cadherin mRNA in the PW3,PW5,PW7,PW9 rats were lower (t =28.932,28.988,27.083,28.908,P＜0.01),but those in the PW7 rats were enhanced in comparison with the PW3 rats,PW5 rats and PW9 rats (t =1.848,1.904,1.825,P＜0.01).No significant difference was seen in the expression of the N-cadherin mRNA between the PW9 rats and rats from the binocular plasticity reactivation model (t =0.072,P＞0.05).A statistically significant increase was found in the β-catenin mRNA expression in the PW1 rats compared with the PW3,PW5,PW7 and PW9 rats (t =3.918,3.534,2.645,4.652,P＜ 0.0 1),as well as between rats from the binocular plasticity reactivation model and the PW9 rats (t =0.570,P＜0.01).Conclusions PTPr,PNNs and β-catenin are involved in the reactivation of ocular dominance plasticity in the adult visual cortex. Key words: Visual cortex; Protein tyrosine phosphatase σ; Plasticity; Binocular form-deprivation

Binocular form deprivation influences the visual cortex.

α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors are considered to play a crucial role in synaptic plasticity in the developing visual cortex. In this study, we established a rat model of binocular form deprivation by suturing the rat binocular eyelids before eye-opening at postnatal day 14. During development, the decay time of excitatory postsynaptic currents mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors of normal rats became longer after eye-opening; however, the decay time did not change significantly in binocular form deprivation rats. The peak value in the normal group became gradually larger with age, but there was no significant change in the binocular form deprivation group. These findings indicate that binocular form deprivation influences the properties of excitatory postsynaptic currents mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptors in the rat visual cortex around the end of the critical period, indicating that form stimulation is associated with the experience-dependent modification of neuronal synapses in the visual cortex.

The visual cortex plasticity of adult rat after binocular form deprivation by pattern visual evoked potential

Background The visual evoked potential (VEP) is an important functional index to assess visual cortex plasticity.Monocular form deprivation(MD) of rat is a classic model to study visual cortex plasticity change.Utilizing VEP technique record the shift of ocular dominance in adult rats model is of an important significance for explore the treating opportunities of amblyopia.Objective The present study was to observe the pattern VEP changes in different ages of Long-Evens rats and the adult rats after binocular form deprivation.Methods Thirty-six healthy SPF Long-Evens rats were divided into PW3,PW4,PW5,PW6 groups according to the postnatal weeks,and PW7 rats included 36 SPF Long-Evens rats.The left eye lids of the rats were sutured in PW3,PW6 and PW7 rats for 3,5,7 days respectively,and PVEP in both left and right eye were recorded to assess the rat age that visual cortex plasticity ended.Bilateral PVEP were recorded in PW7 rats,and the bilateral eyelids were sutured to establish the bilateral form deprivation models.The right eyes were opened in 7,10,14 days,and the left eyes were opened in the next 3,5,7 days respectively and the PVEPs were recorded again to find the shift of ocular dominance and whether binocular form deprivation induce the visual cortex plasticity in adult rats.Results The P100amplitudes of the left eyes were gradually declined and those of the right eyes were raised from 3 to 7 days after MD of the left eyes in rats of PW3 group in comparison with before MD ( P＜0.01 ).In PW6 groups,no significant changes in P100amplitudes of both the right and left eyes were found in the third day after MD,but significant raise in the right eyes and lowing in the left eyes were seen in the 5 and 7 days after MD in comparison with before MD(P＜0.01 ).No any P100changes in both eyes were found in 3-7 days after MD compared with before MD in PW7 rats (P＞0.05).The C/I ratio (contralateral VEP amplitude to ipsilateral VEP amplitude in occluded eyes) in the rats of PW3,PW4 and PW5 groups were 1.07±0.15,1.16±0.16 and 1.14±0.15 respectively in 3 days after MD,showing the significant lowing in comparison with before MD (2.69±0.45,2.58±0.4,2.62±0.32) (P＜0.01),but those of PW6 and PW7 were unchanged (2.80±0.48 vs 2.90±0.46,2.59 ±0.36 vs 2.90±0.46,P＞0.05 ),indicating the absence of ocular dominance plasticity in the adult rats.In rats of PW7 with binocular form deprivation for 14 days,a significant decrease was observed in the C/I ratio in rats with next MD for 3 days,demonstrating that the visual cortex plasticity was reactivated after 14 days of binocular form deprivation in PW7 rats( 1.33±0.18 vs 2.70±0.45,P＜0.01 ).Conclusions PVEP can be recorded in Long-Evens rats.It is a major index for identifying the shift of ocular dominance in the Long-Evens rats.Binocular form deprivation can reflect the visual cortex plasticity in the adult rats. Key words: Visual evoked potential/pattern stimulate ; Visual cortex; Ocular dominance; Form deprivation

Effects of binocular form deprivation on neuron excitory postsynaptic currents in adult visual cortex

目的 探讨双眼形觉剥夺(FD)对成年大鼠视皮层神经元兴奋性突触传递特性的影响.方法 采用视皮层脑片膜片钳全细胞记录和电流分离技术,分别记录9周龄正常大鼠和7周龄大鼠双眼FD后14d的视皮层神经元膜学特性、突触后电流(PSCs)与NMDA兴奋性突触后电流(EPSCs).结果 双眼FD不改变成年大鼠视皮层神经元的膜学特性和PSCs电学指标.双眼FD对成年大鼠视皮层神经元EPSCs、NMDA-EPSCs的峰值以及NMDA-EPSCs在总EPSCs中所占比例,NMDA-EPSCs的复极化时间无明显影响.结论 双眼FD不影响成年大鼠视皮层神经元兴奋性神经传递功能。

Effects of binocular form deprivation on the properties of gamma-aminobutyric acid currents of rat visual cortical neurons

To investigate the effects of binocular form deprivation on the properties of inhibitory synaptic transmission of rat visual cortical neurons during the critical period of visual development. We recorded the postsynaptic currents in visual cortex slices of normal, binocular form deprived and deprivation-removed rats at postnatal days 14, 21 and 28 with the use of whole-cell patch recording, and recorded gamma-aminobutyric acid currents by adding D, L-2-amino-5-phosphonovalerate (50 micromol/L) and 6-cyano-7-nitroquinoxaline-2,3-dione (20 micromol/L) to artificial cerebrospinal fluid. The electrophysiological properties were also analysed. The decay time and peak value of inhibitory postsynaptic currents of normal rat visual cortical neurons became larger with age (P < 0.05), but not in binocular form deprived group (P > 0.05). The decay time and peak value of inhibitory postsynaptic currents became large in deprivation-removed rats at postnatal days 28 (P < 0.05). The rise time did not change markedly in all groups. With visual development, the synaptic transmission of visual cortical neurons in normal rats is strengthened, but it can be inhibited by binocular form deprivation and recovered by visual input.

Effects of binocular form deprivation on the excitatory post-synaptic currents mediated by N-methyl-D-aspartate receptors in rat visual cortex.

To investigate the effects of binocular form deprivation (BFD) on the excitatory post-synaptic currents (EPSCs) mediated by the N-methyl-D-aspartate (NMDA) receptor (NMDA-EPSCs), and the proportion of NMDA-EPSCs relative to glutamate receptor currents (glutamate-EPSCs) in rat visual cortex. Binocular form deprivation was achieved by suturing the eyelids of Wistar rats at postnatal day (PD) 14, before eye-opening. Visual cortical slices (300 micro m) were prepared from normal and BFD Wistar rats aged PD 14, 21 and 28. Recordings were obtained in slices from layer II to IV using the whole-cell patch-clamp technique. Glutamate-EPSCs were isolated in the presence of bicuculline methiodide (20 micro mol/L) in the bathing medium, and NMDA-EPSCs were isolated with a combination of bicuculline methiodide (20 micro mol/L) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 20 micro mol/L). In addition, D,L-2-amino-5-phosphonovalerate (AP-5, 20 micro mol/L) was applied to study the NMDA-only mediated currents. For each cell, the ratio of peak NMDA to glutamate EPSCs was calculated. During visual development, the decay time constant of NMDA-EPSCs became shorter after eye-opening in normal rats (F = 5.949, P <0.05; PD 28 vs PD 14, P = 0.027), but not in rats with BFD (P > 0.05). The weighted time constant of NMDA-EPSCs in the visual cortex became shorter after the rats' eyes were opened in the normal group (F(2,37) = 4.727, P = 0.015; PD 28 vs PD 14, P = 0.035), but not in the BFD group (P > 0.05). However, the rise time constant and peak value of NMDA-EPSCs showed no significant changes in normal and BFD groups (P > 0.05). The ratio of NMDA-EPSCs to glutamate-EPSCs became gradually smaller with age in the normal rats (F = 4.661, P < 0.05; PD 28 vs PD 14, P = 0.025), but not in the BFD group (P > 0.05). These studies reveal that the proportion of NMDA-EPSCs relative to glutamate-EPSCs and the decay time constant of NMDA-EPSCs are influenced by BFD. These changes may reflect important experience-dependent modifications of neuronal synapses in visual cortex.