Limits...
Exendin-4 protects retinal cells from early diabetes in Goto-Kakizaki rats by increasing the Bcl-2/Bax and Bcl-xL/Bax ratios and reducing reactive gliosis.

Fan Y, Liu K, Wang Q, Ruan Y, Zhang Y, Ye W - Mol. Vis. (2014)

Bottom Line: It also downregulated the expression of glial fibrillary acidic protein and reduced retinal reactive gliosis.Similar results were found in primary rat Müller cells under high glucose culture in vitro.E4 may protect retinal cells from diabetic attacks by activating GLP-1R, decreasing retinal cell apoptosis, and reducing retinal reactive gliosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Huashan Hospital Affiliated to Fudan University, Shanghai, China.

ABSTRACT

Purpose: Exendin-4 (E4), a long-acting agonist of the hormone glucagon-like peptide 1 receptor (GLP-1R), is administered to treat type II diabetes in the clinical setting and also shows a neuroprotective effect. Our previous studies demonstrated its protective effect in early experimental diabetic retinopathy (DR), but the molecular and cellular mechanisms are largely unknown. This study aimed to investigate the protective mechanism of a GLP-1R agonist E4 against early DR in Goto-Kakizaki (GK) rats.

Methods: Diabetic GK rats and control animals were randomly assigned to receive E4 or vehicle by intravitreal injection. The retinal function and retinal cell counts were evaluated using an electroretinogram and light microscopy. The expressions of retinal GLP-1R, mitochondria-dependent apoptosis-associated genes, reactive gliosis markers, and endoplasmic reticulum stress-related pathway genes were studied by western blotting and immunohistochemistry in vivo and in vitro.

Results: E4 significantly prevented the reduction of the b-wave and oscillatory potential amplitudes and retinal cell loss and maintained the Bcl-2/Bax and Bcl-xL/Bax ratio balances in GK rats. It also downregulated the expression of glial fibrillary acidic protein and reduced retinal reactive gliosis. Similar results were found in primary rat Müller cells under high glucose culture in vitro.

Conclusions: E4 may protect retinal cells from diabetic attacks by activating GLP-1R, decreasing retinal cell apoptosis, and reducing retinal reactive gliosis. Thus, E4 treatment may be a novel approach for early DR.

Show MeSH

Related in: MedlinePlus

Reduction in the retinal reactive gliosis by E4 treatment in diabetic GK rats in vivo and in vitro. Western blot analysis of retinal GFAP (A) and vimentin (B) expression in three groups (one-way ANOVA followed by Bonferroni’s test: GFAP, G+NS versus G +Ε4, t=6.501, p<0.001, n=4). C: Immunohistochemistry of retinal GFAP in three groups. D: Reduction of GFAP expression in primary Müller cells (RMCs) from Wistar rat at different time points (24 h, 48 h, and 72 h) by E4 treatment under high glucose culture (20 mM; one-way ANOVA followed by Bonferroni’s test: control [D-glucose, 5.6 mM] versus control [D-glucose, 20 mM], t=11.5, p<0.001; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 24 h E4 treatment], t=3.396, p=0.040; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 48 h E4 treatment], t=3.957, p=0.013; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 72 h E4 treatment], t=5.157, p=0.001;n=4. (*: p<0.05, **: p<0.01, #: p<0.001). GK rat: Goto-Kakizaki rat; E4: Exendin-4; GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; ONL, outer nuclear layer. The scale bar represents 100 μm. Control: Wistar rats treated with sham injection (normal saline); G+NS: GK rats treated with sham injection (normal saline); G+E4: GK rats treated with E4 intravitreal injection. Data are expressed as the means ± SEM. One-way ANOVA followed by Bonferroni’s test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4225140&req=5

f6: Reduction in the retinal reactive gliosis by E4 treatment in diabetic GK rats in vivo and in vitro. Western blot analysis of retinal GFAP (A) and vimentin (B) expression in three groups (one-way ANOVA followed by Bonferroni’s test: GFAP, G+NS versus G +Ε4, t=6.501, p<0.001, n=4). C: Immunohistochemistry of retinal GFAP in three groups. D: Reduction of GFAP expression in primary Müller cells (RMCs) from Wistar rat at different time points (24 h, 48 h, and 72 h) by E4 treatment under high glucose culture (20 mM; one-way ANOVA followed by Bonferroni’s test: control [D-glucose, 5.6 mM] versus control [D-glucose, 20 mM], t=11.5, p<0.001; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 24 h E4 treatment], t=3.396, p=0.040; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 48 h E4 treatment], t=3.957, p=0.013; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 72 h E4 treatment], t=5.157, p=0.001;n=4. (*: p<0.05, **: p<0.01, #: p<0.001). GK rat: Goto-Kakizaki rat; E4: Exendin-4; GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; ONL, outer nuclear layer. The scale bar represents 100 μm. Control: Wistar rats treated with sham injection (normal saline); G+NS: GK rats treated with sham injection (normal saline); G+E4: GK rats treated with E4 intravitreal injection. Data are expressed as the means ± SEM. One-way ANOVA followed by Bonferroni’s test.

Mentions: The expression of GFAP in the retinas of 16-week-old GK rats was dramatically upregulated to 72.9-fold the level of the Wistar control (Figure 6A). The GFAP expression of the E4-treated group was significantly reduced to 73.7% of the GK control level (Figure 6A, p<0.001). Similarly, the vimentin expression was upregulated to 116.6% of Wistar control level in the GK group and reduced to 87.3% of the GK control level in the E4-treated group, although the three groups did not significantly differ (Figure 6B; p>0.05). In addition, the retinal immunostaining changes in GFAP among the three groups were consistent with the western blotting analysis (Figure 6C). In vitro, the GFAP expression level in RMCs after 72 h of high glucose treatment was upregulated (5.2-fold of the normal control) and downregulated (2.8-fold of the normal control) after 72 h of E4 treatment (Figure 6D).


Exendin-4 protects retinal cells from early diabetes in Goto-Kakizaki rats by increasing the Bcl-2/Bax and Bcl-xL/Bax ratios and reducing reactive gliosis.

Fan Y, Liu K, Wang Q, Ruan Y, Zhang Y, Ye W - Mol. Vis. (2014)

Reduction in the retinal reactive gliosis by E4 treatment in diabetic GK rats in vivo and in vitro. Western blot analysis of retinal GFAP (A) and vimentin (B) expression in three groups (one-way ANOVA followed by Bonferroni’s test: GFAP, G+NS versus G +Ε4, t=6.501, p<0.001, n=4). C: Immunohistochemistry of retinal GFAP in three groups. D: Reduction of GFAP expression in primary Müller cells (RMCs) from Wistar rat at different time points (24 h, 48 h, and 72 h) by E4 treatment under high glucose culture (20 mM; one-way ANOVA followed by Bonferroni’s test: control [D-glucose, 5.6 mM] versus control [D-glucose, 20 mM], t=11.5, p<0.001; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 24 h E4 treatment], t=3.396, p=0.040; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 48 h E4 treatment], t=3.957, p=0.013; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 72 h E4 treatment], t=5.157, p=0.001;n=4. (*: p<0.05, **: p<0.01, #: p<0.001). GK rat: Goto-Kakizaki rat; E4: Exendin-4; GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; ONL, outer nuclear layer. The scale bar represents 100 μm. Control: Wistar rats treated with sham injection (normal saline); G+NS: GK rats treated with sham injection (normal saline); G+E4: GK rats treated with E4 intravitreal injection. Data are expressed as the means ± SEM. One-way ANOVA followed by Bonferroni’s test.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4225140&req=5

f6: Reduction in the retinal reactive gliosis by E4 treatment in diabetic GK rats in vivo and in vitro. Western blot analysis of retinal GFAP (A) and vimentin (B) expression in three groups (one-way ANOVA followed by Bonferroni’s test: GFAP, G+NS versus G +Ε4, t=6.501, p<0.001, n=4). C: Immunohistochemistry of retinal GFAP in three groups. D: Reduction of GFAP expression in primary Müller cells (RMCs) from Wistar rat at different time points (24 h, 48 h, and 72 h) by E4 treatment under high glucose culture (20 mM; one-way ANOVA followed by Bonferroni’s test: control [D-glucose, 5.6 mM] versus control [D-glucose, 20 mM], t=11.5, p<0.001; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 24 h E4 treatment], t=3.396, p=0.040; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 48 h E4 treatment], t=3.957, p=0.013; control [D-glucose, 20 mM] versus E4 treatment [20 mM D-glucose + 72 h E4 treatment], t=5.157, p=0.001;n=4. (*: p<0.05, **: p<0.01, #: p<0.001). GK rat: Goto-Kakizaki rat; E4: Exendin-4; GCL, ganglion cell layer; IPL, inner plexiform layer; INL, inner nuclear layer; ONL, outer nuclear layer. The scale bar represents 100 μm. Control: Wistar rats treated with sham injection (normal saline); G+NS: GK rats treated with sham injection (normal saline); G+E4: GK rats treated with E4 intravitreal injection. Data are expressed as the means ± SEM. One-way ANOVA followed by Bonferroni’s test.
Mentions: The expression of GFAP in the retinas of 16-week-old GK rats was dramatically upregulated to 72.9-fold the level of the Wistar control (Figure 6A). The GFAP expression of the E4-treated group was significantly reduced to 73.7% of the GK control level (Figure 6A, p<0.001). Similarly, the vimentin expression was upregulated to 116.6% of Wistar control level in the GK group and reduced to 87.3% of the GK control level in the E4-treated group, although the three groups did not significantly differ (Figure 6B; p>0.05). In addition, the retinal immunostaining changes in GFAP among the three groups were consistent with the western blotting analysis (Figure 6C). In vitro, the GFAP expression level in RMCs after 72 h of high glucose treatment was upregulated (5.2-fold of the normal control) and downregulated (2.8-fold of the normal control) after 72 h of E4 treatment (Figure 6D).

Bottom Line: It also downregulated the expression of glial fibrillary acidic protein and reduced retinal reactive gliosis.Similar results were found in primary rat Müller cells under high glucose culture in vitro.E4 may protect retinal cells from diabetic attacks by activating GLP-1R, decreasing retinal cell apoptosis, and reducing retinal reactive gliosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Ophthalmology, Huashan Hospital Affiliated to Fudan University, Shanghai, China.

ABSTRACT

Purpose: Exendin-4 (E4), a long-acting agonist of the hormone glucagon-like peptide 1 receptor (GLP-1R), is administered to treat type II diabetes in the clinical setting and also shows a neuroprotective effect. Our previous studies demonstrated its protective effect in early experimental diabetic retinopathy (DR), but the molecular and cellular mechanisms are largely unknown. This study aimed to investigate the protective mechanism of a GLP-1R agonist E4 against early DR in Goto-Kakizaki (GK) rats.

Methods: Diabetic GK rats and control animals were randomly assigned to receive E4 or vehicle by intravitreal injection. The retinal function and retinal cell counts were evaluated using an electroretinogram and light microscopy. The expressions of retinal GLP-1R, mitochondria-dependent apoptosis-associated genes, reactive gliosis markers, and endoplasmic reticulum stress-related pathway genes were studied by western blotting and immunohistochemistry in vivo and in vitro.

Results: E4 significantly prevented the reduction of the b-wave and oscillatory potential amplitudes and retinal cell loss and maintained the Bcl-2/Bax and Bcl-xL/Bax ratio balances in GK rats. It also downregulated the expression of glial fibrillary acidic protein and reduced retinal reactive gliosis. Similar results were found in primary rat Müller cells under high glucose culture in vitro.

Conclusions: E4 may protect retinal cells from diabetic attacks by activating GLP-1R, decreasing retinal cell apoptosis, and reducing retinal reactive gliosis. Thus, E4 treatment may be a novel approach for early DR.

Show MeSH
Related in: MedlinePlus