Anti-apoptosis and anti-inflammation effects and mechanism of berberine on high-concentration glucose induced rat retinal Müller cells

Objective

To investigate the effects of berberine on Sprague Dawley (SD) rat retinal Müller cells cultured by high concentration glucose.

Methods

The cultured SD rat retinal Müller cells were divided into normal-glucose group, high-glucose group, high-glucose+ 10 μmol/L berberine group and high-glucose+ 25 μmol/L berberine group, and the cells were cultured in 5 mmol/L glucose, 25 mmol/L glucose, 25 mmol/L glucose+ 10 μmol/L berberine, and 25 mmol/L glucose+ 25 μmol/L berberine, respectively.After 72 hours cultured, cell apoptosis rate was detected by flow cytometry; the expressions levels of tumor necrosis factor-α (TNF-α), interleukin-8 (IL-8) and cyclooxygenase-2 (COX-2) in the culture supernatant were detected by enzyme linked immunosorbent assay (ELISA); the L-glutamate-L-aspartate transporter (GLAST) and the related protein expression levels were detected by real-time fluorescence quantitative PCR; the expressions levels of GLAST, protein phosphatase magnesium-dependent 1A (PPM1A), nuclear factor-κB (NF-κB) and cleaved caspase-3 in the cytoplasm, and the expression level of NF-κB protein in the nucleus were detected by Western blot.

Results

The cell apoptosis rate was (1.37±0.21)%, (17.67±1.17)%, (10.60±0.17)% and (5.57±0.35)% in the normal-glucose group, high-glucose group, high-glucose+ 10 μmol/L berberine group and high-glucose+ 25 μmol/L berberine group, respectively, and the overall comparative difference was statistically significant (F=375.97, P<0.01). The cell apoptosis rates in the high-glucose group was increased in comparison with those in the normal-glucose group (P<0.01). The cell apoptosis rates in the high-glucose+ 10 μmol/L berberine group and high-glucose+ 25 μmol/L berberine group were significantly reduced in comparison with that in the high-glucose group (both at P<0.01). And the cell apoptosis rate in the high-glucose+ 25 μmol/L berberine group was lower than that in the high-glucose+ 10 μmol/L berberine group (P<0.01). ELISA results revealed that the overall comparative differences of the concentrations of TNF-α, IL-8 and COX-2 among the four groups were statistically significant (F=28.36, 35.88, 41.59; all at P<0.01). The concentrations of TNF-α, IL-8 and COX-2 in the high-glucose group were significantly higher than those in the normal-glucose group (P<0.01). Compared with the high-glucose group, the concentrations of TNF-α and COX-2 were significantly decreased in the high-glucose+ 10 μmol/L berberine group and high-glucose+ 25 μmol/L berberine group (both at P<0.05). The concentrations of TNF-α and IL-8 in the high-glucose+ 25 μmol/L berberine group were lower than those in the high-glucose+ 10 μmol/L berberine group (both at P<0.05). Real-time fluorescence quantitative PCR showed that the relative expression levels of GLAST mRNA in Müller cells among the four groups were statistically significant (F=268.60, P<0.01). Compared with the normal-glucose group, the relative expression level of GLAST mRNA was significantly decreased in the high-glucose group (P<0.01). In the high-glucose+ 10 μmol/L berberine group and high-glucose+ 25 μmol/L berberine group, the relative expression level of GLAST mRNA was significantly elevated compared with the high-glucose group (both at P<0.05). Western blot analysis results showed that the overall comparative differences of the GLAST, PPM1A, cleaved caspase-3, NF-κB in cytoplasm and NF-κB in nucleus among the four groups were statistically significant (F=135.20, 156.98, 80.96, 128.07, 47.36; all at P<0.01). The relative expression levels of GLAST, PPM1A and NF-κB protein in cytoplasm in the high-glucose group were significantly lower than those in the normal-glucose group, high-glucose+ 10 μmol/L berberine group and high-glucose+ 25 μmol/L berberine group (all at P<0.05). The relative expression levels of cleaved caspase-3 and NF-κB protein in nucleus in the high-glucose group were significantly higher than those in the normal-glucose group, high-glucose+ 10 μmol/L berberine group and high-glucose+ 25 μmol/L berberine group (all at P<0.05).

Conclusions

High-concentration glucose can induce cell apoptosis and inflammatory response of SD rats retinal Müller cells in vitro.However, berberine can inhibit cell apoptosis and inflammatory response induced by high-concentration glucose via suppressing NF-κB translocation and transcription activity, and thereby inhibiting the expression of inflammatory cytokines.