The protective role of tacrine and donepezil in the retina of acetylcholinesterase knockout mice

AIM

To determine the effect of different concentrations of the acetylcholinesterase (AChE) inhibitors tacrine and donepezil on retinal protection in AChE^+/− mice (AChE knockout mice) of various ages.

METHODS

Cultured ARPE-19 cells were treated with hydrogen peroxide (H₂O₂) at concentrations of 0, 250, 500, 1000 and 2000 µmol/L and protein levels were measured using Western blot. Intraperitoneal injections of tacrine and donepezil (0.1 mg/mL, 0.2 mg/mL and 0.4 mg/mL) were respectively given to AChE^+/− mice aged 2mo and 4mo and wild-type S129 mice for 7d; phosphate buffered saline (PBS) was administered to the control group. The mice were sacrificed after 30d by in vitro cardiac perfusion and retinal samples were taken. AChE-deficient mice were identified by polymerase chain reaction (PCR) analysis using specific genotyping protocols obtained from the Jackson Laboratory website. H&E staining, immunofluorescence and Western blot were performed to observe AChE protein expression changes in the retinal pigment epithelial (RPE) cell layer.

RESULTS

Different concentrations of H₂O₂ induced AChE expression during RPE cell apoptosis. AChE^+/− mice retina were thinner than those in wild-type mice (P<0.05); the retinal structure was still intact at 2mo but became thinner with increasing age (P<0.05); furthermore, AChE^+/− mice developed more slowly than wild-type mice (P<0.05). Increased concentrations of tacrine and donepezil did not significantly improve the protection of the retina function and morphology (P>0.05).

CONCLUSION

In vivo, tacrine and donepezil can inhibit the expression of AChE; the decrease of AChE expression in the retina is beneficial for the development of the retina.