A New Approach for the Treatment of Diabetes and Nicotine Induced Cataract by Modulating Specific Ion-Channels Function in Rat Lens

Aim: Cataract is an eye disease characterized by a cloudiness of the normally transparent crystalline lens. Diabetes and smoking are the known risk factors for cataract development. It is well known fact that inorganic ions like Na+, K+, Ca++ and Cl- play an important role for the maintenance of lens hydration and transmittance. Nicotine aggravates cataract formation in diabetic patients by disturbing the ionic balance in the lens, generation of free radicals and disturbing normal lens physiology by generation of free radicals. Based upon these observations we have screened few drugs like Lidocaine, Nifedipine and Phenylglycine against Streptozotocin (STZ) + Nicotine induced cataract.
Methodology: Diabetes was induced by administration of combination of STZ (single dose of 52 mg/kg i.p.) and nicotine (0.3 mg/kg s.c) for 22 consecutive days and simultaneously treated with ophthalmic preparation of test drug i.e. Lidocaine, Nifedipine and Phenylglycine at 1% and 2% to the right and left eye respectively. On 23rd day of the study, various parameters like measurement of various ions (Na+, K+, Ca++ and Cl-), anti-oxidants (ascorbic acid, sulfhydral group, glutathione) and fructose content in rat lens were studied. We have also investigated the level of ascorbic acid in serum and monitored the blood glucose level at regular interval throughout the experiment.
Results: Accumulation of fructose in the lens cause malfunctioning of Na+-K+- ATPase pump which leads to accumulation of Na+ ions inside the membrane that causes to accretion of water and osmotic swelling of the lens. By the treatment with lidocaine (1% and 2%) eye drop significantly (P<0.001) reduced the Na+ content in both the eyes compared to disease control group.
Conclusion: In our study lidocaine has offered best protection against cataract. Phenylglycine has also shown protection but not as good as lidocaine, at the same time Nifedipine has not shown any protection.