Pentose phosphate pathway of glucose-6-phosphate oxidation in the liver of rats with alloxan diabetes on the background of melatonin administrations and variable photoperiod

Objective: . Aim: To find out the influence of melatonin on the enzyme activities of glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and transketolase in the liver of rats with alloxan diabetes under conditions of variable photoperiod.

Patients and methods: Materials and Methods: Experiments were conducted on male outbred white rats weighing 180±10 mg. Photoperiodic changes: 1) equinox (light from 8:00 a.m. to 8:00 p.m., 500 lux); 2) light throughout the day and night (500 lux); 3) darkness. Alloxan diabetes was induced by administration of a 5% solution of alloxan monohydrate at a dose of 170 mg/kg once. Groups: 1) control; 2) rats with diabetes mellitus; 3) rats with diabetes mellitus and melatonin injections at the rate of 10 mg/kg of weight for a week daily. Rats were sacrificed on the 12th day in accordance with the ethical principles of experiments on animals. Enzyme activities were determined according to standard methods. Statistical processing was performed according to Statistica 10 StatSoft Inc.

Results: Results: In the liver of rats with diabetes mellitus, under the conditions of equinox activities of investigated enzymes decreased by 42, 32 and 40%, while an administration of melatonin let to: 1) an increase in enzyme activities by 40, 31, and 25%, respectively; 2) normalization under conditions of darkness; 3) an increase of the activities by 87, 120, and 60%, respectively in light conditions, compared to the control of equinox.

Conclusion: Conclusions: Melatonin contributed to the restoration of the amphibolic and energetic function of the pentose phosphate pathway of glucose-6-phosphate oxidation in liver of rats with alloxan diabetes under condition of variable photoperiod.