RESUMO
OBJECTIVES: Time-dependent effects of alpha-lipoic acid/nifedipine/glimepiride combination on diabetic neuropathies were investigated in rats. 7 groups (n=9) of rats were used. MATERIALS AND METHODS: First and second groups were apparently normal and diabetic rats respectively, and were administered 1mL/kg distilled water. The rest of the groups were diabetic and administered 10mg/kg glimepiride at night-time (8:00 pm). Groups 4-7 were administered additional 20mg/kg nifedipine at morning-time (8:00 am), while groups 5-7 were also administered 100mg/kg alpha-lipoic acid (ALA) in the morning, afternoon and night-time respectively (8:00 am, 2:00 pm and 8:00 pm). During the 28 days of oral treatment, paw pressure, tail immersion and motor coordination tests were conducted. The rats were euthanized on the 29th day after a charcoal meal. The small intestines were excised to determine intestinal transit while the brain was collected, homogenised and used to determine levels of oxidative stress. RESULTS: Data show that treatment with ALA at 8:00 am or 2:00 pm significantly (P≤0.01) produced a delay in the onset and improved prognosis of neuropathies. Treatment with ALA at 8:00 pm prevented manifestation of neuropathies throughout the study with positive antioxidant effects. CONCLUSION: Time-dependent ALA treatment in combination with nifedipine and glimepiride should be studied in humans with an approximately similar circadian timing. This may provide additional clinical therapeutic options for diabetic neuropathies.