Painful diabetic neuropathy (PDN) is known to adversely affect psychosocial functioning by enhancing levels of anxiety and depression. This study was designed to verify the antihypernociceptive, anxiolytic, and antidepressant-like effects of Combretin A and Combretin B (two triterpenes cycloartane-type isolated from the leaves of Combretum fragrans) in streptozotocin-induced diabetic neuropathy in mice. PDN was induced in mice by the administration of streptozotocin (STZ, 200 mg/kg, i.p.). The effect of oral administration of Combretin A (25 and 50 mg/kg) and Combretin B (25 and 50 mg/kg) on nociception (mechanical allodynia, thermal hyperalgesia, cold allodynia, and chemical hyperalgesia), anxiety (elevated plus maze, light-dark box test, social interaction), and depressant (open field test, forced swimming test, tail suspension test) was evaluated. Combretin A (25 and 50 mg/kg) and Combretin B (25 and 50 mg/kg) caused antihypernociceptive, anxiolytic, and antidepressant-like effects in in STZ-induced diabetic neuropathy in mice. Both compounds also caused a decrease in blood glucose and improved body weight in treated animals. They also significantly (p < 0.001) reduced tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), malondialdehyde (MDA), and nitric oxide (NO) production in serum and sciatic nerves, and, significantly (p < 0.001) increased superoxide dismutase (SOD) and catalase (CAT) activity in serum, sciatic nerves, and brain. Combretin A and Combretin B also showed a great systemic effect, conserving values of evaluated parameters close to normal in treated mice. The results of this study confirm the antihypernociceptive, antianxiety, and antidepressant activities of Combretin A and Combretin B.
Keywords: Antihypernociceptive; Combretins A and B; Diabetic neuropathy; Neuroprotective.