Harmaline attenuates chemotherapy-induced peripheral neuropathy: Modulation of Nrf-2 pathway and NK-1 receptor signaling

Peripheral neuropathy, resulting from damage to peripheral nerves, manifests as weakness, numbness, and pain, primarily affecting extremities and significantly impairing quality of life, especially in the elderly. Current treatments often entail severe side effects, necessitating the exploration of alternative therapies. Harmaline, a β-carboline alkaloid derived from Peganum harmala, exhibits promising antioxidant and anti-inflammatory properties. This study aimed to assess the efficacy of harmaline in a vincristine-induced mouse model of peripheral neuropathy. Swiss albino mice received vincristine (0.1 mg/kg, i.p.) for 10 days to induce neuropathy. Harmaline (5 and 10 mg/kg, i.p.) was administered 30 min before vincristine and continued until day 14 to evaluate its protective effects. Behavioral assessments were conducted on days 7 and 14. Vincristine treatment significantly heightened sensitivity to cold, measured by cold plate and acetone drop tests, and to heat, assessed via the hot plate test, while also impairing motor coordination. Biochemical analyses revealed decreased levels of GSH and Nrf-2, alongside elevated TBARS and IL-1β levels in sciatic nerve tissue. Harmaline administration markedly alleviated both behavioral and biochemical alterations induced by vincristine, with the 10 mg/kg dose exhibiting the most pronounced effects. Notably, harmaline treatment elevated GSH and Nrf-2 levels while reducing TBARS and IL-1β. Furthermore, substance-P treatment reversed the protective effects of harmaline, implicating the NK-1 receptor in its mechanism of action. In conclusion, harmaline demonstrates significant potential in mitigating vincristine-induced peripheral neuropathy by reducing oxidative stress through Nrf-2 activation and lowering IL-1β levels, likely via NK-1 receptor inhibition.