Possible involvement of l-arginine–nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling pathway in the antidepressant-like effect of Wuling mycelia powder in rat

ContextWuling mycelia powder is the dry powder of rare a fungi Xyla ria sp., Carbon species, with a long history of medicinal use in Chinese medicine. Recently it has shown a powerful antidepressant activity in clinic.ObjectiveThe present study explores the antidepressant activity of Wuling mycelia powder in chronic unpredictable mild stress (CUMS) rats and its possible involvement of l-arginine–nitric oxide (NO)-cyclic guanosine monophosphate (cGMP) signaling pathway.Materials and methodsExperiments were performed in the rat CUMS model. CUMS rats were treated with Wuling mycelia powder (0.5, 1.0 or 2.0 g/kg, i.g.) to test behavioral changes including the sucrose preference, the crossing number and food consumption. Further, l-arginine (substrate for nitric oxide) (750 mg/kg), 7-nitroindazole (a specific neuronal nitric oxide synthase inhibitor) (25 mg/kg), sildenafil (phosphodiesterase 5 inhibitor) (5 mg/kg) and methylene blue (direct inhibitor of both nitric oxide synthase and soluble guanylate cyclase) (10 mg/kg) were treated for 60 min before each test to detect the possible mechanism of antidepressant-like effect of Wuling mycelia powder.ResultsAfter 4 weeks of administration, both 1.0 or 2.0 g/kg Wuling mycelia powder suppressed the behavioral changes including the sucrose preference [F(3, 31) = 50.87, p < 0.001], the crossing number [F(3, 31) = 68.98, p < 0.05], and food consumption [F(3, 31) = 19.04, p < 0.05] in the CUMS rats. The antidepressant-like effect of Wuling mycelia powder was prevented by pretreatment with l-arginine and sildenafil. Pretreatment of rats with 7-nitroindazole and methylene blue potentiated the effect of Wulin mycelia powder.Discussion and conclusionOur findings demonstrate that Wuling mycelia powder has an antidepressant-like effect in the CUMS rats, and possible involvement of l-arginine–nitric oxide–cyclic GMP signaling pathway in its antidepressant effect.