Role of nNOS in the modulation of stress induced neuro behavioural patterns and its relation to Withania Somnifera:
Withania somnifera (Ashwagandha, Indian ginseng) is an herbal medicine used to improve overall health and prevent diseases. Studies have suggested its effect on stress. We investigated the role of methanolic extract from the root of Withania somnifera (WS) and the effect of its modulation in some stress-induced neurobehavioral patterns in rats using the Elevated Plus maze and Open field test. Nitric oxide (NO), a stable gaseous free radical, is now recognized as an important biomodulator. NO has been associated to anxiety, however, the role of NO and nNOS in stress and stress related behavioural changes is not clearly defined. We thus investigated the role of Withania Somnifera in modulation of brain NOx content and henceforth demonstrate the effect of Withania somnifera on stress via nNOS pathway.
We found that restraint stress (2 h) reduced both the number of entries and time spent in open arms, with both expressed as percent of controls (no restraint stress). Withania Somnifera (50 mg/ml) pretreatment showed increment in both these readings. The open arm entries and time spent in open arms were further increased by the NO precursor, L-arginine (1000 mg/kg) pretreatment. The nitric oxide synthase inhibitor, N-nitro-L-arginine methyl ester (L-NAME) (50 mg/kg), aggravated restraint stress effects in the elevated plus maze test. In the open field test, the restraint stress (a) increased entry latency and (b) decreased ambulation and rearing. These effects were reversed by Ashwagandha and L-Arginine, whereas L-NAME aggravated restraint stress effects. Biochemical data showed that the pretreatment with Ashwagandha and L-Arginine increased total brain nitrate/nitrite content, whereas the L-NAME (50 mg/kg) induced an opposite effect. The results demonstrate that Ashwagandha reduced stress induced patterns and produced a significant and concentration-dependent increase in NO, and WS enhances the effect of L-Arg. This gives us a scope for further research to study the role WS as an anxiolyte.
My final Thesis presentation with a brief overview of the data is below.