Conclusion
MAN activated CAP by increasing peripheral Ach and up-regulating α7nAchR expression, which eventually led to NF-κB inhibition and remission of acute inflammations.
Methods
Male Sprague Dawley rats were pre-treated with MAN (40 mg/kg) for 3 days and ALI was induced with an intraperitoneal injection of lipopolysaccharide (LPS). Certain rats received monolateral vagotomy or sham surgery. The effects on inflammatory reactions and relevant pathways in ALI rats or LPS pre-treated RAW 264.7 cells were investigated by histological, immunohistochemical, immunoblotting, RT-qPCR, and immunofluorescence assays, while levels of proinflammatory cytokines, acetylcholine (Ach) and the enzymatic activity of acetylcholinesterase (AchE) were determined by corresponding quantitative kits.
Results
Oral administration of MAN reduced the severity of ALI, while vagotomy surgery antagonized this effect. MAN restored the decline in α7 nicotinic acetylcholine receptor (α7nAchR) in the lungs of ALI rats, and promoted the expression of α7nAchR and choline acetyltransferase (CHAT) in RAW 264.7 cells. Although AchE expression was barely affected by MAN at 5 μg/ml, its catalytic activity was reduced by almost 95%. Extracellular rather than intracellular Ach was notably raised shortly after MAN treatment. Furthermore, MAN at 5 μg/ml effectively inhibited LPS-induced increase in phosphorylation and nucleus translocation of p65 subunit, and secretion of TNF-α and IL-1β, which was then offset by methyllycaconitine citrate hydrate.