Endocrine Abstracts

This study investigated the role of muscarinic receptors and endothelial signaling pathways in the vascular relaxation promoted by Raphanus sativu. In our research for active constituents in Raphanus sativus with the potential for improving the vascular system, we evaluated the effect of Raphanus sativus on NO production in vascular endothelial cells. In the result, we found that the underlying mechanism for stimulating NO production by Raphanus sativus extract involves eNOS activation by the phosphorylation of Ser1177 and the dephosphorylation of Thr495, which are triggered by elevated concentrations of cytoplasmic Ca²⁺ resulting from the activation of Ca²⁺ channels in vascular endothelial cells. Several stimuli are known to activate eNOS through Akt-mediated phosphorylation of the enzyme. Hence, we evaluated the involvement of Akt in the phosphorylation and stimulation of eNOS by Raphanus sativus. Incubation with inhibitors of the MEK/ERK1/2 or p38MAPK pathways did not alter the Raphanus sativus vasorelaxation. Western blot analysis evidenced that Raphanus sativus induces phosphorylation of eNOS, PI3K and Akt in vascular endothelial cells. We identify PI3K/Akt pathways as critical mediators of the NO signaling activation by Raphanus sativus. These findings contribute to the notion that Raphanus sativus regulates arterial function and vascular dysfunction.