Effect of angiotensin II, angiotensin-(1-7) on insulin signaling pathway in NIT-1 cell line

Objective To evaluate the effect of angiotensin Ⅱ ( Ang Ⅱ ),angiotensin- (1-7) [ Ang- ( 1-7 ) ],and co-action of Ang Ⅱ and Ang-( 1-7 ) on β cell insulin signaling pathway.Methods Mouse pancreatic β cell line NIT-1 was incubated with( 1 )0,10-7,10-6,10-s,10-4 mol/L concentrations of Ang Ⅱ for 24 h ; ( 2 )0,10-7,10-6,10 -5,10-4 mol/L concentrations of Ang- ( 1-7 ) for 24 h; ( 3 ) co-administration of Ang Ⅱ and Ang- ( 1-7 ) was divided into control,10-5mol/L Ang Ⅱ,10-6mol/L Ang-( 1-7 ),10-5mol/L Ang Ⅱ + 10-6mol/L Ang-( 1-7 ) group.Tyrosine phosphorylation of insulin receptor β subunit(IR-β-Tyr) and serine phophorylation of protein kinase B(Akt-Ser) were detected by Western blot.Results Insulin-stimulated IR-β-Tyr and Akt-Ser phosphorylation was significantly decreased in Ang Ⅱ 10-5 and 10-4 mol/L group; no significant changes in insulin-stimulated IR-β-Tyr and Akt-Ser phosphorylation were detected between Ang-( 1-7 ) treatment groups and control; Ang-( 1-7 ) blocked the inhibitory effect of Ang Ⅱ on Akt-Ser phosphorylation,yet exerted no effect on Ang Ⅱ-induced IR-β-Tyr phosphorylation inhibition.Conclusion Ang Ⅱ significantly inhibits insulin signaling pathway in β cell; Ang-( 1-7 ) reverts the inhibitory effect of Ang Ⅱ on insulin-stimulated Akt-Ser phosphorylation in β cell.