Aim: To determine whether angiotensin II receptor blockers (ARBs) could protect central neurons against nutrient deprivation-induced apoptosis in vitro and to elucidate the underlying mechanisms.
Methods: Primary rat cerebellar granule cells (CGCs) underwent B27 (a serum substitute) deprivation for 24 h to induce neurotoxicity, and cell viability was analyzed using LDH assay and WST-1 assay. DNA laddering assay and TUNEL assay were used to detect cell apoptosis. The expression of caspase-3 and Bcl-2, and the phosphorylation of Akt and GSK-3β were detected using Western blot analysis. AT1a mRNA expression was determined using RT-PCR analysis.
Results: B27 deprivation significantly increased the apoptosis of CGCs, as demonstrated by LDH release, DNA laddering, caspase-3 activation and positive TUNEL staining. Pretreatment with 10 μmol/L ARBs (telmisartan, candesartan or losartan) partially blocked B27 deprivation-induced apoptosis of CGCs with telmisartan being the most effective one. B27 deprivation markedly increased the expression of AT1a receptor in CGCs, inhibited Akt and GSK-3β activation, decreased Bcl-2 level, and activated caspase-3, which were reversed by pretreatment with 1 μmol/L telmisartan. In addition, pretreatment with 10 μmol/L PPARγ agonist pioglitazone was more effective in protecting CGCs against B27 deprivation-induced apoptosis, whereas pretreatment with 20 μmol/L PPARγ antagonist GW9662 abolished all the effects of telmisartan in CGCs deprived of B27.
Conclusion: ARBs, in particular telmisartan, can protect the nutrient deprivation-induced apoptosis of CGCs in vitro through activation of PPARγ and the Akt/GSK-3β pathway.