Activation of astrocytes by advanced glycation end products: cytokines induction and nitric oxide release

To investigate whether two kinds of in vitro prepared advanced glycation end products (AGE), Glu-BSA and Gal-BSA, could induce proinflammatory mediators IL-1beta and TNF-alpha, as well as oxidative stress and nitric oxide (NO), in astrocytes, thus contributing to brain injury.

Radioimmunoassay and RT-PCR technique were used to detect two cytokines' level and existence of receptor for AGE (RAGE). DTNB reaction was used to measure reduced glutathione (GSH) level. NO content was assayed using Griess reagent provided by Promega.

Enhanced protein levels of both cytokines in supernatants and cell lysates of astroglia cultures were detected after treated with AGE-BSA 1 g/L, especially Gal-BSA, for 72 h. The increases were also in a concentration-dependent manner. Changes in protein levels might be attributed to changes in transcriptional levels documented by semi-quantitative RT-PCR. Both AGE-BSA could also reduce astrocytic GSH and induce NO release. RAGE was detected in astrocytes.

Enhanced levels of astrocytic proinflammatory mediators IL-1beta and TNF-alpha, and oxidative stress caused by AGE might contribute to, at least partially, the detrimental effects of AGE in neuronal disorders and aging brain.