modulation of lipopolysaccharide stimulated nuclear factor kappa b mediated inos/no production by bromelain in rat primary microglial cells

background: microglial cells act as the sentinel of the central nervous system .they are involved in neuroprotection but are highly implicated in neurodegeneration of the aging brain. when over-activated, microglia release pro-inflammatory factors, such as nitric oxide (no) and cytokines, which are critical in eliciting neuroinflammatory responses associated with neurodegenerative diseases. this study examined whether bromelain, the pineapple-derived extract, may exert an anti-inflammatory effect in primary microglia and may be neuroprotective by regulating microglial activation. methods: following the isolation of neonatal rat primary microglial cells, the activation profile of microglia was investigated by studying the effects of bromelain (5, 10, 20, and 30 µg/ml) on the levels of no, inducible nitric oxide synthase (inos), and nuclear factor kappa b (nf-&kappab;) in microglia treated with lipopolysaccharide (lps) (1 µg/ml). data were analyzed using student's t-test. p values less than 0.05 were considered to be statistically significant, compared with the lps-treated group without bromelain. results: results showed that pretreatment of rat primary microglia with bromelain, decreased the production of no induced by lps (1 µg/ml) treatment in a dose-dependent manner. bromelain (30 µg/ml) also significantly reduced the expression of inos at mrna level and nf-&kappab; at protein level. moreover, the study of mitochondrial activity in microglia indicated that bromelain had no cytotoxicity at any of the applied doses, suggesting that the anti-inflammatory effects of bromelain are not due to cell death. conclusion: bromelain can be of potential use as an agent for alleviation of symptoms in neurodegenerative diseases.