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Abstract Microglia activation and its mediated production of proinflammatory mediators play important roles in different neurodegenerative diseases; hence, modulation of microglia activation has been considered a potential therapeutic strategy to ameliorate neurodegeneration. This study was aimed to determine whether Gastrodin, a common herbal agent known to possess neuroprotective property, can attenuate production of proinflammatory mediators in activated microglia through the renin-angiotensin system (RAS) and Sirtuin3 (SIRT3). Expression of various members of the RAS including ACE, AT 1 , AT 2, and SIRT3 in activated microglia was assessed by immunofluorescence and Western blot in hypoxic-ischemia brain damage (HIBD) in postnatal rats, and in BV-2 microglia in vitro challenged with lipopolysaccharide (LPS) with or without Gastrodin treatment. Expression of NOX-2, a subunit of NADPH oxidase, and proinflammatory mediators including iNOS and TNF-α, was also evaluated. The present results showed that expression of ACE, AT 1 , NOX-2, iNOS and TNF-α was markedly increased in activated microglia in the corpus callosum of HIBD rats, and in LPS stimulated BV-2 microglia. Remarkably, the expression was markedly attenuated following Gastrodin treatment. Conversely, Gastrodin enhanced AT 2 and SIRT3 protein expression. In BV-2 microglia treated with Azilsartan, a specific inhibitor of AT 1 (AT 1 I group), NOX-2 expression was decreased whereas that of SIRT3 in LPS + AT 1 I and LPS + Gastrodin group was increased when compared with the controls. In LPS + AT 1 I + Gastrodin group, SIRT3 expression was further augmented. More importantly, Gastrodin effectively reduced caspase 3 protein expression level in the HIBD rats coupled with a significant decrease in caspase 3 positive cells. We conclude that Gastrodin can exert its protective effects against the hypoxic-ischemia brain damage in the present experimental HIBD model. It is suggested that this is mainly through suppression of expression of RAS (except for AT 2 and SIRT3) and proinflammatory mediators e.g. TNF-α in activated microglia. Highlights • Gastrodin suppresses renin-angiotensin system in activated microglia. • Gastrodin decreases proinflammatory mediators. • Gastrodin enhances SIRT3 expression in activated microglia. • Gastrodin acts through AT 1 receptor. [ABSTRACT FROM AUTHOR]

Scutellarin, an anti-inflammatory agent, has been reported to suppress microglia activation. It promotes astrocytic reaction but through activated microglia. Here we sought to determine more specifically the outcomes of scutellarin treatment in reactive astrocytes in rats subjected to middle cerebral artery occlusion (MCAO). GFAP, MAP-2 and PSD-95 expression was assessed in reactive astrocytes in scutellarin injected MCAO rats. Expression of BDNF, NT-3 and IGF-1, and cell cycle markers cyclin-D1/B1 was also evaluated. In vitro , the above-mentioned proteins were also investigated in TNC 1 and primary astrocytes, treated respectively with conditioned medium from BV-2 microglia with or without pretreatment of scutellarin and lipopolysaccharide. Behavioral study was conducted to ascertain if scutellarin would improve the neurological functions of MCAO rats. In MCAO, reactive astrocytes in the penumbral areas were hypertrophic bearing long extending processes; expression of all the above-mentioned markers was markedly augmented. When compared to the controls, TNC1/primary astrocytes responded vigorously to conditioned medium derived from BV-2 microglia treated with scutellarin + lipopolysaccharide as shown by enhanced expression of all the above markers by Western and immunofluorescence analysis. By electron microscopy, hypertrophic TNC1 astrocytes in this group showed abundant microfilaments admixed with microtubules. In MCAO rats given scutellarin treatment, neurological scores were significantly improved coupled with a marked decrease in infarct size when compared with the matching controls. It is concluded that scutellarin is neuroprotective and that it can amplify astrogliosis but through activated microglia. Scutellarin facilitates tissue remodeling in MCAO that maybe linked to improvement of neurological functions. [ABSTRACT FROM AUTHOR]