Participation of endocannabinoid system on TNF-alpha release from rat astrocytes after LPS

LUCE V; CARUSO C; CARNIGLIA L; LASAGA M; RETTORI V; DE LAURENTIIS A

San Petesburgo

Simposio; III International Symposium : Interactions of the nervous and immune systems in heallth and disease; 2011

Institute of Experimental Medicine, Rusia

It is known, that in response to several stimuli like bacterial endotoxins, astrocytes release proinflammatory mediators, such us TNF-alpha, which may play an important role in eliciting neuroinflammatory processes causing brain damage. Since cannabinoids have been reported to exert anti-inflammatory and neuroprotective actions in the brain, we examined the participation of the endogenous cannabinoid system on TNF-alpha release elicited by bacterial endotoxin lipopolysaccharide (LPS) in combination with interferon gamma (INF) in primary cultured rat astrocytes. Exposure of cultured astrocytes to LPS (1ug/ml) + INF (50ng/ml) during 90 min, 4 h and 24 hs significantly stimulated (p<0.001) TNF-alpha concentration in supernatants, determined by ELISA. CB1 and CB2 receptors are expressed by astrocytes and their activation by cannabinoid compounds regulates these cells functions. The presence of CB2 receptor antagonist (AM630, 10-5M) blocked the stimulatory effect of LPS+INF on TNF-alpha release, while CB1 antagonist (AM251, 10-5M) had no effect. The addition of the synthetic cannabinoid methanandamide (MetAEA, 10-9M) significantly decreased (p<0.01) basal TNF-alpha release but had a slight stimulatory effect on LPS-induced TNF-alpha release. Also, the addition of a fatty acid amide hydrolase inhibitor (URB597, 1uM) that increases endogenous anandamide levels, significantly decreased (p<0.01) basal TNF-alpha release and slightly decreased LPS-induced TNF-alpha levels. Taken together, these observations indicate that the endocannabinoid system modulates the release of TNF-alpha from astrocytes in culture and that the main effect appears to be mediated by CB2 receptors.