Orexin-A Prevents Lipopolysaccharide-Induced Neuroinflammation at the Level of the Intestinal Barrier

We examined a possible protective effect of OX-A against LPS-induced ROS formation and microglia activation. To mimic in vitro the connection between gut and brain and to study the putative effect on the cortical microglia, we used a co-culture of Caco-2 cells and primary cortical microglia with Caco-2 cells placed at the apical side of a transwell and primary cortical microglia at the basolateral side. All treatments used to study the apical vs. basal connection were applied to the apical compartment. We used DHR (10 μM, 20 min), a cell-permeable fluorogenic probe useful for the detection of ROS formation, to determine the LPS-induced ROS production and accumulation in the microglia. As shown in Figures 3B and 3E 6 h treatment of apical Caco-2 cells with LPS (0.5 μg/mL) led to ROS production and accumulation in the microglia of the basolateral compartment. This response was reduced by pre-exposure to OX-A (0.2 μM, 30 min before LPS; Figures 3C and 3E), whose protecting effect was abolished by treating the cells also with SB334867 (10 μM, added 15 min before OX-A; Figure 3D). In all these conditions, the size and number of cells were not affected by the treatments compared with untreated cells (Figures 3A and 3E). Next, we sought to investigate if OX-A has a protective effect by preventing microglia activation also in vivo. To corroborate this hypothesis, we treated mice with LPS (3.3 mg/kg, i.p., 6 h) and examined Iba-1 immunoreactivity in cor...
Source: Frontiers in Endocrinology - Category: Endocrinology Source Type: research