Fig. 1
From: Histamine induces microglia activation and dopaminergic neuronal toxicity via H1 receptor activation
Histamine-induced microglial FcγR-mediated phagocytosis through H1R activation. a Representative photomicrographs illustrate the stimulatory effect of 100 μM histamine on microglial phagocytosis of IgG latex beads. Non-ingested beads display red labeling whereas ingested beads do not show any fluorescence signal. Scale bar 10 μm. b Only 10 (H10) and 100 (H100) μM histamine significantly increased the number of phagocytosed IgG latex beads per cell as compared with untreated controls (Ctr). Microglial phagocytosis induced by 100 μM histamine was fully blocked by an H1R antagonist (AntH1R, mepyramine maleate, 1 μM) and mimicked by an H1R agonist (AgH1R, 4-methylhistamine dihydrochloride, 20 μM). The involvement of other receptors was excluded since the application of their respective antagonists (“Ant”) did not interfere with the phagocytosis-inducing effect of histamine (H2R antagonist (cimetidine), 5 μM; H3R antagonist (carcinine ditrifluoroacetate), 5 μM; and H4R antagonist (JNJ7777120), 5 μM). Data are expressed as mean ± SEM (n = 5–15). *P < 0.05 and ***P < 0.001, using one-way ANOVA followed by Bonferroni’s multiple comparison test