ABSTRACT
Aim To investigate the effect of histamine H, receptor (HjR) on the immune responses in astrocytes induced by lipopolysaccharide (LPS) and the regulatory mechanism of its signaling pathway. Methods LPS was used to establish an in vitro astrocyte inflammation model. Rat primary astrocytes were divided into the control group, LPS group, LPS + Hj R agonist group (2-pyridylethlamine, Pyri), and HjR agonist group. Astrocytes were treated with Pyri 100 p,mol • L~ for 1 h, then stimulated with LPS at 100 p,g • L~ for 24 h. Cell viability was measured using the CCK-8 assay. The expression of GFAP and HjR was detected by immunofluorescence. Glial morphological changes were observed under a microscope. The levels of proinflammatory mediators (TNF-a and IL-6) were detected by ELISA. The protein expressions of p-Akt, Akt, p-NF-KB p65, and NF-KB p65 were detected by Western blot. Results Compared with the control group, more activated astrocytes with fewer cell processes and branches were observed in the LPS group. Besides, LPS enhanced the GFAP expression level, reduced the H,R expression level and stimulated the production of TNF-a and IL-6 from astrocytes. Pre treatment with Pyri for 1 h ameliorated the glial morphological changes stimulated by LPS, inhibited LPS-induced upregulation of GFAP level and the inflammatory factors secretion. In addition, LPS stimulated astrocytes showed a higher phosphorylation of Akt and NF-KB p65, which was also ameliorated by Pyri. Conclusions H, R agonist can inhibit LPS-induced astrocyte activation and inflammatory factor secretion, and the Akt/NF-KB signaling pathway may be an important pathway for the involvement of H,R in immune regulation.