α2-adrenoceptor agonist B-HT933 suppresses LPS-induced TNF-α production in neonatal rat cardiomyocytes

AIM: To observe the effect of B-HT933, a selective α₂-adrenoceptor agonist, on lipopolysaccharide(LPS)-induced TNF-α production in neonatal rat cardiomyocytes and to explore the underlying mechanisms.METHODS: The neonatal rat cardiomyocytes were cultured. The localization of α_2A-adrenoceptor in the cardiomyocytes was examined by immunofluorescence staining. The cardiomyocytes were exposed to LPS or/and B-HT933 for different time. The level of TNF-α in the supernatants and the mRNA expression of TNF-α were detected by ELISA and real-time PCR, respectively. In addition, LPS-associated signal molecules in the cardiomyocytes were also examined by Western blotting.RESULTS: Immunofluorescence staining showed that α_2A-adrenoceptors were localized in the cardiomyocytes. LPS stimulated TNF-α production in the cardiomyocytes in a dose and time-dependent manner. B-HT933 pretreatment significantly inhibited the expression of TNF-α at mRNA and protein levels in LPS-treated cardiomyocytes. Furthermore, LPS exposure induced IκBα and p38 phosphorylation in cardiomyocytes and only IκBα phosphorylation was prevented by B-HT933 treatment.CONCLUSION: α_2A-adrenoceptors are present in neonatal rat cardiomyocytes and its agonist B-HT933 inhibits LPS-induced TNF-α production in cardiomyocytes via suppressing IκBα phosphorylation.