Mechanisms Responsible For Protection Of Berberine And Yohimbine Against Endotoxemic Cardiac Dysfunction In Mice

ObjectiveTo observe the effects of berberine (Ber) and yohimbine (Y) on cardiac dysfunction in endotoxemic mice and further explore the mechanisms of their actions for providing an effective therapeutic strategy in the treatment of septic cardiac dysfunction.MethodsFirstly, The mice were randomly divided into eight groups:control, LPS, Ber+ LPS, Ber+ yohimbine+ LPS, yohimbine+ LPS, Ber, Ber+ yohimbine and yohimbine group. We examined the effects of berberine and yohimbine on the cardiac function at 12h after LPS challenge with VisualSonicsR Vevo770TM High-Resolution In Vivo Imagine System, and observed the histological changes of the heart. Secondly, we measured the level of myocardial malondialdehyde (MDA), superoxide dismutase (SOD) and myeloperoxidase (MPO) in the heart, and further investigated the effects of berberine and yohimbine on the cardiac tumor necrosis factor-a (TNF-a), interleukin-1β(IL-1β) and nitric oxide (NO) contents with enzyme-linked immunosorbent assay (ELISA) and the technique of nitrate reductase. Thirdly, we determined apoptosis and the activation of caspase-3 in the heart of mice challenged LPS. Lastly, we assessed the expression of Toll-Like Receptor-4 (TLR-4) mRNA and myocardial inhibitor of nuclear factor xκBα(IκBα) phosphorylation.Results1. In the histological examination, inflammation was observed in the heart tissue in the LPS group. Pretreatment with Ber, Ber combined with yohimbine or yohimbine obviously attenuated heart injury. Berberine and yohimbine could enhance the systole and diastole function of heart and prevent myocardial dysfunction in endotoxemic mice.2. There was no distinct among all groups in the levels of myocardial MDA and SOD. Compared with the control group, LPS administration increased the level of myocardial MPO. Pretreatment with Ber and Ber combined with yohimbine but not yohimbine significantly reduced the amount of MPO in the heart. LPS-stimulated cardiac TNF-α, IL-1βand NO production are inhibited by pretreatment with Ber or/and yohimbine.3. Pretreatment with Ber, Ber combined with yohimbine or yohimbine decreased cardiomyocyte apoptosis and supressed the activity of caspase-3 in the heart of endotoxemic mice.4. The expression of TLR-4 mRNA had no significant difference in the heart 1h after LPS challenge among the groups. Pretreatment with Ber, Ber combined with yohimbine or yohimbine inhibit LPS-induced IκBαphosphorylation in the heart.ConclusionBerberine and yohimbine prevent myocardial dysfunction in endotoxemic mice, via inhibiting the activity of myocardial caspase-3, decreasing apoptosis and supressing myocardial IκBαphosphorylation and in turn inhibiting cardiac TNF-α, IL-1βand NO production. These actions of Ber are not due to its activation ofα2-adrenergic receptor, activation ofα2-adrenoceptor is involved in the pathogenesis of LPS-induced cardiac dysfunction, Ber in combination with yohimbine might provide a novel therapeutic approach to myocardial dysfunction during sepsis.