The protective role and mechanism of liriodendrin in rats with myocardial infarction

BACKGROUND: Liriodendrin is a therapeutic constituent of sargentgloryvine stem which is a famous Chinese traditional medicine. Previous studies have suggested liriodendrin could inhibit different pathways to treat inflammation in lung and intestinal tract. But whether it can treat myocardial infarction (MI) is unknown. We investigated the protective effect of liriodendrin on acute MI in rats and explored the specific mechanisms to expand the use of this traditional Chinese medicine. METHODS: The rats were randomized into the sham group (sham operation), control group (ligation of the left anterior descending artery), and liriodendrin group. The liriodendrin group was intragastrically administered with a liriodendrin solution (100 mg/kg). The control group and the sham group were intragastrically administered with normal saline. Before all rats were euthanized, echocardiography was used to detect their cardiac function. Hematoxylin and eosin (HE) staining and the terminal deoxynucleotidyl transferase-mediated nick end labeling (TUNEL) method were performed. Further quantitative detection of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) levels in tissues were also detected. Western Blot and real-time polymerase chain reaction (RT-PCR) were used to detect the apoptosis and nuclear factor kappa-B (NF-κB) pathway in tissues. H9C2 cells were used to detect the related mechanisms in vitro. RESULTS: Echocardiography showed that, compared to control group, the cardiac function of the liriodendrin group was significantly improved. histopathological staining of the control group showed that the myocardial tissue was severely damaged, and inflammatory cells were infiltrated. Compared to the control group, the apoptosis index of the liriodendrin group was significantly lower (P<0.05). Enzyme-linked immunosorbent assay (ELISA) results showed that the levels of IL-1β and TNF-α in the control group were higher than those in the liriodendrin group (P<0.05). Meanwhile, apoptosis and the NF-κB pathway were inhibited after liriodendrin administration (P<0.05). Moreover, the mRNA transcriptional activity in the control group was also higher than that in the liriodendrin group (P<0.05). Because of the effect of liriodendrin, NF-κB pathway and apoptosis were downregulated in H9C2 cells which were exposed to ischemia-hypoxia. CONCLUSIONS: Liriodendrin may protect myocardial cells after myocardial infarction in rats by inhibiting the release of inflammatory factors, activation of the NF-κB pathway, and apoptosis.