Crocin Inhibits Myocardial Fibrosis Through Regulating TLR4/NF-κB Signaling Pathway

Crocin is a kind of water-soluble carotenoids extracted from saffron.It is one of the main active ingredients of saffron and has anti-cancer,anti-inflammatory,anti-oxidation and anxiolytic effects.At present,Crocin plays an important role in the treatment of cardiovascular diseases,but the pharmacological effect and specific mechanism of Crocin in myocardial fibrosis(MF)have not been reported.Objective: To explore the protective effect and mechanism of Crocin on isoproterenol(ISO)-induced MF in mice.Methods: Fifty KM mice were randomly divided into five groups(n =10): control group(Control),ISO model group(10 mg/kg/day,ISO),and low-dose Crocin treatment group(100 mg/kg/day,ISO + L-Crocin),high-dose Crocin treatment group(200 mg/kg/day,ISO + H-Crocin),and propranolol treatment group(40 mg/kg/day,ISO + PRO).Control and ISO groups were given the same volume of saline.The ISO + L-Crocin group and the ISO +H-Crocin group were injected intraperitoneally with Crocin,the ISO + PRO group was injected intraperitoneally with PRO.The mice were subcutaneously injected with ISO(except for the Control group)for 14 days in all groups.Colorimetry,immunohistochemistry,RT-PCR and Western blot were used to observe the effects of Crocin on oxidative stress,inflammatory response,apoptosis and toll like receptor 4/nuclear factor-kappa B(TLR4/NF-κB)signaling pathway in MF mice induced by ISO.Result:Compared with the ISO group,administration of crocin(100,200 mg /kg)markedly decreased heart rate,J-point elevation,QRS interval,and cardiac weight index(CWI)in the myocardial tissues,and improved heart pathologic morphology.The levels of creatine kinase(CK)and lactate dehydrogenase(LDH)were significantly decreased.The content of hydroxyproline(Hyp)and malondialdehyde(MDA)were significantly decreased,while the activities of superoxide dismutase(SOD),catalase(CAT)and glutathione(GSH)were significantly increased.The expression of interleukin-1(IL-1),interleukin-6(IL-6),tumor necrosis factor-α(TNF-α),Bcl-2 related X protein(Bax),caspase-3 and cleared caspase-3 were significantly down-regulated,while the expression of B lymphoma-2 gene(Bcl-2)was significantly up-regulated.The m RNA and protein expression of transforming growth factor-β1(TGF-β1)and connective tissue growth factor(CTGF)were significantly down-regulated,and the protein expression of TLR4 and NF-κB were significantly down-regulated.Conclusion: Crocin has a protective effect on ISO-induced MF,and its mechanism may be related to the inhibition of TLR4/NF-κB signaling pathway,inhibition of oxidative stress,inflammatory response and apoptosis.