Nicotine promotes development of bile duct ligation-induced liver fibrosis by increasing expression of nicotinic acetylcholine receptors in rats.

Aim of the study: Liver fibrosis and cigarette smoking seem to be directly linked. Nicotine, as an agonist of nicotinic acetylcholine receptors (nAChRs), induces many downstream signaling pathways. The pathways through which nicotine affects the process of liver fibrosis have not been clarified. The present study aimed to investigate the nicotine-induced effects on fibrosis progression in cholestatic rats. Material and methods: First, the Wistar rats were subjected to sham or bile duct ligation (BDL) surgery. The rats were treated with low and high doses of nicotine (1 or 10 mg/kg) for three weeks. They were monitored for their body weights before and 21 days after BDL. Also, spleens were weighed to calculate the spleen/body weight ratio. Ductular proliferation and fibrosis were evaluated using hematoxylin and eosin (H&E) as well as Masson's trichrome staining. The mRNA expression of α4nAChR, α7nAChR, and fibrosis gene α-smooth muscle actin (α-SMA) was measured by real-time PCR. Results: The findings showed that nicotine promotes the development of BDL-induced liver fibrosis. The ratio of spleen/body weight was significantly affected by nicotine exposure. H&E and Masson's trichrome staining showed that the level of liver fibrosis was higher in the cholestatic BDL groups, and this effect was significantly augmented in the nicotine-treated rats. Also, α4nAChR, α7nAChR, and α-SMA expression was observed in the BDL rats and increased following nicotine treatment. Conclusions: The activation of nAChR triggers biliary proliferation and liver fibrosis. Studying the intracellular mechanism of nicotine and alteration in the expression of nicotinic receptors following nicotine exposure can be useful both in diagnosing nicotine-related diseases and finding new treatment strategies.

Effects of nicotine on microRNA-124 expression in bile duct ligation-induced liver fibrosis in rats.

BACKGROUND: Nicotine, the main compound of smoking may exert its effects by changing the expression of microRNAs (miRNAs). This study was conducted to further investigate the molecular mechanisms of miRNA-dependent effects of nicotine in an animal model of liver fibrosis. METHODS: The bile duct ligation (BDL) approach was used to create a model of liver fibrosis. Twenty-four male Wistar rats were used in the study. The effects of nicotine administration on miRNA-124 expression, as well as alpha-smooth muscle actin (liver fibrosis marker) and chemokine ligand 2 (an inflammatory chemokine), were investigated using RT-qPCR. In addition, the mRNA and protein expression of signal transducer and activator of transcription 3 (STAT-3; as a potential target for miRNA-124) were investigated by RT-qPCR and immunofluorescence, respectively. Liver enzyme activity levels were measured using a colorimetric assay. In addition, the effects of nicotine on the process of liver fibrosis were investigated with histological studies. RESULTS: The development of liver fibrosis in BDL rats and nicotine administration led to a decrease in miRNA-124 expression. The decrease in the expression is accompanied by the increase in the expression of fibrotic and proinflammatory genes. Also, an increase in STAT-3 mRNA and protein expression was observed in the fibrotic rats that received nicotine. In addition, the significant increase in bilirubin and liver enzymes in fibrotic rats worsens with nicotine administration. The results of histological studies also confirm these results. CONCLUSION: Considering that miRNA-124 is an anti-inflammatory miRNA, it can be concluded that the decrease in its expression due to nicotine exposure leads to an increase in inflammatory processes and subsequently to an increase in liver fibrosis.

Effect of ghrelin on hypoxia-related cardiac angiogenesis: involvement of miR-210 signalling pathway.

OBJECTIVE: Hypoxia is the main stimulus for angiogenesis. Hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), and miR-210 are involved in the hypoxia-induced angiogenesis. This study examined the effects of hypoxia and/or ghrelin on miR-210, HIF-1α, and VEGF levels in the heart of rats. METHODS: Wistar rats were randomly divided into 4 groups (n = 6): control; ghrelin, received daily intraperitoneal injections of ghrelin; hypoxia, was exposed to hypoxic condition; hypoxia + ghrelin, was exposed to hypoxic condition and received intraperitoneal injections of ghrelin, for 2 weeks. Myocardial angiogenesis, the expression level of miR-210, and protein levels of HIF-1α and VEGF were assayed in the heart samples. RESULTS: Hypoxia increased myocardial angiogenesis and cardiac levels of miR-210, HIF-1α, and VEGF. However, ghrelin inhibited these hypoxia-induced changes. Interestingly, ghrelin had no significant effect on miR-210, HIF-1α, and VEGF levels in normoxic condition. CONCLUSION: Ghrelin may be useful as an anti-angiogenic factor.

Hepatoprotection of capsaicin in alcoholic and non-alcoholic fatty liver diseases.

Alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD) are common causes of chronic liver disease that share the range of steatosis, steatohepatitis, fibrosis, cirrhosis, and finally, hepatocellular carcinoma. They are identified by the dysregulation of disease-specific signalling pathways and unique microRNAs. Capsaicin is an active ingredient of chilli pepper that acts as an agonist of transient receptor potential vanilloid subfamily 1. It seems that the protective role of capsaicin against NAFLD and ALD is linked to its anti-steatotic, antioxidant, anti-inflammatory, and anti-fibrotic effects. Capsaicin-induced inhibiting metabolic syndrome and gut dysbiosis and increasing bile acids production are also involved in its anti-NAFLD role. This review summarises the different molecular mechanisms underlying the protective role of capsaicin against NAFLD and ALD. More experimental studies are needed to clarify the effects of capsaicin on the expression of genes involved in hepatic lipid metabolism and hepatocytes apoptosis in NAFLD and ALD.

Protective Effect of Trans-chalcone Against High-Fat Diet-Induced Pulmonary Inflammation Is Associated with Changes in miR-146a And pro-Inflammatory Cytokines Expression in Male Rats.

High-fat diet (HFD) increases the risk of non-communicable inflammatory diseases including pulmonary disorders. Trans-chalcone is a chalcone with antioxidant and anti-inflammatory effects. This study aimed to explore the effect of this natural compound and molecular mechanism of its effect on HFD-induced pulmonary inflammation. Twenty-eight male Wistar rats were randomly divided into four main groups (n = 7 per each group): control, receiving 10% tween 80; Chal, receiving trans-chalcone, HFD, receiving a high-fat emulsion and 10% tween 80; HFD + Chal, receiving a high-fat emulsion and trans-chalcone. After 6 weeks, the lungs were dissected, and the expression levels of tumor necrosis factor-α (TNF-α), interleukin-1ß (IL-1ß), interleukin-6 (IL-6), and miR-146a were determined using real-time PCR. Moreover, histological analysis was done by hematoxylin and eosin staining. Significant elevations in TNF-α, IL-1ß, IL-6, and miR-146a expression levels (P < 0.001) were observed within the lungs of HFD-fed rats compared with the control. However, oral administration of trans-chalcone reduced TNF-α, IL-1ß, IL-6 (P < 0.001), and miR-146a (P < 0.05) expression levels and also improved HFD-induced histological abnormalities. These findings indicate that trans-chalcone ameliorates lung inflammatory response and structural alterations. It seems that this beneficial effect is associated with the down-regulation of pro-inflammatory cytokines and miR-146a.

Inhibition of PTEN protects PC12 cells against oxygen-glucose deprivation induced cell death through mitoprotection.

Mitochondria involve in the determination of ischemic neuronal cell fate through regulation of apoptotic and necrotic cell death. Phosphatase and tensin homolog (PTEN) protein negatively regulates Akt/PKB signaling which is the major cell survival pathway. The current study aimed to examine the impact of SF1670, a potent PTEN inhibitor, on mitochondria-mediated cell survival pathways in an in vitro stroke-like model. PC12 cells were exposed to one hour oxygen and glucose deprivation (OGD) followed by different time points of reperfusion (0, 30, 60, 120 and 180 min) and SF1670 treatments. Our findings showed that OGD/R exposure increased reactive oxygen species (ROS) levels, reduced phosphorylated Akt (p-Akt), ratios of Bcl-2/BAX, intracellular ATP, mitochondrial vital activity and mitochondrial membrane potential (Δψm). OGD/R exposure also increased cleaved caspase 3/pro-caspase 3 and cleaved caspase 9/pro-caspase 9 ratios associated with low cell viability, high lactate dehydrogenase (LDH) release, and greater apoptotic cell death in the TUNEL assay. Conversely, inhibition of PTEN by SF1670 were associated with increased expression of p-Akt and anti-apoptotic proteins (Bcl-2), attenuated pro-apoptotic proteins (BAX) and oxidative stress index (ROS), improved mitochondrial function (restored MMP and ATP), and decreased apoptotic cell death. These results strongly suggest that neuroprotective effect of SF1670 against OGD/R-induced cell death at least is partially mediated through mitoprotective properties of SF1670.

Chalcones as putative hepatoprotective agents: Preclinical evidence and molecular mechanisms.

Chalcones form an important group of natural compounds and flavonoid precursors which are abundant in fruits, vegetables, and edible plants. These compounds have many beneficial properties including anti-inflammatory, anti-microbial, antioxidant, anti-cancer, anti-amyloid, anti-diabetic, anti-obesity, hypolipidemic, and cytoprotective. Chalcone derivatives have protective effects on the liver in nonalcoholic fatty liver disease, alcoholic fatty liver, drug- and toxicant-induced liver injury, and liver cancer through several mechanisms. Chalcones improve adipocytes function and adiponectin secretion. They inhibit triglyceride synthesis, activating factors of hepatic stellate cells and extracellular matrix deposition and also elevate fatty acid oxidation. These effects of chalcones lead to liver injury improvement. In conclusion, chalcones with antioxidant, anti-fibrotic, and anti-inflammatory properties decrease liver injury markers and histological abnormality in liver injury.