Multiple factors and pathways involved in hepatic very low density lipoprotein-apoB100 overproduction in Otsuka Long-Evans Tokushima Fatty rats

Metabolic-Dysfunction-Associated Steatotic Liver Disease-Its Pathophysiology, Association with Atherosclerosis and Cardiovascular Disease, and Treatments

Metabolic-dysfunction-associated steatotic liver disease (MASLD) is a chronic liver disease that affects more than a quarter of the global population and whose prevalence is increasing worldwide due to the pandemic of obesity. Obesity, impaired glucose metabolism, high blood pressure and atherogenic dyslipidemia are risk factors for MASLD. Therefore, insulin resistance may be closely associated with the development and progression of MASLD. Hepatic entry of increased fatty acids released from adipose tissue, increase in fatty acid synthesis and reduced fatty acid oxidation in the liver and hepatic overproduction of triglyceride-rich lipoproteins may induce the development of MASLD. Since insulin resistance also induces atherosclerosis, the leading cause for death in MASLD patients is cardiovascular disease. Considering that the development of cardiovascular diseases determines the prognosis of MASLD patients, the therapeutic interventions for MASLD should reduce body weight and improve coronary risk factors, in addition to an improving in liver function. Lifestyle modifications, such as improved diet and increased exercise, and surgical interventions, such as bariatric surgery and intragastric balloons, have shown to improve MASLD by reducing body weight. Sodium glucose cotransporter 2 inhibitors (SGLT2i) and glucagon-like peptide-1 receptor agonists (GLP-1RAs) have been shown to improve coronary risk factors and to suppress the occurrence of cardiovascular diseases. Both SGLT2i and GLP-1 have been reported to improve liver enzymes, hepatic steatosis and fibrosis. We recently reported that the selective peroxisome proliferator-activated receptor-alpha (PPARα) modulator pemafibrate improved liver function. PPARα agonists have multiple anti-atherogenic properties. Here, we consider the pathophysiology of MASLD and the mechanisms of action of such drugs and whether such drugs and the combination therapy of such drugs could be the treatments for MASLD.

Effect of moderate exercises and curcumin on hepatic transcriptional factors associated with lipid metabolism and steatosis in elderly male rat

BACKGROUND AND PURPOSE

The specific molecular mediators involved in dyslipidemia in older people are not yet clearly understood. The current study was, thus, an attempt to investigate whether moderate aerobic exercises and curcumin administration alleviates the abnormalities caused by aging in the rats' liver.

EXPERIMENTAL APPROACH

Thirty-two eight-year-old young rats were classified into five groups, namely, young control, aged control, aged-curcumin, aged-exercise, and aged-curcumin-exercise co-treatment. The rats in the exercise groups were trained on an animal treadmill for 60 min/day five times per week for eight weeks.

FINDINGS/RESULTS

The results revealed a significant increase in FAT/CD36, PTP1B, significantly decreased HNF4α genes expression, increase in LDL and cholesterol in the aged group compared to the young control. Compared to those in the young control group, no significant changes in HDL and TG amounts in the aged control were observed. Moreover, compared to the young control, the aged group showed liver histological changes such as fibrosis and mild or grade 1 steatohepatitis. Moderate aerobic exercise and curcumin alone or in combination completely masked this effect.

CONCLUSION AND IMPLICATIONS

The findings revealed dyslipidemia and liver steatosis related to aging might be partly associated with changes in hepatic transcriptional factors which can be mitigated via moderate aerobic exercise and curcumin.

Apolipoprotein status in type 2 diabetes mellitus and its complications (Review)

Dyslipidaemia in type 2 diabetes mellitus (T2DM) is characterized by high plasma triglyceride concentrations, reduced high‑density lipoprotein concentrations and increased small density low‑density lipoprotein concentrations. Dyslipidaemia may lead to cardiovascular disease (CVD) and other complications. Apolipoproteins mainly comprise six species, apolipoprotein (apo)A, apoB, apoC, apoD, apoE and apoM, which are important components of plasma lipoproteins that carry lipids and stabilize the structure of lipoproteins. Complex metabolic disorders of apolipoproteins are present in T2DM, such as high plasma apoB, apoC‑II, apoC‑III and apoE concentrations, and low plasma apoA‑I and apoM concentrations, which are associated with dyslipidaemia and interrelated complications. Plasma concentrations of some apolipoproteins are also altered in T2DM with CVD or other complications. Several apolipoprotein polymorphisms are associated with diabetes susceptibility and/or lipid metabolism. The present review described the metabolic disorders of apolipoproteins in T2DM and its complications, and the relationship between each major apolipoprotein and T2DM, as well as the effects of apolipoprotein polymorphisms on diabetic susceptibility.

Metformin improves lipid metabolism disorders through reducing the expression of microsomal triglyceride transfer protein in OLETF rats

OBJECTIVE

This study aimed to investigate the role of MTP on lipid metabolism disorders in insulin-resistant rats and the potential mechanism through which metformin can improve lipid metabolism disorders.

METHODS

30 OLETF rats served as research subjects and 18 LETO rats of the same strain served as the control group (LETO group). After the first oral glucose tolerance test (at 8-week-old), 6 rats were randomly killed from each group. The remaining 24 OLETF rats were randomly divided into untreated group (OLETF group) and treated group (OLETF/M group, cured with metformin). By the end of the 10th and 20th week of treatment, MTP in the liver was measured for all rats in the study.

RESULTS

All OLETF rats exhibited diabetic phenotypes at 18-week-old, with their triglyceride level higher than in LETO rats at the same age. In OLETF rats, MTP level in the liver was higher than in LETO rats at 18-week-old, and the difference was significant at 28-week-old [(13.79±1.47) vs. (8.20±1.14), p<0.05]. Treatment with metformin for 20weeks decreased triglyceride [(1.06±0.23) vs. (2.20±0.62) mmol/L, p<0.05] and total cholesterol [(1.90±0.19) vs. (2.36±0.14) mmol/L, p<0.05] in OLETF rats. Metformin also decreased MTP level in the liver [(7.65±1.31) vs. (13.79±1.47), p<0.01].

CONCLUSIONS

MTP may be associated with the lipid metabolism disorder in OLETF rats and metformin could improve lipid metabolism through reducing the expression of MTP.