Berberine Ameliorates Obesity by Inducing GDF15 Secretion by Brown Adipocytes

Berberine attenuates obesity-induced insulin resistance by inhibiting miR-27a secretion

INTRODUCTION

Berberine (BBR) is an alkaloid found in plants. It has neuroprotective, anti-inflammatory and lipid-lowering activity. However, the efficacy of treatment with BBR and the mechanisms through which it acts need further study.

AIMS

This study investigated the therapeutic effects and the mechanism of action of BBR on obesity-induced insulin resistance in peripheral tissues.

METHODS

High-fat-fed C57BL/6J mice and low-fat-fed C57BL/6J mice with miR-27a overexpression were given BBR intervention (100 mg/kg, po), and the oral glucose tolerance test (OGTT) and insulin tolerance test (ITT) were performed. Palmitic acid-stimulated hypertrophic adipocyte models were treated with BBR (10 μM). Related indicators and protein expression levels were examined.

RESULTS

The AUCs of the OGTT and the ITT in the BBR intervention group were reduced significantly (p < 0.01) (p < 0.05), and the serum biochemical parameters, including FBG, TC, TG and LDL-C were significantly reduced after BBR intervention. In the in vitro experiments, the triglyceride level and volume of lipid droplets decreased significantly after BBR intervention (p < 0.01) (p < 0.05). Likewise, BBR ameliorates skeletal muscle and pancreas insulin signalling pathways in vivo and in vitro.

DISCUSSION

The results showed that BBR significantly ameliorated insulin resistance, reduced body weight and percent body fat and improved serum biochemical parameters in mice. Likewise, BBR reduced triglyceride level and lipid droplet volume in hypertrophic adipocytes, BBR improved obesity effectively. Meanwhile, BBR ameliorated the histomorphology of the pancreas, and skeletal muscle and pancreas insulin related signalling pathways of islets in in vitro and in vivo experiments. The results further demonstrated that BBR inhibited miR-27a levels in serum from obese mice and supernatant of hypertrophic adipocytes. miR-27a overexpression in low-fat fed mice indicated that miR-27a caused insulin resistance, and BBR intervention significantly improved the miR-27a induced insulin resistance status.

CONCLUSION

This study demonstrates the important role of BBR in obesity-induced peripheral insulin resistance and suggest that the mechanism of its effect may be inhibition of miR-27a secretion.

Gut microbiota in overweight and obesity: crosstalk with adipose tissue

Overweight and obesity are characterized by excessive fat mass accumulation produced when energy intake exceeds energy expenditure. One plausible way to control energy expenditure is to modulate thermogenic pathways in white adipose tissue (WAT) and/or brown adipose tissue (BAT). Among the different environmental factors capable of influencing host metabolism and energy balance, the gut microbiota is now considered a key player. Following pioneering studies showing that mice lacking gut microbes (that is, germ-free mice) or depleted of their gut microbiota (that is, using antibiotics) developed less adipose tissue, numerous studies have investigated the complex interactions existing between gut bacteria, some of their membrane components (that is, lipopolysaccharides), and their metabolites (that is, short-chain fatty acids, endocannabinoids, bile acids, aryl hydrocarbon receptor ligands and tryptophan derivatives) as well as their contribution to the browning and/or beiging of WAT and changes in BAT activity. In this Review, we discuss the general physiology of both WAT and BAT. Subsequently, we introduce how gut bacteria and different microbiota-derived metabolites, their receptors and signalling pathways can regulate the development of adipose tissue and its metabolic capacities. Finally, we describe the key challenges in moving from bench to bedside by presenting specific key examples.

Pharmacokinetics, Tissue Distribution and Excretion of Demethyleneberberine, a Metabolite of Berberine, in Rats and Mice

Demethyleneberberine is an active component extracted from the Chinese herbal drug Cortex Phellodendri. It is also a metabolite of berberine in animals and humans. However, the pharmacokinetics, tissue distribution and excretion of demethyleneberberine have not been reported. The present study aimed to investigate the pharmacokinetic parameters of demethyleneberberine by applying high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS). After intragastric administration of demethyleneberberine in rats and mice, the pharmacokinetics, tissue distribution and excretion of demethyleneberberine were comparatively studied for the first time. The plasma concentration of demethyleneberberine reached its peak within 5 min after intragastric administration in both rats and mice. Furthermore, its bioavailability was comparable, ranging from 4.47% to 5.94%, higher than that of berberine. The total excretion of demethyleneberberine in the urine, feces and bile was 7.28~9.77%. These findings provide valuable insights into the pharmacological and clinical research on demethyleneberberine.