Mid to distal small bowel resection with the preservation of the terminal ileum improves glucose homeostasis in diabetic rats by activating the hindgut-dependent mechanism

The role of weight control in the management of type 2 diabetes mellitus: Bariatric surgery

Diabetes mellitus is one of the major epidemics in the United States. It is heavily associated with obesity and multiple metabolic derangements that lead to long term morbidity, mortality as well as financial burden. Although medical therapy has been the mainstay in the management of diabetes mellitus, there remains a large portion of this patient population which struggles to obtain adequate glycemic control and long-term weight control with medical management alone. Bariatric surgery is a powerful tool in combating diabetes mellitus and affects glucose homeostasis through a variety of pathways. While it does provide a durable pathway for weight loss, improvement in glucose homeostasis is not only affected by the weight loss seen after bariatric surgery. Changes in gut hormone secretion, insulin regulation, and gut microbial composition also affect how these operations improve glucose homeostasis. Through improvement in the management of diabetes mellitus, comorbidities including cardiovascular disease, in turn demonstrate improvement. In this article, we will discuss the role of bariatric (metabolic) surgery as it relates to long term weight loss and the impact that weight loss has on improvement in diabetes mellitus.

Endocrine implications of bariatric surgery: a review on the intersection between incretins, bone, and sex hormones

Bariatric surgery is now the most widely used intervention for the treatment of human obesity. A large body of literature has demonstrated its efficacy in sustained weight loss and improvement in its associated comorbidities. Here, we review the effect of bariatric surgery in gut hormone physiology, bone remodeling and the reproductive axis. Rapid improvements in insulin release and sensitivity appear to be weight loss independent and occur immediately after surgery. These effects on pancreatic beta cells are mostly due to increased gut hormone secretion due to augmented nutrient delivery to the small intestine. Bone remodeling is also affected by gut hormones. Phenotypic skeletal changes observed in mice deficient in GLP-1 or GIP suggest that increased incretins may improve bone density. However, these positive effects may be counterbalanced by the association between weight loss and a reduction in bone density. Finally, studies have shown a marked improvement following bariatric surgery in infertility and PCOS in women and hypogonadism in men. Thus, the net effect on endocrine systems after bariatric surgery will likely vary on an individual basis and depend on factors such as comorbidities, peri-menopausal state, amount of weight loss, and likelihood to adhere to vitamin supplementation after surgery.

The histomorphometric parameters of endocrine pancreas after bariatric surgery in healthy animal models

BACKGROUND

The aim of this study is to describe in depth how different bariatric surgeries affect to the cellularity of β-cells in the pancreatic islet. There are much data regarding the possible physiological mechanisms involved in resolution of type 2 diabetes after bariatric surgery. But these data usually are controversial. We reported a direct influence of bariatric surgical technique on endocrine pancreas cellular turnover. Some surgeries increase proliferation processes of the β-cells. Our objective is to report the histomorphometric mechanism that these techniques stimulate over the cellularity of pancreatic islet.

METHOD

To this purpose, we used adult male Wistar rats to undergo the different techniques. We developed three surgical techniques (Sleeve gastrectomy and Y-Roux Gastric bypass as the most usual bariatric techniques, and a purely malabsorptive technique); moreover two control groups were performed (Sham and fasting controls).

RESULTS

We completed a sequence of morphometric studies to conclude the behaviour of endocrine pancreatic β-cell islet, correlating several histomorphometry parameters.

CONCLUSION

Our purpose was to show a comprehensive interpretation to the consequences that bariatric surgeries had on the pancreatic islets cellularity. Moreover, we included the main tests to report the cellularity in histological samples.

Metabolomics-based evidence of the hypoglycemic effect of Ge-Gen-Jiao-Tai-Wan in type 2 diabetic rats via UHPLC-QTOF/MS analysis

ETHNOPHARMACOLOGICAL RELEVANCE

Ge-Gen-Jiao-Tai-Wan (GGJTW) formula, derived from traditional Chinese herbal medicine, is composed of Pueraria montana var. lobata (Willd.) Sanjappa & Pradeep (Ge-Gen in Chinese), Coptis chinensis Franch (Huang-Lian), and Cinnamomum cassia (L.) J. Presl (Rou-Gui). GGJTW is used for treatment of diabetes in China, reflecting the potent hypoglycemic effect of its ingredients. However, little is known of the hypoglycemic effect of GGJTW and the underlying metabolic mechanism.

AIM OF THE STUDY

This study aimed to investigate the hypoglycemic effect of GGJTW in type 2 diabetic rats and the metabolic mechanism of action.

MATERIALS AND METHODS

Ultra high-performance liquid chromatography coupled with quadrupole-time-of-flight tandem mass spectrometry (UHPLC-QTOF/MS)-based metabolomics approach was used for monitoring hyperglycaemia induced by high-sugar high-fat fodder and streptozotocin (STZ), and the protective effect of GGJTW. Dynamic fasting blood glucose (FBG) levels, body weight, and biochemical parameters, including lipid levels, hepatic-renal function, and hepatic histopathology were used to confirm the hyperglycaemic toxicity and attenuation effects. An orthogonal partial least squared-discriminant analysis (OPLS-DA) approach highlighted significant differences in the metabolome of the healthy control, diabetic, and drug-treated rats. The metabolomics pathway analysis (MetPA) and Kyoto encyclopedia of genes and genomes (KEGG) database were used to investigate the underlying metabolic pathways.

RESULTS

Metabolic profiling revealed 37 metabolites as the most potential biomarker metabolites distinguishing GGJTW-treated rats from model rats. Most of the metabolites were primarily associated with bile acid metabolism and lipid metabolism. The most critical pathway was primary bile acid biosynthesis pathway involving the up-regulation of the levels of cholic acid (CA), chenodeoxycholic acid (CDCA), taurocholic acid (TCA), glycocholic acid (GCA), taurochenodesoxycholic acid (TCDCA), and taurine.

CONCLUSIONS

The significantly-altered metabolite levels indicated the hypoglycemic effect of GGJTW on diabetic rats and the underlying metabolic mechanism. This study will be meaningful for the clinical application of GGJTW and valuable for further exploration of the mechanism.

Side-to-Side Jejunoileal Bypass Induces Better Glucose-Lowering Effect than End-to-Side Jejunoileal Bypass on Nonobese Diabetic Rats

BACKGROUND

Jejunoileal bypass (JIB) can markedly ameliorate diabetes in obese patients and rodents. The aim of this study is to systematically evaluate the role of the operational manner and the retained distal small bowel length in mediating changes in glucose homeostasis after intestinal bypass surgeries in nonobese diabetic rats.

METHODS

Streptozotocin-induced diabetic rats underwent side-to-side jejunoileal bypass plus proximal loop ligation (SSJIBL), end-to-side jejunoileal bypass (ESJIB), proximal small bowel resection (PBR), and sham operation. Each operational manner included two subgroups, in which 30 cm (L-30) or 40 cm (L-40) distal small bowel was retained. Main outcome measures were fasting blood glucose levels (FBG), insulin sensitivity, serum insulin, glucagon-like peptide-1 (GLP-1), bilirubin (BIL), and total bile acids (TBA) levels.

RESULTS

Global food intake in the sham group was higher than in the operation groups, and global body weight and food intake in the SSJIBL group were higher than in the ESJIB and PBR groups. Global body weight and food intake in L-40 group were higher than in L-30 group. The SSJIBL procedure induced better improvement in glucose homeostasis and insulin sensitivity than the ESJIB and PBR procedures, and L-30 group showed better antidiabetic effects than L-40 group. Serum GLP-1, BIL, and TBA levels in SSJIBL group were higher than in ESJIB and PBR groups.

CONCLUSIONS

This study shows that side-to-side jejunoileal bypass induced better glucose-lowering effects than end-to-side jejunoileal bypass and proximal small bowel resection, and intestinal bypass surgery that retained shorter distal small bowel yielded better antidiabetic effects.

Detailed characterization of incretin cell distribution along the human small intestine

BACKGROUND

Incretin hormones, glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide 1 (GLP-1), are physiologic stimulants of insulin release that have been implicated in diabetes remission after bariatric surgery. The detailed distribution of incretin cells along the human small gut, so far unknown, is of utmost importance for the understanding of the metabolic changes observed after bariatric surgery because diabetes remission rate varies according to the type of anatomic rearrangement.

OBJECTIVE

To characterize the distribution of incretin producing cells along the human jejunum-ileum.

SETTING

Academic public institution.

METHODS

Small intestines (n = 30) from autopsies were sampled every 20 cm along their entire length and tissue microarrays were constructed. The percentage of immunohistochemistry-stained cell areas for GLP-1, GIP, and chromogranin A at each segment length was quantified using a computer-aided analysis tool.

RESULTS

The percentage of stained area for GLP-1 immunoreactive cells was found to be significantly higher from 200 cm from Treitz ligament onward compared with the first 80 cm of the small intestine, whereas GIP immunoreactive cells were predominant expressed in the first 80 cm. In contrast, chromogranin A expression was constant along the entire jejunum-ileum.

CONCLUSION

The uneven distribution of GLP-1-expressing cells, with a higher density from 200 cm of the jejunum-ileum, could contribute to explain the improvement of glycemic profile of diabetic patients observed after anatomic rearrangement of the intestinal tract, in particular when subjected to gastric bypass with longer biliopancreatic limbs.

Bile acids, obesity, and the metabolic syndrome

Bile acids are increasingly recognized as key regulators of systemic metabolism. While bile acids have long been known to play important and direct roles in nutrient absorption, bile acids also serve as signalling molecules. Bile acid interactions with the nuclear hormone receptor farnesoid X receptor (FXR) and the membrane receptor G-protein-coupled bile acid receptor 5 (TGR5) can regulate incretin hormone and fibroblast growth factor 19 (FGF19) secretion, cholesterol metabolism, and systemic energy expenditure. Bile acid levels and distribution are altered in type 2 diabetes and increased following bariatric procedures, in parallel with reduced body weight and improved insulin sensitivity and glycaemic control. Thus, modulation of bile acid levels and signalling, using bile acid binding resins, TGR5 agonists, and FXR agonists, may serve as a potent therapeutic approach for the treatment of obesity, type 2 diabetes, and other components of the metabolic syndrome in humans.