Calcitonin gene-related peptide: neuroendocrine communication between the pancreas, gut, and brain in regulation of blood glucose

Role of TRP Channels in Metabolism-Related Diseases

Metabolic syndrome (MetS), with its high prevalence and significant impact on cardiovascular disease, poses a substantial threat to human health. The early identification of pathological abnormalities related to MetS and prevention of the risk of associated diseases is of paramount importance. Transient Receptor Potential (TRP) channels, a type of nonselective cation channel, are expressed in a variety of tissues and have been implicated in the onset and progression of numerous metabolism-related diseases. This study aims to review and discuss the expression and function of TRP channels in metabolism-related tissues and blood vessels, and to elucidate the interactions and mechanisms between TRP channels and metabolism-related diseases. A comprehensive literature search was conducted using keywords such as TRP channels, metabolic syndrome, pancreas, liver, oxidative stress, diabetes, hypertension, and atherosclerosis across various academic databases including PubMed, Google Scholar, Elsevier, Web of Science, and CNKI. Our review of the current research suggests that TRP channels may be involved in the development of metabolism-related diseases by regulating insulin secretion and release, lipid metabolism, vascular functional activity, oxidative stress, and inflammatory response. TRP channels, as nonselective cation channels, play pivotal roles in sensing various intra- and extracellular stimuli and regulating ion homeostasis by osmosis. They present potential new targets for the diagnosis or treatment of metabolism-related diseases.

Intra-pancreatic fat deposition across the pancreatitis spectrum and the influence of gut hormones

BACKGROUND AND AIMS

Acute pancreatitis (AP) and chronic pancreatitis (CP) often represent parts of the spectrum of disease. While growing evidence indicates that intra-pancreatic fat deposition (IPFD) plays an important role in the pathogenesis of pancreatitis, no study of living individuals has investigated IPFD in both AP and CP. Further, the associations between IPFD and gut hormones remain to be elucidated. The aims were to investigate the associations of IPFD with AP, CP, and health; and to study whether gut hormones affect these associations.

METHODS

Magnetic resonance imaging on the same 3.0 Tesla scanner was used to determine IPFD in 201 study participants. These participants were arranged into the health, AP, and CP groups. Gut hormones (ghrelin, glucagon-like peptide-1, gastric inhibitory peptide, peptide YY, and oxyntomodulin) were measured in blood, both after an 8-hour overnight fasting and after ingestion of a standardised mixed meal. A series of linear regression analyses was run, accounting for age, sex, ethnicity, body mass index, glycated haemoglobin, and triglycerides.

RESULTS

Both the AP group and CP group had significantly higher IPFD in comparison with the health group, consistently across all models (p for trend 0.027 in the most adjusted model). Ghrelin in the fasted state had a significant positive association with IPFD in the AP group (but not the CP or health group), consistently across all models (p = 0.019 in the most adjusted model). None of the studied gut hormones in the postprandial state was significantly associated with IPFD.

CONCLUSION

Fat deposition in the pancreas is similarly high in individuals with AP and those with CP. The gut-brain axis, and more specifically overexpression of ghrelin, may contribute to increased IPFD in individuals with AP.

Nutrition and Calcitonin Gene Related Peptide (CGRP) in Migraine

Targeting calcitonin gene-related peptide (CGRP) and its receptor by antibodies and antagonists was a breakthrough in migraine prevention and treatment. However, not all migraine patients respond to CGRP-based therapy and a fraction of those who respond complain of aliments mainly in the gastrointestinal tract. In addition, CGRP and migraine are associated with obesity and metabolic diseases, including diabetes. Therefore, CGRP may play an important role in the functioning of the gut-brain-microflora axis. CGRP secretion may be modulated by dietary compounds associated with the disruption of calcium signaling and upregulation of mitogen-activated kinase phosphatases 1 and 3. CGRP may display anorexigenic properties through induction of anorexigenic neuropeptides, such as cholecystokinin and/or inhibit orexigenic neuropeptides, such as neuropeptide Y and melanin-concentrating hormone CH, resulting in the suppression of food intake, functionally coupled to the activation of the hypothalamic 3',5'-cyclic adenosine monophosphate. The anorexigenic action of CGRP observed in animal studies may reflect its general potential to control appetite/satiety or general food intake. Therefore, dietary nutrients may modulate CGRP, and CGRP may modulate their intake. Therefore, anti-CGRP therapy should consider this mutual dependence to increase the efficacy of the therapy and reduce its unwanted side effects. This narrative review presents information on molecular aspects of the interaction between dietary nutrients and CGRP and their reported and prospective use to improve anti-CGRP therapy in migraine.

Intra-pancreatic fat deposition: bringing hidden fat to the fore

Development of advanced modalities for detection of fat within the pancreas has transformed understanding of the role of intra-pancreatic fat deposition (IPFD) in health and disease. There is now strong evidence for the presence of minimal (but not negligible) IPFD in healthy human pancreas. Diffuse excess IPFD, or fatty pancreas disease (FPD), is more frequent than type 2 diabetes mellitus (T2DM) (the most common disease of the endocrine pancreas) and acute pancreatitis (the most common disease of the exocrine pancreas) combined. FPD is not strictly a function of high BMI; it can result from the excess deposition of fat in the islets of Langerhans, acinar cells, inter-lobular stroma, acinar-to-adipocyte trans-differentiation or replacement of apoptotic acinar cells. This process leads to a wide array of diseases characterized by excess IPFD, including but not limited to acute pancreatitis, chronic pancreatitis, pancreatic cancer, T2DM, diabetes of the exocrine pancreas. There is ample evidence for FPD being potentially reversible. Weight loss-induced decrease of intra-pancreatic fat is tightly associated with remission of T2DM and its re-deposition with recurrence of the disease. Reversing FPD will open up opportunities for preventing or intercepting progression of major diseases of the exocrine pancreas in the future.

Hypoglycemic Effect of Electroacupuncture at ST25 Through Neural Regulation of the Pancreatic Intrinsic Nervous System

Electroacupuncture (EA) is considered to have potential antidiabetic effects; however, the role of the pancreatic intrinsic nervous system (PINS) in EA-induced amelioration of type 2 diabetes (T2DM) remains unclear. Therefore, we investigated whether EA at ST25 exerts any beneficial effects on insulin resistance (IR), inflammation severity, and pancreatic β cell function via the PINS in a rat model of a high-fat diet-streptozotocin (HFD/STZ)-induced diabetes. To this end, Sprague Dawley rats were fed with HFD to induce IR, followed by STZ (35 mg/kg, i.p.) injection to establish the T2DM model. After hyperglycemia was confirmed as fasting glucose level > 16.7 mmol/L, the rats were treated with EA (2 mA, 2/15 Hz) for the next 28 days. Model rats showed increased serum glucose, insulin, IR, and TNF-α levels with a concomitant decrease in β cell function. Microscopy examination of the pancreas revealed pathological changes in islets, which reverted to near-normal levels after EA at ST25. EA improved islet cell morphology by increasing islet area and reducing vacuolation. EA at ST25 decreased transient receptor potential vanilloid 1 (TRPV1) and increased substance P (SP) and calcitonin gene-related peptide (CGRP) expression. Subsequently, insulin secretion decreased and impaired pancreatic endocrine function was restored through the TRPV1 channel (SP/CGRP)-insulin circuit. EA increased choline acetyltransferase and neuropeptide Y expression and controlled inflammation. It also enhanced the cocaine and amphetamine-regulated transcript prepropeptide expression and promoted glucagon-like peptide-1 secretion. Additionally, the electrophysiological activity of PINS during acupuncture (2.71 ± 1.72 Hz) was significantly increased compared to the pre-acupuncture frequency (0.32 ± 0.37 Hz, P < 0.05). Thus, our study demonstrated the beneficial effect of EA on β cell dysfunction via the PINS in rat models of HFD-STZ-induced T2DM.

Oxyntomodulin may distinguish new-onset diabetes after acute pancreatitis from type 2 diabetes. Clin Transl Gastroenterol. 2020;11:e00132. [PMID: 32463621 PMCID: PMC7145025 DOI: 10.14309/ctg.0000000000000132]

OBJECTIVE

New-onset diabetes is an important sequela of acute pancreatitis, but there are no biomarkers to differentiate it from the much more common type 2 diabetes. The objective was to investigate whether postprandial circulating levels of gut hormones can serve this purpose.

METHODS

This was a case-control study nested into a prospective longitudinal cohort study that included 42 insulin-naive cases with new-onset prediabetes/diabetes after acute pancreatitis (NODAP) and prediabetes/diabetes followed by acute pancreatitis (T2D-AP), sex matched with 21 healthy controls. All individuals underwent a standardized mixed-meal test, and blood samples were assayed for gut hormones (glucose-dependent insulinotropic peptide, glucagon-like peptide-1, oxyntomodulin, and peptide YY). Analysis of variance and linear regression analysis were conducted in unadjusted and adjusted models (accounting for age, homeostatic model assessment of β-cell function, and magnetic resonance imaging-derived body fat composition).

RESULTS

Oxyntomodulin levels were significantly lower in NODAP compared with T2D-AP and healthy controls (P = 0.027 and P = 0.001, respectively, in the most adjusted model). Glucagon-like peptide-1 and peptide YY were significantly lower in NODAP compared with T2D-AP (P = 0.001 and P = 0.014, respectively, in the most adjusted model) but not compared with healthy controls (P = 1.000 and P = 0.265, respectively, in the most adjusted model). Glucose-dependent insulinotropic peptide levels were not significantly different between NODAP and T2D-AP.

DISCUSSION

Oxyntomodulin is a promising biomarker to guide the differential diagnosis of new-onset diabetes after acute pancreatitis. However, external validation studies are warranted before it can be recommended for routine use in clinical practice.

Effects of CGRP receptor antagonism on glucose and bone metabolism in mice with diet-induced obesity

The neuropeptide calcitonin gene-related peptide (CGRP) and its receptor, calcitonin receptor-like receptor (CLR) complexing with receptor activity-modifiying protein 1 (RAMP1), have been shown to be crucially involved in the pathogenesis of migraine. However, CGRP also plays a pivotal role in regulating bone turnover and was suggested to contribute to the development of the metabolic syndrome. Therefore, our study was designed to characterize the effects of CGRP antagonism on bone and glucose metabolism in a murine model of diet-induced obesity (DIO). A subcutaneous pellet releasing the CGRP receptor antagonist BIBN 4096 (BIBN; olcegepant) was implanted in WT mice with DIO. Metabolic effects were assessed through body- and organ-weights, oral glucose tolerance (oGT), serum lipids, and gene-expression studies. Bone turnover was assessed through histomorphometry of non-decalcified bone sections and analyses of bone turnover markers in serum samples. BIBN treatment did not alter body weight gain or the levels of serum lipids including triacylglycerol and cholesterol during DIO. BIBN led to a moderate improvement of oGT which was accompanied by an increased expression of stearoyl-CoA desaturase in the liver. In skeletal tissue, BIBN treatment resulted in reduced bone volume. This was explained by decreased parameters of bone formation whereas bone resorption was not affected. Our results indicate that inhibition of CGRP signaling only moderately affects glucose metabolism during DIO but significantly impairs bone formation. As novel agents blocking CGRP or its receptor are currently introduced clinically for the treatment of migraine disorders, their potential negative impact on bone metabolism requires further clinical studies.

Panorama of mediators in postpancreatitis diabetes mellitus

PURPOSE OF REVIEW

To provide an overview of mediators involved in the pathogenesis of postacute pancreatitis diabetes mellitus.

RECENT FINDINGS

The 'holistic prevention of pancreatitis' framework has brought to the fore the sequelae of not only end-stage chronic pancreatitis and extensive pancreatic necrosis but also mild acute pancreatitis. Insights from the DORADO project have provided a wealth of information on the signalling molecules that do and do not affect glucose metabolism in individuals after mild acute pancreatitis and have challenged conventional views of the pathogenesis of postpancreatitis diabetes mellitus.

SUMMARY

Growing evidence compels a reconsideration of the dogma that mechanical β-cell destruction (and the resulting insulin deficiency) is the only underlying mechanism of postpancreatitis diabetes mellitus. Chronic low-grade inflammation, β-cell compensation, lipolysis, altered secretion of gut hormones, and changes in iron metabolism characterize postacute pancreatitis diabetes mellitus. Some of these are druggable targets that offer novel opportunities to reduce the burden of pancreatitis through tertiary prevention.

Antidiabetic Medications and Mortality Risk in Individuals With Pancreatic Cancer-Related Diabetes and Postpancreatitis Diabetes: A Nationwide Cohort Study

OBJECTIVE

There are no specific treatment guidelines for diabetes of the exocrine pancreas. High-quality studies are warranted to investigate whether the use of antidiabetic medications has survival benefit in individuals with diabetes of the exocrine pancreas. The objective was to determine the risk of mortality associated with the use of antidiabetic medications in individuals with pancreatic cancer-related diabetes (PCRD) and postpancreatitis diabetes mellitus (PPDM).

RESEARCH DESIGN AND METHODS

Nationwide pharmaceutical dispensing data (2006-2015) linked to hospital discharge data were used to identify 1,862 individuals with PCRD or PPDM. Multivariable Cox regression analysis was conducted, and the risk was expressed as hazard ratios and 95% CIs. A 6-month lag was used to minimize reverse causality.

RESULTS

In individuals with PCRD, ever users of metformin (adjusted hazard ratio 0.54; 95% CI 0.46-0.63) and ever users of insulin (adjusted hazard ratio 0.46; 95% CI 0.39-0.55) had significantly lower risks of mortality compared with never users of antidiabetic medications. These associations attenuated toward the null with the use of a 6-month lag. In individuals with PPDM, ever users of metformin had a significantly lower risk of mortality (adjusted hazard ratio 0.51; 95% CI 0.36-0.70), whereas ever-users of insulin did not have a significantly changed risk of mortality (adjusted hazard ratio 0.75; 95% CI 0.49-1.14) compared with never users of antidiabetic medications. The former association remained significant with the use of a 6-month lag.

CONCLUSIONS

Metformin promotes a survival benefit in individuals with PPDM but not PCRD. Reverse causality may play a role in the association between insulin use and mortality in PCRD.

Global epidemiology and holistic prevention of pancreatitis

Knowledge of pancreatitis in the 20th century was shaped predominantly by animal data and clinical trials. Several large general population-based cohort studies and comprehensive systematic literature reviews in the 21st century have had a major effect on our understanding of pancreatitis and its sequelae. This Review provides precise and up-to-date data on the burden of acute pancreatitis, chronic pancreatitis and post-pancreatitis diabetes mellitus. Exocrine pancreatic insufficiency and altered bone metabolism following pancreatitis are also discussed. Furthermore, the article introduces a framework for the holistic prevention of pancreatitis with a view to providing guidance on strategies and intervention objectives at primary, secondary and tertiary levels. Concerted efforts by not only gastroenterologists and surgeons but also primary care physicians, endocrinologists, radiologists, pain specialists, dietitians, epidemiologists and public health specialists will be required to reduce meaningfully the burden of pancreatitis and its sequelae over the ensuing decades.

Development of Diabetes after Pancreaticoduodenectomy: Results of a 10-Year Series Using Prospective Endocrine Evaluation

BACKGROUND

Limited literature is available on the development of impaired glucose tolerance and diabetes mellitus after pancreaticoduodenectomy. The primary aim was to define the diabetic phenotype and correlate preoperative glycemic laboratory results to new-onset diabetes after pancreaticoduodenectomy.

STUDY DESIGN

In this prospective study, perioperative fasting and postprandial (oral glucose tolerance test) plasma glucose, glycated hemoglobin, insulin, and c-peptide were measured in consecutive patients undergoing pancreaticoduodenectomy by the senior author from 2006 to 2017. American Diabetes Association definitions were used for glycemic classifications. Multivariate risk factor analysis was performed.

RESULTS

Of 774 identified patients, 371 diabetics were excluded and 403 patients were included: 167 and 236 were preoperatively classified as nondiabetic and prediabetic, respectively. The incidence rates of diabetes at 120 months post pancreaticoduodenectomy were 9.0% (nondiabetics), 22.0% (prediabetics), and 16.6% (overall). Patients in whom diabetes developed demonstrated a 3-fold larger difference between oral glucose tolerance test and fasting glucose (Δ), and 2-fold larger Δinsulin and Δc-peptide values. Tiered multivariate analysis identified glycated hemoglobin >5.4% with a relative risk (RR) of 2.944 (p = 0.047) as an independent predictor of impaired glucose tolerance and diabetes mellitus. Analysis of patients stratified by preoperative classification identified fasting glucose >95 mg/dL (nondiabetics, RR 1.925; p = 0.002), and glycated hemoglobin ≥5.4% (prediabetics, RR 3.125; p = 0.040) as independent risk factors for diabetes. Compared with nondiabetics, prediabetics classified by any laboratory results demonstrated an RR of 2.471 (p = 0.001) for diabetes developing postoperatively. There was no association between primary pathology, advancing age, or BMI and increased risk of diabetes development.

CONCLUSIONS

Diabetes will develop after pancreaticoduodenectomy in approximately 16.6% of patients. A preoperative glycated hemoglobin >5.4% independently predicts new-onset diabetes. Pre- and postoperative endocrine analysis remains paramount for proper patient risk stratification.

Pancreas volume in health and disease: a systematic review and meta-analysis

The pancreas plays a central role in metabolism and is involved in the pathogenesis of several diseases. Pancreas volume is a holistic quantitative measure of pancreas size but the clinical relevance of pancreas volumetry is poorly understood. Areas covered: The aim was to systematically review studies in adults that used computed tomography or magnetic resonance imaging to measure pancreas volume in health and disease, to determine normal pancreas volume range, and to quantify changes in pancreas volume that are associated with disease. Expert commentary: The normal pancreas volume range in adults is 71-83 cm³, with no statistically significant difference between men and women. Type 2 diabetes and type 1 diabetes are associated with a progressively reduced pancreas volume. Overweight and obesity are associated with a progressively increased pancreas volume. There is a paucity of studies on pancreas volume in the setting of diseases of the exocrine pancreas, which should become a research priority in the future.