The effects of Calorie restriction and Bariatric surgery on Circulating Proneurotensin levels

CONTEXT

Proneurotensin (pNT) is associated with obesity and T2D, but the effects of Roux-en-Y gastric bypass (RYGB) on postprandial pNT levels are not well studied.

OBJECTIVE

Assess effects of RYGB versus very low-energy diet (VLED) on pNT levels in response to mixed-meal tests (MMT), and long-term effects of RYGB on fasting pNT.Study participants: Cohort 1: Nine normoglycemic (NG) and ten T2D patients underwent MMT before and after VLED, immediately post-RYGB and six weeks post-RYGB. Cohort 2: Ten controls with normal weight and ten patients with obesity and T2D, who underwent RYGB or vertical sleeve gastrectomy (VSG), were subjected to MMTs and GIP infusions pre-surgery and three months post-surgery. GLP-1 infusions were performed in normal weight participants. Cohort 3: Fasting pNT was assessed pre-RYGB (n=161), two months post-RYGB (n=92) and 1-year post-RYGB (n=118) in NG and T2D patients. pNT levels were measured using ELISA.

RESULTS

Reduced fasting and postprandial pNT were evident after VLED and immediately following RYGB. Reintroduction of solid food post-RYGB increased fasting and postprandial pNT. Prior to RYGB, all patients lacked a meal response in pNT, but this was evident post-RYGB/VSG. GIP- or GLP-1 infusion had no effect on pNT levels. Fasting pNT were higher 1-year post-RYGB regardless of glycemic status.

CONCLUSION

RYGB causes a transient reduction in pNT as a consequence of caloric restriction. The RYGB/VSG-induced rise in postprandial pNT is independent of GIP and GLP-1 and higher fasting pNT are maintained one year post-surgically.

RNA sequencing unravels novel L cell constituents and mechanisms of GLP-1 secretion in human gastric bypass-operated intestine

AIMS/HYPOTHESIS

Roux-en-Y gastric bypass surgery (RYGB) frequently results in remission of type 2 diabetes as well as exaggerated secretion of glucagon-like peptide-1 (GLP-1). Here, we assessed RYGB-induced transcriptomic alterations in the small intestine and investigated how they were related to the regulation of GLP-1 production and secretion in vitro and in vivo.

METHODS

Human jejunal samples taken perisurgically and 1 year post RYGB (n=13) were analysed by RNA-seq. Guided by bioinformatics analysis we targeted four genes involved in cholesterol biosynthesis, which we confirmed to be expressed in human L cells, for potential involvement in GLP-1 regulation using siRNAs in GLUTag and STC-1 cells. Gene expression analyses, GLP-1 secretion measurements, intracellular calcium imaging and RNA-seq were performed in vitro. OGTTs were performed in C57BL/6j and iScd1-/- mice and immunohistochemistry and gene expression analyses were performed ex vivo.

RESULTS

Gene Ontology (GO) analysis identified cholesterol biosynthesis as being most affected by RYGB. Silencing or chemical inhibition of stearoyl-CoA desaturase 1 (SCD1), a key enzyme in the synthesis of monounsaturated fatty acids, was found to reduce Gcg expression and secretion of GLP-1 by GLUTag and STC-1 cells. Scd1 knockdown also reduced intracellular Ca2+ signalling and membrane depolarisation. Furthermore, Scd1 mRNA expression was found to be regulated by NEFAs but not glucose. RNA-seq of SCD1 inhibitor-treated GLUTag cells identified altered expression of genes implicated in ATP generation and glycolysis. Finally, gene expression and immunohistochemical analysis of the jejunum of the intestine-specific Scd1 knockout mouse model, iScd1-/-, revealed a twofold higher L cell density and a twofold increase in Gcg mRNA expression.

CONCLUSIONS/INTERPRETATION

RYGB caused robust alterations in the jejunal transcriptome, with genes involved in cholesterol biosynthesis being most affected. Our data highlight SCD as an RYGB-regulated L cell constituent that regulates the production and secretion of GLP-1.

A New Beginning: Young Women's Experiences and Sexual Function 18 Months After Bariatric Surgery

Introduction

Female patients expect improved quality of life, including sexual health and regain of fertility after bariatric surgery. Little has been published on to the extent to which patients’ expectations are met by the weight loss after surgery.

Aim

To explore how women perceive the effects of bariatric surgery on quality of life, focusing on sexual health and fertility.

Methods

A qualitative study based on thematic analysis, supported by questionnaire data. Interviews following a semistructured guide were conducted with childless women (n = 11) aged 25–34 years recruited from a university-affiliated Swedish bariatric center. The interviews took place 18 months after surgery in the participants’ homes or at the hospital and were recorded and transcribed verbatim. Data were analyzed with a thematic approach. Questionnaires were filled in at the time of the interviews and compared with preoperative data using a Wilcoxon test for paired data.

Main outcome measures

Participants described experiences related to female sexual health after bariatric surgery. The Hospital Anxiety and Depression Scale and the Female Sexual Function Index questionnaires were administered preoperatively and postoperatively.

Results

“A new beginning” was identified as the master theme, with 3 underlying subthemes: “Being worthy of love,” “Exploring sexuality,” and “Considering parenthood.” The participants described a transformation into being more comfortable with themselves that affected all areas of life, including sexual life. These findings were supported by lower scores for depression, 6.5 vs 2, and improved total Female Sexual Function Index scores, median 23.3 preoperatively and 29.1 postoperatively, P = .012.

Conclusions

Improved body image and enhanced self-esteem play important roles in improved sexual functioning in women after bariatric surgery.

Nilsson-Condori E, Järvholm S, Thurin-Kjellberg A, et al. A New Beginning: Young Women’s Experiences and Sexual Function 18 Months After Bariatric Surgery. Sex Med 2020;8:730–739.

Metabolic Effects of Gastric Bypass Surgery: Is It All About Calories?

Bariatric surgery is an efficient method to induce weight loss and also, frequently, remission of type 2 diabetes (T2D). Unpaired studies have shown bariatric surgery and dietary interventions to differentially affect multiple hormonal and metabolic parameters, suggesting that bariatric surgery causes T2D remission at least partially via unique mechanisms. In the current study, plasma metabolite profiling was conducted in patients with (n = 10) and without T2D (n = 9) subjected to Roux-en-Y gastric bypass surgery (RYGB). Mixed-meal tests were conducted at baseline, after the presurgical very-low-calorie diet (VLCD) intervention, immediately after RYGB, and after a 6-week recovery period. Thereby, we could compare fasted and postprandial metabolic consequences of RYGB and VLCD in the same patients. VLCD yielded a pronounced increase in fasting acylcarnitine levels, whereas RYGB, both immediately and after a recovery period, resulted in a smaller but opposite effect. Furthermore, we observed profound changes in lipid metabolism following VLCD but not in response to RYGB. Most changes previously associated with RYGB were found to be consequences of the presurgical dietary intervention. Overall, our results question previous findings of unique metabolic effects of RYGB and suggest that the effect of RYGB on the metabolite profile is mainly attributed to caloric restriction.

Ghrelin suppresses insulin secretion in human islets and type 2 diabetes patients have diminished islet ghrelin cell number and lower plasma ghrelin levels

It is not known how ghrelin affects insulin secretion in human islets from patients with type 2 diabetes (T2D) or whether islet ghrelin expression or circulating ghrelin levels are altered in T2D. Here we sought out to identify the effect of ghrelin on insulin secretion in human islets and the impact of T2D on circulating ghrelin levels and on islet ghrelin cells. The effect of ghrelin on insulin secretion was assessed in human T2D and non-T2D islets. Ghrelin expression was assessed with RNA-sequencing (n = 191) and immunohistochemistry (n = 21). Plasma ghrelin was measured with ELISA in 40 T2D and 40 non-T2D subjects. Ghrelin exerted a glucose-dependent insulin-suppressing effect in islets from both T2D and non-T2D donors. Compared with non-T2D donors, T2D donors had reduced ghrelin mRNA expression and 75% less islet ghrelin cells, and ghrelin mRNA expression correlated negatively with HbA1c. T2D subjects had 25% lower fasting plasma ghrelin levels than matched controls. Thus, ghrelin has direct insulin-suppressing effects in human islets and T2D patients have lower fasting ghrelin levels, likely as a result of reduced number of islet ghrelin cells. These findings support inhibition of ghrelin signaling as a potential therapeutic avenue for stimulation of insulin secretion in T2D patients.

Gastric bypass in the pig increases GIP levels and decreases active GLP-1 levels

Gastric bypass surgery results in remission of type 2 diabetes in the majority of patients. The incretin hormones glucagon-like peptide 1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP) have been implicated in the observed remission. Most knowledge so far has been generated in obese subjects. To isolate the surgical effects of gastric bypass on metabolism and hormone responses from the confounding influence of obesity, T2D, or food intake, we performed gastric bypass in lean pigs, using sham-operated and pair-fed pigs as controls. Thus, pigs were subjected to Roux-en-Y gastric bypass (RYGB) or sham surgery and oral glucose tolerance tests (OGTT). RYGB pigs and sham pigs exhibited similar basal and 120-min glucose levels in response to the OGTT. However, RYGB pigs had approximately 1.6-fold higher 30-min glucose (p<0.01). Early insulin release (EIR) was enhanced approximately 3.5-fold in the RYGB pigs (p<0.01). Furthermore, GIP release, both acute and sustained release (p<0.001 and p<0.01, respectively), was increased approximately 2.5-fold and 1.4-fold, respectively, in RYGB pigs. Although total GLP-1 release increased approximately 2.1-fold after RYGB (p<0.001), active GLP-1 was 33% lower (p<0.01). Interestingly basal DPP4-activity was approximately 3.2-fold higher in RYGB pigs (p<0.001). In conclusion, RYGB in lean pigs increases the response of GIP, total GLP-1, and insulin, but reduces levels of active GLP-1 in response to an oral glucose load. These data challenge the role of active GLP-1 as a contributor to remission from diabetes after RYGB.

The impact of Roux-en-Y gastric bypass surgery on normal metabolism in a porcine model

BACKGROUND

A growing body of literature on Roux-en-Y gastric bypass surgery (RYGB) has generated inconclusive results on the mechanism underlying the beneficial effects on weight loss and glycaemia, partially due to the problems of designing clinical studies with the appropriate controls. Moreover, RYGB is only performed in obese individuals, in whom metabolism is perturbed and not completely understood.

METHODS

In an attempt to isolate the effects of RYGB and its effects on normal metabolism, we investigated the effect of RYGB in lean pigs, using sham-operated pair-fed pigs as controls. Two weeks post-surgery, pigs were subjected to an intravenous glucose tolerance test (IVGTT) and circulating metabolites, hormones and lipids measured. Bile acid composition was profiled after extraction from blood, faeces and the gallbladder.

RESULTS

A similar weight development in both groups of pigs validated our experimental model. Despite similar changes in fasting insulin, RYGB-pigs had lower fasting glucose levels. During an IVGTT RYGB-pigs had higher insulin and lower glucose levels. VLDL and IDL were lower in RYGB- than in sham-pigs. RYGB-pigs had increased levels of most amino acids, including branched-chain amino acids, but these were more efficiently suppressed by glucose. Levels of bile acids in the gallbladder were higher, whereas plasma and faecal bile acid levels were lower in RYGB- than in sham-pigs.

CONCLUSION

In a lean model RYGB caused lower plasma lipid and bile acid levels, which were compensated for by increased plasma amino acids, suggesting a switch from lipid to protein metabolism during fasting in the immediate postoperative period.

The mesenteric defects in laparoscopic Roux-en-Y gastric bypass: 5 years follow-up of non-closure versus closure using the stapler technique

BACKGROUND

Internal hernia (IH) is a common complication of laparoscopic Roux-en-Y gastric bypass (LRYGB). Little large-volume data exist on how to handle the mesenteric defects during LRYGB. This study evaluated long-term follow-up (5.5 years) of 2443 patients with primary closure of the mesenteric defects with a stapling device at LRYGB, in comparison with a non-closed group from the same centre.

METHODS

All patients (N = 4013) undergoing LRYGB over a 10-year period (2005-2015) at a single institution were evaluated. The mesenteric defects were routinely closed starting June 2010. In total, 1570 non-closure patients and 2443 patients with stapled closure of the defects were prospectively entered and the results analysed.

RESULTS

Closure of the mesenteric defects increased surgical time by 4 min and did not affect the 30-day complication rate. IH incidence was significantly lower (2.5%) in the closure group compared with 11.7% in the non-closure group, at 60 months. The relative risk reduction by closing the mesenteric defects was 4.09-fold (95% CI = 2.97-5.62) as calculated using a survival model.

CONCLUSIONS

Internal hernia after LRYGB occurs frequently if mesenteric defects are left unclosed. Primary closure with a hernia-stapling device is safe and significantly reduces the risk of internal hernia.

Clinical Indications, Utilization, and Funding of Bariatric Surgery in Europe

Purpose

The objective of this study was to evaluate the current utilization, the level of endorsement by professional societies, and health technology assessment bodies, as well as the reimbursement levels for bariatric surgery in European countries.

Materials and Methods

We performed an analysis of the indications for bariatric surgery based on national clinical and commissioning guidelines, current utilization of surgery, characteristics of patients who underwent surgery, and reimbursement tariffs in Belgium, Denmark, England, France, Germany, Italy, and Sweden. Data were obtained from national patient registries, administrative databases, and published literature for the year 2012.

Results

Despite clear consensus outlined in clinical guidelines, significant differences were found in the eligibility criteria for surgery. Patients with no significant comorbidities were deemed eligible if they had a body mass index (BMI) of 40 or 50 kg/m² in Denmark. Irrespective of the country, patients with comorbidities were eligible if they had a BMI of 35 kg/m². The highest utilization of bariatric surgery (number of surgeries per 1 M population) was observed in Belgium (928), Sweden (761), and France (571) while Italy (128), England (117), and Germany (72) had the lowest utilization. There was a strong negative correlation between utilization and average BMI level of the patient population (r = −.909, p = 0.005). The annual per capita spending on surgery differed significantly between countries, ranging from €0.54 in Germany to €4.33 in Belgium.

Conclusions

There are significant variations in the clinical indications, utilization, and funding of bariatric surgery in European countries.

Electronic supplementary material

The online version of this article (doi:10.1007/s11695-014-1537-y) contains supplementary material, which is available to authorized users.

Bariatric Surgery can Lead to Net Cost Savings to Health Care Systems: Results from a Comprehensive European Decision Analytic Model

BACKGROUND

The objective of the present study was to evaluate the cost-utility of bariatric surgery in a lifetime horizon from a Swedish health care payer perspective.

METHODS

A decision analytic model using the Markov process was developed covering cardiovascular diseases, type 2 diabetes, and surgical complications. Clinical effectiveness and safety were based on the literature and data from the Scandinavian Obesity Surgery Registry. Gastric bypass, sleeve gastrectomy, and gastric banding were included in the analysis. Cost data were obtained from Swedish sources.

RESULTS

Bariatric surgery was cost saving in comparison with conservative management. It also led to a substantial reduction in lifetime risk of events: from a 16 % reduction in the risk of transient ischaemic attacks to a 62 % reduction in the incidence of type 2 diabetes. Over a lifetime, surgery led to savings of euro 8408 and generated an additional 0.8 years of life and 4.1 quality-adjusted life years (QALYs) per patient, which translates into gains of 32,390 quality-adjusted person-years and savings of euro 66 million for the cohort, operated in 2012. Analysis of the consequences of a 3-year delay in surgery provision showed that the overall lifetime cost of treatment may be increased in patients with diabetes or a body mass index >40 kg/m(2). Delays in surgery may also lead to a loss of clinical benefits: up to 0.6 life years and 1.2 QALYs per patient over a lifetime.

CONCLUSION

Bariatric surgery, over a lifetime horizon, may lead to significant cost savings to health care systems in addition to the known clinical benefits.

Gastric bypass with long alimentary limb or long pancreato-biliary limb--long-term results on weight loss, resolution of co-morbidities and metabolic parameters

Background

Several studies indicate that increasing the alimentary limb length in gastric bypass surgery produces only a minor improvement of excess BMI loss. Few studies have addressed the efficacy of increasing the length of the pancreatico-biliary limb.

Methods

Here, we present a prospective randomized study of 187 consecutive laparoscopic Roux-Y gastric bypass operations operated over 2 years (2004–2005) in Iceland. The patients were operated with a gastric bypass with either a 2-m biliopancreatic (BP)-limb and a 60-cm alimentary (A)-limb (n = 93) or with a 150-cm A-limb and a 60-cm BP-limb (n = 94).

Results

Preoperative median BMI was 44.1 (38–70), median age 35.5 (17–74) years, and 85 % of the patients were female. Follow-up rate after 5 years was 85 %. Eighteen months following surgery, the weight loss was significantly higher in the BP-limb group (p < 0.001), and this difference remained 7 years after surgery. Weight regain occurred in both groups, and 7 years after surgery, excess BMI loss (EBMIL) was 78.4 % in the BP-limb group compared to 67.1 % in the A-limb group (p < 0.001). Most patients (78 %) needed supplementation adjustment (iron, vitamin D and calcium) during the study period, significantly more often in the BP-limb group compared to the A-limb group (p < 0.001). Patients in the BP-limb group had more frequent stools than patients in the A-limb group; otherwise, gastro-intestinal symptoms rating scoring were comparable. Complication rate was similar.

Conclusions

Gastric bypass with a 2-m BP-limb gives better weight loss than gastric bypass with a 60-cm BP-limb and a 150-cm A-limb. Metabolic follow-up is of utmost importance, as most patients needed repeated adjustments of their supplementation.

Gastric bypass improves β-cell function and increases β-cell mass in a porcine model

The most frequently used and effective treatment for morbid obesity is Roux-en-Y gastric bypass surgery (RYGB), which results in rapid remission of type 2 diabetes in most cases. To what extent this is accounted for by weight loss or other factors remains elusive. To gain insight into these mechanisms, we investigated the effects of RYGB on β-cell function and β-cell mass in the pig, a species highly reminiscent of the human. RYGB was performed using linear staplers during open surgery. Sham-operated pigs were used as controls. Both groups were fed a low-calorie diet for 3 weeks after surgery. Intravenous glucose tolerance tests were performed 2 weeks after surgery. Body weight in RYGB pigs and sham-operated, pair-fed control pigs developed similarly. RYGB pigs displayed improved glycemic control, which was attributed to increases in β-cell mass, islet number, and number of extraislet β-cells. Pancreatic expression of insulin and glucagon was elevated, and cells expressing the glucagon-like peptide 1 receptor were more abundant in RYGB pigs. Our data from a pig model of RYGB emphasize the key role of improved β-cell function and β-cell mass to explain the improved glucose tolerance after RYGB as food intake and body weight remained identical.

Management of suspected anastomotic leak after bariatric laparoscopic Roux-en-y gastric bypass

Background

Anastomotic leak is one of the most serious complications following bariatric laparoscopic Roux-en-Y gastric bypass (LRYGB), and associated with high morbidity rates and prolonged hospital stay. Timely management is of utmost importance for the clinical outcome. This study evaluated the approach to suspected leakage in a high-volume bariatric surgery unit.

Methods

All consecutive patients who underwent LRYGB performed by the same team of surgeons were registered prospectively in a clinical database from September 2005 to June 2012. Suspected leaks were identified based on either clinical suspicion and/or associated laboratory values, or by a complication severity grade of at least II using the Clavien–Dindo score.

Results

A total of 6030 patients underwent LRYGB during the study period. The leakage rate was 1·1 per cent (64 patients). Forty-five leaks (70 per cent) were treated surgically and 19 (30 per cent) conservatively. Eight (13 per cent) of 64 patients needed intensive care and the mortality rate was 3 per cent (2 of 64). Early leaks (developing in 5 days or fewer after LRYGB) were treated by suture of the defect in 20 of 22 patients and/or operative drainage in 13. Late leaks (after 5 days) were managed with operative drainage in 19 of 23 patients and insertion of a gastrostomy tube in 15. Patients who underwent surgical treatment early after the symptoms of leakage developed had a shorter hospital stay than those who had symptoms for more than 24 h before reoperation (12·5 versus 24·4 days respectively; P < 0·001).

Conclusion

Clinical suspicion of an anastomotic leak should prompt an aggressive surgical approach without undue delay. Early operative treatment was associated with shorter hospital stay. Delays in treatment, including patient delay, after symptom development were associated with adverse outcomes.

Effects of ingestion routes on hormonal and metabolic profiles in gastric-bypassed humans

CONTEXT

Gastric bypass surgery (GBP) results in the rapid resolution of type 2 diabetes. Most studies aiming to explain the underlying mechanisms are limited to data obtained after a postsurgical recovery period, making assessment of confounding influences from, for example, weight loss and altered nutrient intake difficult.

OBJECTIVE

To examine the impact of GBP on hormonal and metabolite profiles under conditions of identical nutrient intake independent of weight loss, we studied GBP patients fitted with a gastrostomy tube to enable the administration of nutrients to bypassed segments of the gut. Thus, this model allowed us to simulate partially the preoperative condition and compare this with the postoperative situation in the same patient.

DESIGN

Patients (n = 4) were first given a mixed meal test (MMT) orally and then via the gastrostomy tube, preceded by overnight and 2-hour fasting, respectively. Blood samples were assessed for hormones and metabolites.

RESULTS

The oral MMT yielded 4.6-fold increase in plasma insulin (P < .05), 2-fold in glucagon-like peptide-1 (P < .05), and 2.5-fold in glucose-dependent insulinotropic peptide (P < .05) plasma levels, compared with the gastrostomy MMT. The changes in hormone levels were accompanied by elevated branched-chain amino acid levels (1.4-2-fold, P < .05) and suppressed fatty acid levels (∼50%, P < .05).

CONCLUSIONS

These data, comparing identical nutrient delivery, demonstrate markedly higher incretin and insulin responses after oral MMT than after gastric MMT, thereby providing a potential explanation for the rapid remission of type 2 diabetes observed after GBP. The simultaneous increase in branched-chain amino acid questions its role as a marker for insulin resistance.

Variation in the adiponutrin gene influences its expression and associates with obesity

Adiponutrin is one of three recently identified adipocyte lipases. Surprisingly, these proteins also retain transacylase activity, a hitherto unknown pathway of triacylglycerol synthesis in the adipocytes. This may enable them to participate in both anabolic and catabolic processes. The adiponutrin gene (ADPN) is downregulated by fasting and upregulated by refeeding, suggesting a role in lipogenesis. Experiments in human adipocytes confirmed that the gene is upregulated in response to insulin in a glucose-dependent fashion. Obese subjects had increased levels of subcutaneous and visceral abdominal adipose tissue ADPN mRNA. Visceral ADPN mRNA expression was correlated to measures of insulin sensitivity (fasting insulin and homeostasis model assessment). We also studied genetic variation in ADPN and its relation to obesity, lipolysis, and mRNA expression. Two ADPN polymorphisms showed association with obesity. Carriers of the obesity-associated variants showed a lesser increase in the levels of adipose tissue ADPN mRNA and an increased basal lipolysis. Our results suggest that obese subjects that are insulin resistant and/or carriers of the obesity-associated ADPN alleles fail to upregulate the gene and that upregulation of adiponutrin may be an appropriate response to orchestrate energy excess.

Effects of pH on Helicobacter pylori binding to human gastric mucins: identification of binding to non-MUC5AC mucins

Helicobacter pylori causes gastritis, peptic ulcer disease and gastric cancer. The microbe is found in the gastric mucus layer where a pH gradient ranging from acidic in the lumen to neutral at the cell surface is maintained. The aim of the present study was to investigate the effects of pH on H. pylori binding to gastric mucins from healthy individuals. At pH 3, all strains bound to the most charged MUC5AC glycoform and to a putative mucin of higher charge and larger size than subunits of MUC5AC and MUC6, irrespective of host blood-group. In contrast, at pH 7.4 only Le(b)-binding BabA-positive strains bound to Le(b)-positive MUC5AC and to smaller mucin-like molecules, including MUC1. H. pylori binding to the latter component(s) seems to occur via the H-type-1 structure. All strains bound to a proteoglycan containing chondroitin sulphate/dermatan sulphate side chains at acidic pH, whereas binding to secreted MUC5AC and putative membrane-bound strains occurred both at neutral and acidic pH. The binding properties at acidic pH are thus common to all H. pylori strains, whereas mucin binding at neutral pH occurs via the bacterial BabA adhesin and the Le(b) antigen/related structures on the glycoprotein. Our work shows that microbe binding to membrane-bound mucins must be considered in H. pylori colonization, and the potential of these glycoproteins to participate in signalling events implies that microbe binding to such structures may initiate signal transduction over the epithelial layer. Competition between microbe binding to membrane-bound and secreted mucins is therefore an important aspect of host-microbe interaction.

Pro-opiomelanocortin gene is associated with serum leptin levels in lean but not in obese individuals

OBJECTIVE

Mutations in the pro-opiomelanocortin and melanocortin 4 receptor genes (POMC and MC4R) cause monogenic obesity, and the POMC locus (2p21) has been linked to leptin levels and body mass index (BMI). We searched for monogenic obesity due to mutations in POMC and MC4R among morbidly obese Swedes and studied the association of POMC variants with BMI and serum leptin levels.

DESIGN

MC4R and POMC were screened for mutations in 102 obese Swedish subjects (40+/-11 y, 41.3+/-5.0 kg/m(2)) using the single-strand conformation polymorphism technique. The detected polymorphisms were genotyped in 118 lean control subjects (56+/-11 y, 22.6+/-1.3 kg/m(2)) and studied for association with BMI and serum leptin levels.

RESULTS

No cases of monogenic obesity due to mutations in POMC or MC4R were identified and none of the four common POMC polymorphisms (RsaI, ins56, Glu188Gly and C8246T) were associated with obesity. Lean carriers of the C8246T CC-genotype had higher serum leptin levels compared to CT or TT carriers (9.7+/-6.6 vs 6.7+/-4.4 microg/l, P=0.003 for leptin levels adjusted for age, sex and BMI in regression analysis), especially lean females (P=0.004) and lean female carriers with the C8246T(CC)/RsaI(--or +-) genotype combinations (P<0.0005). Neither the C8246T CC-genotype nor the C8246T(CC)/RsaI(--or +-) were associated with serum leptin levels in obese subjects.

CONCLUSIONS

Monogenic forms of obesity due to mutations in POMC and MC4R are rare in Swedish obese patients. Polymorphisms in POMC are associated with variation in serum leptin levels within the normal range in healthy lean but not in obese individuals.

Strain- and blood group-dependent binding of Helicobacter pylori to human gastric MUC5AC glycoforms

BACKGROUND & AIMS

In the stomach, Helicobacter pylori is found both in the mucus layer and adhering to the gastric epithelium. The aim of this study is to characterize the binding of H. pylori to human gastric mucins.

METHODS

H. pylori strains that bind the Lewis(b) (Le(b)) structure (via the BabA adhesin) and/or sialylated structures, along with isogenic adhesion deletion mutants, were used to identify microbe-binding mucins. Gastric mucins from 5 healthy individuals, isolated by density-gradient centrifugation, were investigated for H. pylori binding at neutral pH using a microtiter-based technique.

RESULTS

H. pylori strains that express the BabA adhesins were shown to bind to the MUC5AC mucin in individuals expressing the Le(b) antigen. Further fractionation with an ion-exchange chromatography revealed Le(b)-positive MUC5AC glycoforms that differed in their receptor properties for different H. pylori strains. None of the H. pylori strains studied bound to mucins from Le(b)-negative individuals. However, all strains bound to low-density, nonmucin, Le(b)-negative material on top of the gradients.

CONCLUSIONS

Binding of H. pylori to human gastric MUC5AC isolated from healthy individuals is BabA dependent and mediated by the Le(b) structure presented by the mucin. However, the BabA adhesins demonstrate strain-dependent preference in binding to MUC5AC glycoforms substituted with Le(b), allowing for great interindividual variability in host-microbe interactions.

Energy expenditure during treadmill walking before and after vertical banded gastroplasty: a one-year follow-up study in 11 obese women

OBJECTIVE

To find out whether weight reduction induced by vertical banded gastroplasty (VBG) alters the energy expenditure in severely obese women during treadmill walking.

DESIGN

A prospective one year follow-up study, patients being their own controls.

SETTING

University hospital, Sweden.

SUBJECTS

A consecutive series of 11 women who had VBG.

MAIN OUTCOME MEASURES

Indirect calorimetry, body mass index (BMI), preset and comfortable walking speeds, heart rate, perceived exertion, and quality of life.

RESULTS

11 patients were evaluated. Mean BMI (kg/ml) decreased from 41 (range 36-46) before to 32 (range 25-37) 12 months postoperatively. The energy expenditure decreased significantly both at comfortable and preset walking speeds. The comfortable walking speed increased from 2.7 km x h(-1) (range 1.3-3.4) before operation to 3.8 (range 2.0-4.2) one year postoperatively (p = 0.003). All bodily variables in the SF-36 questionnaire showed improvement from 6 months onwards.

CONCLUSION

Weight reduction in women reduces the energy expenditure during walking both at comfortable and preset speeds. The comfortable walking speed is increased. The improvements are reflected in the patients' own assessment.

Common variants in the beta2-(Gln27Glu) and beta3-(Trp64Arg)--adrenoceptor genes are associated with elevated serum NEFA concentrations and type II diabetes

AIMS/HYPOTHESIS

Higher NEFA concentrations predict Type II (non-insulin-dependent) diabetes mellitus but it is not known whether higher NEFA concentrations are genetically determined or reflect coexisting obesity. To address this question we studied whether common variants in two genes encoding for key regulators of lipolysis, the beta2- and beta3- adrenoceptors (B2AR and B3AR) are associated with NEFA concentrations and Type II diabetes.

METHODS

A total of 1054 Swedish subjects with varying degrees of glucose tolerance were genotyped for the Gln27Glu variant in the B2AR and for the Trp64Arg variant in the B3AR genes using PCR-RFLP.

RESULTS

The B2AR Gln27 allele was more frequent in 219 Type II diabetic patients than in 237 non-diabetic subjects (59.8 % vs 52.3 %; OR = 1.72, p = 0.02) while there was no significant difference in the frequency of the B3AR Arg64 allele. Subjects homozygous for the protective alleles (Glu27 and Trp64) had, however, a lower prevalence of diabetes than subjects with other genotype combinations (OR = 0.58, p = 0.03). Among sibling pairs discordant for the B2AR Gln27Glu polymorphism, siblings with an excess of the Gln27 allele had higher fasting insulin (n = 217; p = 0.02) and NEFA concentrations (107 sex-matched pairs; p = 0.01) than siblings with an excess of the Glu27 allele. Among sibling pairs discordant for the B3AR Trp64Arg variant, siblings with the Arg64 allele had higher 2 h glucose (n = 48; p = 0.01) and NEFA concentrations (16 pairs matched for sex; p < 0.04) than siblings with the Trp64Trp64 genotype.

CONCLUSIONS/INTERPRETATION

Common variants in the beta2- and beta3- adrenoceptor genes are associated with increased fasting insulin and NEFA concentrations and could increase susceptibility to Type II diabetes.

The T 54 allele of the intestinal fatty acid-binding protein 2 is associated with a parental history of stroke

To test the hypothesis that the A/T polymorphism of the fatty acid-binding protein 2 gene (FABP2) is associated with impaired lipid metabolism and cardiovascular disease, we compared clinical characteristics and a parental history of cardiovascular disease between 213 sibling pairs discordant for the polymorphism. Siblings with an excess of the T54 allele had higher triglyceride (P = 0.002) and cholesterol (P = 0.019) concentrations than siblings with the A54 allele. Parents of offspring with the T54T and T54A genotypes reported an increased prevalence of stroke compared to parents of offspring with the A54A genotype (P = 0.007). In summary, we have confirmed the association of the FABP2 T54 allele with increased concentrations of cholesterol and triglycerides in genotype-discordant sibling pairs. We also present novel evidence that genetic variation in the FABP2 gene may increase susceptibility to stroke.

Neither low-calorie diet nor vertical banded gastroplasty influence gastro-oesophageal reflux in morbidly obese patients

OBJECTIVE

Investigate the effect of a liquid diet, and of vertical banded gastroplasty, on gastro-oesophageal reflux in morbidly obese patients.

DESIGN

Prospective study, patients being their own controls.

SETTING

University hospital, Sweden.

SUBJECTS

25 morbidly obese patients, listed for vertical banded gastroplasty.

INTERVENTIONS

24 hour ambulatory intra-oesophageal pH-monitoring three weeks before operation and repeated after 10-14 days on a liquid very low calorie diet, and finally three weeks after operation, while still on a liquid very low calorie diet.

MAIN OUTCOME MEASURES

Percentage of time that pH in the oesophagus was < or =4.

RESULTS

There were no changes in the amount of reflux, either after a liquid diet or after vertical banded gastroplasty.

CONCLUSIONS

Neither the liquid diet nor vertical banded gastroplasty alone had any appreciable effect on gastro-oesophageal reflux.

Weight Loss After Vertical Banded Gastroplasty Can Be Predicted: A Prospective Psychological Study

BACKGROUND: Although treatment failure after Vertical Banded Gastroplasty (VBG) is not uncommon, the safety of the procedure makes it the most widely used form of bariatric surgery. The reasons for failure may be either technical, such as staple-line dehiscence, or psychological inability on the part of the patient to adjust to the small stomach pouch and to its consequences. METHODS: We carried out prospective testing of a cohort of consecutive VBG candidates, using a battery of psychological tests consisting of the 'Three Factor Eating Questionnaire', 'Hopkins Symptom Check List (HSCL)', 'Mood Adjective Check List (MACL)', 'Karolinska Scales of Personality (KSP)', and two projective tests, the 'MetaContrast Technique (MCT)' and the 'Perceptgenetic Object Relation Test (PORT)'. The patients had been scheduled for surgery on clinical considerations only, and the results of the psychological testing were not disclosed to the surgeons until after the follow-up. RESULTS: Mean preoperative Body Mass Index (BMI) was 42.0 (SD 9.9). Patients were extensively tested during the 3 weeks prior to surgery. There were no operative complications. Patients were tested psychologically again after 3 years. Their mean BMI then was 32.3 (SD 6.6). Thirteen patients had lost more than 50% of their overweight (BMI mean 29.6; SD 1.1), seven patients had lost less than 50% (BMI mean 37.0; SD 1.6; p = 0.0043). These two groups were compared. The single factor that correlated consistently with an unsatisfactory weight loss was preoperative signs of depression (p = 0.04). Stepwise discriminant analysis using three preoperative factors (Hunger, Verbal aggression and Socialization) correctly classified 90% of the patients who had lost < 50% of their overweight. Other variables (impulsivity, Emotional detachment and Maladaptive psychological defense) identified patients who were later to suffer from dysphoric mood (n=5) or disturbed eating behavior (n=ll).These factors may compromise a sustained ability to tolerate food restriction. Despite the operation's disadvantages, all patients considered it worthwhile and displayed improved psychosocial adaptation post-operatively. CONCLUSION: We conclude that extensive psychological testing can accurately predict the intermediate-term weight outcome following VBG and that even patients who show little weight loss benefit from the procedure.

Preoperative Intermaxillary Fixation has no Influence on Weight Loss Induced by Vertical Banded Gastroplasty

Surgery is the only therapeutic modality that has shown lasting results in the treatment of morbid obesity. Ability to lose weight by voluntary dieting has been associated with unsatisfactory weight loss after gastroplasty. This report examines the effect of preoperative inter-maxillary fixation (IMF) on weight reduction induced by vertical banded gastroplasty (VBG). Twenty-four patients entered the study and were randomly assigned to either 10 weeks of IMF or 10 weeks on the waiting-list. Patient groups were similar in respect to age, gender and Body Mass Index (BMI). All patients were urged to lose weight preoperatively. Patients in the IMF group lost 18 kg (-12 to -36; median, range) and the waiting list group lost 3 kg (+ 3 to -30) during the 10 weeks prior to surgery. Total weight loss from time of inclusion to 24 months postoperatively was the same in both groups. Our results suggest that weight loss up to 2 years after VBG is not Influenced by short-term preoperative IMF. Although we found no obvious advantage in having patients pre-treated by IMF, our findings indicate that jaw wiring can be used for patients in whom moderate preoperative weight loss is desired without endangering the effect of VBG on body weight development.

Delta sleep-inducing peptide (DSIP)-like immunoreactivity in gut: coexistence with known peptide hormones

Delta sleep-inducing peptide-like immunoreactivity (DSIP-LI) has previously been demonstrated in brain neurons and in endocrine cells of the pituitary and the adrenal medulla. By means of three different antisera against synthetic DSIP we now describe the occurrence and distribution of DSIP-LI in several gut endocrine cells. The human gut was the richest source, where DSIP-LI was located in gastrin/CCK, secretin and PYY/glicentin cells. The rat and pig gut harbour a moderate number of immunoreactive cells in the antral mucosa but in the intestines DSIP-LI-containing cells were very few. By radioimmunoassay, the concentration of DSIP-LI was determined in extracts of various gut regions from man, pig and rat. The highest concentrations were found in all human specimens compared with corresponding samples in the pig and rat. In all three species, high-performance liquid chromatography revealed a single peak of DSIP-like material with approximately the same retention time as DSIP 3-9. Taken together, the present results provide evidence for the presence of DSIP-LI in gut endocrine cells in man, pig and rat; the human gut seems to be the richest source of DSIP-like peptides.

Endocrine cells and parietal cells in the stomach of the developing rat

Gastrin-immunoreactive cells were fairly numerous in the pancreas and upper duodenum of the rat at about the time of birth. A minor population of these cells stained with antibodies directed against the N-terminal region of gastrin-34 as well as with antibodies directed against the C-terminal region. The remainder of the cells stained with the C-terminally directed antibodies only. Within a fortnight after birth all gastrin-immunoreactive cells disappeared from the pancreas and were greatly reduced in number in the duodenum; those that remained were probably CCK cells. Gastrin cells were rare in the antrum at birth and remained rare during the first days after birth. They increased in number, slowly until after weaning (15-20 days of age) and then more rapidly, until 25-30 days of age when the gastrin cell density reached that in adult rats. At the time of birth the gastrin concentration in serum was low; the subsequent increase during the first 2 weeks paralleled the development of the antral gastrin cell system. Adult postprandial serum gastrin concentrations were reached 12 days after birth. Somatostatin cells were rare in both the antral and oxyntic mucosa at birth. They increased gradually in number until about a month after birth when the cell density reached that seen in adult rats. In the oxyntic mucosa the ECL and A-like cells are the predominant endocrine (argyrophil) cell types. They were not detected until about 4 days after birth. Their number increased slowly until about 30 days of age. They did not stain argyrophil until about 2-4 weeks after birth. Parietal cells were few at birth; ultrastructurally they appeared to be in an active state and histochemically they were shown to contain carbonic anhydrase. The pH of the gastric content of newborn rats was close to 5; 15-17 days after birth the pH was about 4 in freely fed rats. In fasted rats shortly after birth the pH was about 4. Two weeks later it was around 2, which is the pH measured in older rats. Hence, the full capacity for acid secretion is probably not established until weaning. Fasting greatly lowers the serum gastrin concentration and the histidine decarboxylase activity of the ECL cells in adult rats. Before weaning, fasting produced these effects only to a minor degree.(ABSTRACT TRUNCATED AT 400 WORDS)

Mechanism of gastric acid response to pylorus ligation: effects of nephrectomy

In the rat nephrectomy raises the serum gastrin concentration but makes the parietal cells refractory to gastrin. Pylorus ligation stimulates the gastric acid output by a long vago-vagal reflex in innervated animals and by an intramural reflex in chronically vagotomized animals. Nephrectomy reduced the acid response to pylorus ligation in vagally intact rats but enhanced it in vagotomized rats. The acid response to pylorus ligation in all the experimental groups was inhibited by a muscarinic blocker, atropine, and by an H2-antagonist, metiamide. The serum gastrin concentration was raised by nephrectomy and by vagal denervation. Histamine mobilization from gastric endocrine cells is reflected in the activity of gastric histidine decarboxylase. The enzyme activity in pylorus-ligated innervated rats was raised by pentagastrin, atropine, and metiamide. In nephrectomized rats the basal enzyme activity was high, and it was raised further, slightly but significantly, by pentagastrin. The basal enzyme activity in pylorus-ligated rats was also quite high after vagotomy, and it was raised further by pentagastrin. After vagotomy + nephrectomy the basal enzyme activity was very high; it was not raised further by pentagastrin. It appears that both vago-vagal and intramural reflexes involve a cholinergic and a histaminergic pathway, that gastrin is not important for the neurally mediated acid response elicited by pylorus ligation, and that the postulated histaminergic pathway does not involve histamine derived from the gastric endocrine-like cells.

Effect of vagotomy on gastric acid secretion in the rat

The effects of pentagastrin, histamine or feeding on gastric acid secretion were studied in conscious rats with total gastric by-pass, achieved by transection of the cardia and pylorus, followed by an oesophago-duodenostomy. After closure of the cardia, the by-passed stomach was connected to the small intestine through a Roux-en-Y loop. A chronic gastric fistula was fitted into the rumen. Basal acid output was low in chronically vagotomized rats, being 6% of that in the innervated animals. A clear-cut stimulation was observed after both pentagastrin and histamine in innervated as well as denervated rats, although the maximal acid output in the denervated group was less than 10% of that in the innervated group. In previous studies on acid secretion in vagotomized rats with chronic gastric fistulas, neither basal nor stimulated acid secretion could be detected. Apparently, by-passing the stomach eliminates sources of error associated with the conventional gastric fistula technique (for instance, neutralization of acid gastric juice by swallowed saliva or regurgitated duodenal juice). Nonetheless, the greatly reduced acid output following vagotomy indicates that normal basal as well as normal stimulated acid secretion is dependent upon an intact vagus. Pentagastrin- and histamine-stimulated acid secretion was blocked by atropine and cimetidine in both the innervated and denervated rats. Feeding caused a significant inhibition of acid secretion in the by-passed, innervated stomach. In the denervated stomach feeding was without effect. The mechanism behind the postprandial inhibition of acid secretion in the innervated stomach is obscure. Direct vagal inhibition as well as humoral substances, liberated by vagal stimulation or by the presence of food in the intestine, may be responsible.

Gastric acid response to pylorus ligation in rats: is gastrin or histamine involved?

1. Pylorus ligation stimulated the acid output in vagally intact rats. The serum gastrin concentration and the gastric mucosal histamine content were not affected. The gastric histidine decarboxylase activity was initially slightly elevated and then greatly reduced (12-20 hr after ligation).2. Pylorus ligation stimulated the acid output in chronically, but not in acutely, vagotomized rats. Chronic vagotomy raises the serum gastrin concentration, the gastric histamine content and histidine decarboxylase activity. The serum gastrin concentration was further raised by pylorus ligation. The histamine content was initially lowered but returned to preligation values after 20 hr. The histidine decarboxylase activity first decreased, but increased to very high levels 5-6 hr after ligation. Twelve hours after ligation it was lower than before ligation.3. Following pylorus ligation pentagastrin and histamine stimulated the acid output in vagally intact and in acutely vagotomized but not in chronically vagotomized rats. By contrast, pentagastrin raised the histidine decarboxylase activity in vagally intact and in chronically vagotomized, but not in acutely vagotomized rats.4. The two major populations of endocrine cells of the oxyntic gland area (ECL cells and A-like cells) are argyrophil, store histamine and are capable of taking up exogenous DOPA and of decarboxylating it to dopamine which is retained in the cytoplasm for several hours. As evidenced by light and fluorescence microscopy pylorus ligation did not affect their argyrophilia or their ability to produce and store dopamine.5. Pylorus ligation caused ultrastructural changes in the gastrin cells of the pyloric gland area and in the histamine-storing ECL and A-like cells of the oxyntic gland area. The two endocrine cell types in the oxyntic gland area were enlarged by pylorus ligation, more so after 16 hr than after 4 hr. The size of the gastrin cells seemed unaffected. In all three cell types pylorus ligation reduced the number of cytoplasmic granules. There was no increase in the Golgi area or in the endoplasmic reticulum in any of the endocrine cell types of the oxyntic gland area. It appears unlikely that the ultrastructural changes of the ECL and A-like cells reflect an increased rate of histamine mobilization.6. The acid response to pylorus ligation probably reflects neuronal reflex mechanisms exclusively. There is no evidence that gastrin or histamine released from gastric endocrine cells mediate the response.

Luminal gastrin does not activate rat stomach histidine decarboxylase

Fasted rats have a low gastric histidine decarboxylase activity. I.v. infusion of heptadecapeptide gastrin for 2 h raised the enzyme activity. Intragastric perfusion with the same dose of gastrin and for the same period of time did not reproduce the effect of circulating gastrin. It is concluded that luminal gastrin, in contrast to circulating gastrin, does not activate rat stomach histidine decarboxylase.

Mechanisms of gastric acid secretion after pylorus and oesophagus ligation in the rat

1. The effect of vagotomy on gastric acid secretion was studied in chronic gastric fistula rats at various times after denervation. In these rats basal and pentagastrin-induced acid output was permanently reduced. Thus, the magnitude of the acid response to pentagastrin in the conscious fistula rat is dependent upon an intact vagus. 2. The acid response to pylorus ligation in vagally intact rats was unaffected by drainage of the stomach and therefore not caused by distension. Bilateral vagotomy, performed simultaneously with the ligation, completely abolished acid secretion, while unilateral vagotomy reduced the acid output by half. Hence, in innervated rats, an intact vagal impulse flow appears to be essential for the acid response to pylorus ligation. When the pylorus ligation was performed 2-8 weeks after truncal vagotomy, the acid output showed a progressive return towards pre-denervation values. In the denervated rats the acid response to pylorus ligation was blocked by drainage of the stomach and therefore probably caused by distension, a mechanism which is independent of the vagal impulse flow. 3. The response to pylorus ligation in innervated rats was blocked by atropine and chlorisondamine but not by metiamide. In the denervated rats, the response to pylorus ligation was blocked by all three drugs. 4. Following ligation of both the pylorus and the oesophagus the acid response was poor. With drainage of the oesophagus the acid response was much enhanced, suggesting that oesophageal distension inhibits acid secretion. In the vagotomized rat the poor acid response to oesophageal + pyloric ligation could not be overcome by drainage of the oesophagus. In the innervated rat gastric distension could overcome the inhibition induced by oesophageal ligation. Also in chronically, but not in acutely vagotomized rats, gastric distension brought about a good acid response. Conceivably, gastric reflex mechanisms can activate acid secretion through vagal and/or intramural pathways. Both in innervated and denervated rats the response to gastric distension was inhibited by atropine, chlorisondamine and metiamide. 5. The results suggest that in the innervated rat vago-vagal reflexes are important for the gastric hypersecretion following ligation of the pylorus, and for the acid response to gastric distension following ligation of the pylorus and oesophagus. In the chronically vagotomized rat local intramural reflexes elicited by gastric distension are responsible for the acid response.

Gastrin cell proliferation after chronic stimulation: effect of vagal denervation or gastric surgery in the rat

Chronic stimulation of the antral gastrin cells by elevated antral pH was achieved by fundectomy, antrum exclusion, fundectomy plus antrum exclusion, antrocolic transposition, and vagal denervation plus pyloroplasty. For comparison we studied also the effects of pyloroplasty alone and of portacaval shunting. All operations that elevated the antral pH resulted in high gastrin concentrations in serum. Particularly high concentrations were observed in fundectomized rats. Vagal denervation of fundectomized or antrum excluded rats reduced the serum gastrin concentration slightly compared with the corresponding innervated animals. Portacaval shunting reduced the gastrin concentration in serum. The antral gastrin concentration was raised or unchanged following fundectomy and vagal denervation, and reduced following antrum exclusion, antrum exclusion plus vagotomy, fundectomy plus antrum exclusion, fundectomy plus vagotomy, antrocolic transposition and portacaval shunt. The gastrin cell density in the antral mucosa was raised following fundectomy, vagotomy, and fundectomy plus vagotomy, unchanged following fundectomy plus antrum exclusion and antrocolic transposition, and reduced following antrum exclusion and portacaval shunting. Ultrastructurally the gastrin (G) cells in the excluded antrum and in the antrum of fundectomized rats showed signs of secretory activity in that the granule volume density or the number of granules per unit cytoplasm was lowered. In the fundectomized rats moreover, the endoplasmic reticulum of the G cells was increased, the Golgi area enlarged and the proportion and volume density of electron dense granules greatly increased. The granule profile diameter was not affected by either antrum exclusion or fundectomy. The results on the excluded antrum indicate that elevated antral pH per se is not sufficient to produce gastrin cell proliferation. In the fundectomized rats, where the hyperlasia of antral gastrin cells was considerable, there is the added stimulus of ingested food. In fundectomized plus antrum excluded rats this stimulus is eliminated and no proliferation ensues. The passage of intestinal material, as in the rats subjected to antrocolic transposition, did not elicit gastrin cell proliferation which seems to suggest that the character of the luminal material is important. We propose therefore that gastrin cell proliferation is due to the combined stimulation of high antral pH and passage of food. Vagal innervation is not required.

Gastrin: obligatory intermediate in the postprandial mobilization of gastric histamine in the rat

In unoperated fasted rats, feeding raised the serum gastrin concentration, reduced the gastric mucosal histamine content and activated the gastric histidine decarboxylase. The reduction of gastric histamine and activation of histidine decarboxylase was induced also by the injection of pentagastrin. In antrectomized rats, feeding failed to produce these effects. Injection of pentagastrin, however, still lowered gastric histamine and activated gastric histidine decarboxylase. Thus, antral gastrin seems to be an obligatory mediator of the postprandial activation of histidine decarboxylase and mobilization of histamine.

Activation of histidine decarboxylase by H2-receptor blockade: mechanism of action

1 Treatment with histamine H2-receptor antagonists, which inhibit basal acid secretion was found to activate rat stomach histidine decarboxylase. At the same time the serum gastrin concentration was greatly increased. 2 In antrectomized rats neither the enzyme activity nor the serum gastrin concentration was affected by the treatment. 3 In analogy with previous observations on other inhibitors of acid secretion we suggest that the H2-receptor antagonists stimulate gastrin release through their effect on acid secretion and that the raised serum gastrin level is responsible for the enzyme activation.