Visceral hypersensitivity and impaired accommodation in refractory diabetic gastroparesis

Decreased gastric motility in type II diabetic patients

Background. To differentiate gastric motility and sensation between type II diabetic patients and controls and explore different expressions of gastric motility peptides. Methods. Eleven type II diabetic patients and health volunteers of similar age and body mass index were invited. All underwent transabdominal ultrasound for gastric motility and visual analogue scales. Blood samples were taken for glucose and plasma peptides (ghrelin, motilin, and glucacon-like peptides-1) by ELISA method. Results. Gastric emptying was significantly slower in diabetic patients than controls (T50: 46.3 (28.0–52.3) min versus 20.8 (9.6–22.8) min, P ≤ 0.05) and less antral contractions in type II diabetic patients were observed (P = 0.02). Fundus dimensions did not differ. There were a trend for less changes in gastrointestinal sensations in type II diabetic patients especially abdomen fullness, hunger, and abdominal discomfort. Although the serum peptides between the two groups were similar a trend for less serum GLP-1in type II diabetic patients was observed (P = 0.098). Conclusion. Type II diabetic patients have delayed gastric emptying and less antral contractions than controls. The observation that there were lower serum GLP-1 in type II diabetic patients could offer a clue to suggest that delayed gastric emptying in diabetic patients is not mainly influenced by GLP-1.

Emerging drugs for the treatment of gastroparesis

INTRODUCTION

Gastroparesis presents with symptoms of gastric retention with findings of delayed gastric emptying on diagnostic testing. Manifestations of gastroparesis are disabling in severe cases and lead to significant health resource utilization. Current therapies often are ineffective, may exhibit tolerance on chronic administration or produce prominent side effects in large patient subsets.

AREAS COVERED

This review assessed literature on drugs with theoretical efficacy in gastroparesis including medications that accelerate gastric emptying, reduce nausea and vomiting, or act as neuromodulators to reduce gastric sensitivity. Numerous agents exhibit diverse actions to modify gastric sensorimotor function in animal models; however, few medications are in controlled testing in gastroparesis. Prokinetic drugs with promise for this condition include investigational serotonin 5-HT4 agonists, motilin agonists, dopamine D2 antagonists, ghrelin agonists and an agent with combined muscarinic antagonist and acetylcholinesterase inhibitory effects. Other antiemetics and complementary and alternative formulations may be effective for some symptoms.

EXPERT OPINION

Development of effective novel therapies of gastroparesis without the neurotoxicity and cardiac arrhythmogenic effects of current agents will mandate a better definition of the gastric and extragastric factors responsible for the pathogenesis of the varied clinical manifestations of this disorder.

Gastroparesis: what is the current state-of-the-art for evaluation and medical management? What are the results?

Gastroparesis is a chronic motility disorder that leads to delayed gastric emptying and negatively impacts morbidity, mortality, and quality of life. This paper provides an overview of the pathophysiology leading to symptoms in gastroparesis, discusses tests for diagnosis, and examines the evidence behind different treatment options for gastroparesis. Although delayed gastric emptying is the cardinal finding in gastroparesis, other physiologic abnormalities may contribute to the pathogenesis of symptoms. Gastric emptying scintigraphy is considered the gold standard for the diagnosis of gastroparesis but novel tests are currently available. Although metoclopramide is the only FDA approved medication to treat gastroparesis, alternative therapeutic options are available and should be tailored according to symptoms as well as physiologic abnormalities.

Factors related to abdominal pain in gastroparesis: contrast to patients with predominant nausea and vomiting

BACKGROUND

Factors associated with abdominal pain in gastroparesis are incompletely evaluated and comparisons of pain vs other symptoms are limited. This study related pain to clinical factors in gastroparesis and contrasted pain/discomfort- with nausea/vomiting-predominant disease.

METHODS

Clinical and scintigraphy data were compared in 393 patients from seven centers of the NIDDK Gastroparesis Clinical Research Consortium with moderate-severe (Patient Assessment of Upper Gastrointestinal Disorders Symptoms [PAGI-SYM] score ≥ 3) vs none-mild (PAGI-SYM < 3) upper abdominal pain and predominant pain/discomfort vs nausea/vomiting.

KEY RESULTS

Upper abdominal pain was moderate-severe in 261 (66%). Pain/discomfort was predominant in 81 (21%); nausea/vomiting was predominant in 172 (44%). Moderate-severe pain was more prevalent with idiopathic gastroparesis and with lack of infectious prodrome (P ≤ 0.05) and correlated with scores for nausea/vomiting, bloating, lower abdominal pain/discomfort, bowel disturbances, and opiate and antiemetic use (P < 0.05), but not gastric emptying or diabetic neuropathy or control. Gastroparesis severity, quality of life, and depression and anxiety were worse with moderate-severe pain (P ≤ 0.008). Factors associated with moderate-severe pain were similar in diabetic and idiopathic gastroparesis. Compared to predominant nausea/vomiting, predominant pain/discomfort was associated with impaired quality of life, greater opiate, and less antiemetic use (P < 0.01), but similar severity and gastric retention.

CONCLUSIONS & INFERENCES

Moderate-severe abdominal pain is prevalent in gastroparesis, impairs quality of life, and is associated with idiopathic etiology, lack of infectious prodrome, and opiate use. Pain is predominant in one fifth of gastroparetics. Predominant pain has at least as great an impact on disease severity and quality of life as predominant nausea/vomiting.

Mechano-transcription of COX-2 is a common response to lumen dilation of the rat gastrointestinal tract

BACKGROUND

In obstructive bowel disorders (OBDs) such as achalasia, pyloric stenosis, and bowel obstruction, the lumen of the affected segments is markedly dilated and the motility function is significantly impaired. We tested the hypothesis that mechanical stress in lumen dilation leads to induction of cyclooxygenase-2 (COX-2) in smooth muscle throughout the gastrointestinal (GI) tract, contributing to motility dysfunction.

METHODS

Lumen dilation was induced in vivo with obstruction bands (12 × 3 mm) applied over the lower esophageal sphincter (LES), the pyloric sphincter, and the ileum in rats for 48 h. Mechanical stretch in vivo was also emulated by balloon distension of the distal colon. Direct stretch of muscle strips from the esophagus, gastric fundus, and ileum was mimicked in an in vitro tissue culture system.

KEY RESULTS

Partial obstruction in the LES, pylorus, and ileum significantly increased the expression of COX-2 mRNA and protein in the muscularis externae of the dilated segment oral to the occlusions, but not in the aboral segment. Direct stretch of the lumen in vivo or of muscle strips in vitro markedly induced COX-2 expression. The smooth muscle contractility was significantly suppressed in the balloon-distended segments. However, treatment with COX-2 inhibitor NS-398 restored the contractility. Furthermore, in vivo administration of NS-398 in gastric outlet obstruction significantly improved gastric emptying.

CONCLUSIONS & INFERENCES

Mechanical dilation of the gut lumen by occlusion or direct distension induces gene expression of COX-2 throughout the GI tract. Mechanical stress-induced COX-2 contributes to motility dysfunction in conditions with lumen dilation.

Gastrointestinal symptoms in diabetes mellitus, and their relation to anxiety and depression

BACKGROUND

Prevalence of gastrointestinal (GI) symptoms is increased in patients with diabetes mellitus. In general, GI symptoms are influenced by psychological factors such as anxiety and depression, but little is known about this association in diabetic patients.

AIM

We tested the hypothesis that anxiety and depression have major impact on GI symptoms in diabetic patients.

METHODS

280 diabetic patients and 355 non-diabetic, age and sex matched controls were studied by validated questionnaires: (1) PAGI-SYM and GSRS for common GI symptoms and (2) HADS for anxiety and depression. Data were compared using logistic regression analysis.

RESULTS

Patients with diabetes scored significantly (p<0.05) higher on the symptoms diarrhea (OR 1.64, 95% CI 1.05-2.56), early satiety (OR 2.50, 95% CI 1.39-4.49) and bloating (OR 1.58, 95% CI 1.03-2.43), but not on other symptoms. Prevalence of anxiety and depression (HADS scores ≥ 8) in diabetics and controls was respectively 27.5% and 20.6% for anxiety (p<0.05), and 19.6% and 13.4% for depression (p<0.05). After adjusting for anxiety and depression only the GI symptom "early satiety" remained significantly more prevalent in the patients with diabetes.

CONCLUSIONS

The prevalence of the gastrointestinal symptoms diarrhea, bloating and early satiety, and of anxiety and depression is significantly increased in our cohort of predominantly patients with longstanding type 2 diabetes mellitus compared to controls. When adjusted for anxiety and depression, only the gastrointestinal symptom "early satiety" remained more prevalent in these diabetic patients, pointing to a somatic based origin. Thus, in our diabetic population psychological factors to a large extent are associated with gastrointestinal symptoms and should be taken into account when considering treatment of the gastrointestinal symptoms.

Evaluating symptom outcomes in gastroparesis clinical trials: validity and responsiveness of the Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD)

BACKGROUND

Patient-reported symptom scales are needed to evaluate treatments for gastroparesis. The Gastroparesis Cardinal Symptom Index-Daily Diary (GCSI-DD) was developed to assess daily symptoms of gastroparesis. This study evaluated the validity and responsiveness of the GCSI-DD in patients with gastroparesis.

METHODS

Symptomatic patients were started with a new treatment for gastroparesis. Patients completed the GCSI-DD each evening during a baseline week and for 8 weeks of treatment. Responders were defined based on patient and clinician global rating of change. Minimal important differences (MID) were estimated based on baseline to 4 week changes in symptoms scores for small improvements.

KEY RESULTS

Of 69 patients participating, 46 had idiopathic, 19 diabetic, and four postfundoplication gastroparesis. Excellent test-retest reliability was seen for GCSI-DD scores, and there were significant correlations between GCSI-DD scores and clinician ratings of symptom severity. Responders to treatment reported improvements in nausea [effect size (ES) = 0.42, P < 0.001], postprandial fullness, ES = 0.83, P < 0.001), bloating (ES = 0.34, P < 0.001), early satiety (ES = 0.53, P < 0.001), but lower responses for upper abdominal pain (ES = 0.29), and vomiting (ES = 0.22; P = 0.119). MIDs were 0.55 for nausea, 0.97 for excessive fullness, 0.63 for bloating, 0.77 for postprandial fullness, and 0.30 for abdominal pain. A composite score of four symptoms (Composite-1; nausea, bloating, excessive fullness, postprandial fullness) had ES of 0.61 and MID of 0.73. Composite-2 score (nausea, early satiety, bloating, abdominal pain) had a lower ES of 0.47.

CONCLUSIONS & INFERENCES

Symptoms of early satiety, nausea, postprandial fullness, and bloating were responsive to treatment for gastroparesis. A composite of these symptoms also demonstrates validity and responsiveness to treatment for gastroparesis, and may represent an acceptable endpoint for evaluating the effectiveness of medical treatments in clinical trials for gastroparesis.

Role of transient receptor potential ankyrin 1 in gastric accommodation in conscious guinea pigs

We report the establishment of a new model for measuring gastric tone and liquid meal-induced accommodation in conscious guinea pigs and the role played by transient receptor potential ankyrin 1 (TRPA1). An indwelling polyethylene bag was placed in proximal stomachs of 5-week-old male Hartley guinea pigs. Gastric tone was measured by distending the bag and recording changes in intrabag pressure at various volumes. Gastric accommodation was measured by administering liquid meals and recording intrabag pressure over time. N(ω)-nitro-L-arginine methyl ester hydrochloride (L-NAME) (a nitric-oxide synthase inhibitor), atropine sulfate (atropine) (a muscarinic receptor antagonist), allyl isothiocyanate (AITC) (a TRPA1 agonist), or theophylline-7-(N-4-isopropylphenyl) acetamide (HC-030031) (a selective TRPA1 antagonist) was administered 15 to 60 min before measurement. Gastric tone was increased by stepwise distension of the bag and was further significantly increased by L-NAME and significantly decreased by atropine. A liquid meal (15% w/v; 1.7 kcal) significantly decreased intrabag pressure 5 to 20 min after administration, indicating gastric accommodation; this was completely suppressed by L-NAME and further enhanced by atropine. AITC significantly increased gastric tone; this increase was decreased by HC-030031 and atropine. A combination of AITC and L-NAME significantly increased gastric tone compared with L-NAME alone. HC-030031 alone significantly decreased gastric tone. Liquid meal-induced gastric accommodation was significantly suppressed by pretreatment with AITC. We established a new model for measuring gastric tone and accommodation in conscious guinea pigs. TRPA1 activation suppresses gastric accommodation by increasing gastric tone through cholinergic neuronal pathways.

Prevalence of gastroparesis-related symptoms in an unselected cohort of patients with Type 1 diabetes

BACKGROUND

The prevalence of diabetic gastroparesis is not well defined because of discrepancy between objective measurements, i.e. gastric emptying time, and symptoms experienced by patients. Furthermore most studies have been performed on small selected cohorts.

OBJECTIVE

To determine the prevalence of clinical symptoms of diabetic gastroparesis in a large unselected cohort of out-patients with Type 1 diabetes.

METHODS

1028 patients with Type 1 diabetes attending a specialized diabetes clinic were mailed a validated questionnaire; "patient assessment of upper gastrointestinal disorders-symptom severity index", in which a subset of questions measures symptoms of gastroparesis (GCSI; Gastroparesis Cardinal Symptom Index). Response rate was 74.4% (n=765). All patients were classified according to presence or absence of late diabetic complications and clinical and paraclinical data were obtained.

RESULTS

A GCSI Total Score ≥1.90 signified definite symptoms of gastroparesis (n=102) and patient charts were investigated for concomitant illness and/or medication influencing gastric emptying. In 30 patients an alternative etiology was revealed, leaving 72 (9.8%) patients with symptoms related to diabetic gastroparesis. Only 8 patients were previously diagnosed. HbA(1c) levels were significantly higher in patients with diabetic gastroparesis (8.4±1.3 vs. 8.2±1.2 respectively, p=0.02). Furthermore, patients with diabetic gastroparesis had more retinopathy (p=0.006) and peripheral polyneuropathy (16.7% vs. 6.7%, p<0.001) and there was a trend for diabetic nephropathy being more common (p=0.08).

CONCLUSIONS

Symptoms of diabetic gastroparesis affect approximately 10% of patients with Type 1 diabetes in a specialized diabetes clinic and are associated with poor glycemic control and other late diabetic complications.

Gastroparesis: concepts, controversies, and challenges

Patients with gastroparesis often present a challenge to the treating physician. Postprandial symptoms with nausea and vomiting may not only lead to nutritional and metabolic consequences, but also cause significant disruptions to social activities that often center around food. While the definition of gastroparesis focuses on impaired gastric emptying, treatment options that affect gastric function are limited and often disappointing. The female predominance, the mostly idiopathic nature of the illness with a common history of abuse, and coexisting anxiety or depression show parallels with other functional disorders of the gastrointestinal tract. These parallels provided the rationale for some initial studies investigating alternative therapies that target the brain rather than the stomach. This emerging shift in medical therapy comes at a time when clinical studies suggest that gastric electrical stimulation may exert its effects by modulating visceral sensory processing rather than altering gastric motility. Physiologic and detailed anatomic investigations also support a more complex picture with different disease mechanisms, ranging from impaired accommodation to apparent visceral hypersensitivity or decreased interstitial cells of Cajal to inflammatory infiltration of myenteric ganglia. Delayed gastric emptying remains the endophenotype defining gastroparesis. However, our treatment options go beyond prokinetics and may allow us to improve the quality of life of affected individuals.

Neostigmine-induced contraction and nitric oxide-induced relaxation of isolated ileum from STZ diabetic guinea pigs

Both delayed gastrointestinal transit and autonomic neuropathy have been documented in patients with diabetes mellitus. The mechanism of neostigmine, an agent that mimics release of acetylcholine from autonomic neurons by prokinetic agents, to contract smooth muscle, despite dysfunctional enteric neural pathways, was determined using isolated ilea from STZ-treated and control guinea pigs. Both bethanechol- and neostigmine-induced contractions were stronger in diabetic ileum. Bethanechol-induced contractions of control but not diabetic ileum were increased by low dose scopolamine suggesting reduced activation of presynaptic muscarinic autoreceptors in diabetic ileum. The muscarinic receptor antagonist 4-DAMP strongly, but the nicotinic receptor antagonist hexamethonium only weakly, reduced neostigmine-induced contractions of control and diabetic ilea. The amount of acetylcholine, inferred from tissue choline content, was increased in diabetic ileum. Nicotinic neural and noncholinergic postjunctional smooth muscle receptors contributed more strongly to neostigmine-induced contractions in diabetic than control ileum. Relaxation of diabetic ileum by exogenous nitric oxide generated from sodium nitroprusside was comparable to control ileum, but smooth muscle relaxation by l-arginine using neuronal nitric oxide synthase to generate nitric oxide was weaker in diabetic ileum with evidence for a role for inducible nitric oxide synthase. Despite autonomic neuropathy, neostigmine strongly contracted ileum from diabetic animals but by a different mechanism including stronger activation of postjunctional muscarinic receptors, greater synaptic acetylcholine, stronger activation of noncholinergic excitatory pathways, and weaker activation of inhibitory pathways. A selective medication targeting a specific neural pathway may more effectively treat disordered gastrointestinal transit in patients with diabetes mellitus.

Gastroparesis: pathogenesis, diagnosis and management

Gastroparesis is a prevalent condition that produces symptoms of delayed gastric emptying in the absence of physical blockage. The most common etiologies of gastroparesis are idiopathic, diabetic, and postsurgical disease, although some cases stem from autoimmune, paraneoplastic, neurologic or other conditions. Histologic examination of gastric tissues from patients with severe gastroparesis reveals heterogeneous and inconsistent defects in the morphology of enteric neurons, smooth muscle and interstitial cells of Cajal, and increased levels of inflammatory cells. Diagnosis is most commonly made by gastric emptying scintigraphy; however, wireless motility capsules and nonradioactive isotope breath tests have also been validated. A range of treatments have been used for gastroparesis including dietary modifications and nutritional supplements, gastric motor stimulatory or antiemetic medications, endoscopic or surgical procedures, and psychological interventions. Most treatments have not been subjected to controlled testing in patients with gastroparesis. The natural history of this condition is poorly understood. Active ongoing research is providing important insights into the pathogenesis, diagnosis, treatment and outcomes of this disease.

Diabetic gastroparesis-backwards and forwards

Diabetic gastroparesis was once thought to be rare, associated with a poor prognosis, and to affect only patients with type 1 diabetes and irreversible autonomic neuropathy. A landmark study conducted by Horowitz et al. and published in JGH in 1986 paved the way for further studies to examine the pathophysiology, natural history and prognosis of diabetic gastroparesis, as well as its optimal management. This review summarizes the developments in knowledge gained over the last ∼25 years that have led to understanding about normal and disordered gastric emptying in diabetes, with a particular emphasis on the inter-relationship between the rate of gastric emptying and the regulation of blood glucose.

Regional differences in neostigmine-induced contraction and relaxation of stomach from diabetic guinea pig

Delayed gastric emptying and autonomic neuropathy have been documented in patients with diabetes mellitus. Some medications used to treat delayed gastric emptying enhance release of acetylcholine from autonomic neurons to strengthen gastric contractions. Autonomic coordination among gastric regions may be altered in diabetes resulting in poor outcomes in response to prokinetic drugs. Fundus, antrum, and pylorus from STZ or control guinea pigs were treated with neostigmine to mimic release of acetylcholine from autonomic neurons by prokinetic agents. In diabetic animals, neostigmine-induced contractions were weaker in fundus and pylorus but similar in antrum. The muscarinic receptor antagonist 4-DAMP or the nicotinic receptor antagonist hexamethonium reduced neostigmine-induced contractions. Activation of presynaptic muscarinic receptors on nitrergic neurons was impaired in fundus and antrum from diabetic animals. Nerve-stimulated contractions and relaxations, number of nNOS myenteric neurons, and tissue choline content were reduced in fundus from diabetic animals. Despite reduced number of myenteric neurons, tissue choline content was increased in antrum from diabetic animals. Since cholinergic motility of each gastric region was affected differently by diabetes, prokinetic drugs that nondiscriminately enhance acetylcholine release from autonomic neurons may not effectively normalize delayed gastric emptying in patients with diabetes and more selective medications may be warranted.

Comparison of metabolic and neuropathy profiles of rats with streptozotocin-induced overt and moderate insulinopenia

To assess the relative roles of insulinopenia, hyperglycemia and dyslipidemia in pathogenesis of diabetic neuropathy, we compared plasma insulin, glucose and lipid metabolism and peripheral nerve function in rats with streptozotocin (STZ)-induced overt and moderate insulinopenia (hyperglycemic, STZ-HG; random glucose>11 mM and normoglycemic, STZ-NG rats). While being slightly insulinopenic, STZ-NG rats are metabolically not different from control, naive animals, by having normal glucose tolerance and normal levels of plasma glucose, glycated HbA1c, cholesterol and triglycerides. Two weeks following injection of STZ, STZ-HG but not STZ-NG rats had suppressed motor nerve conduction velocity, F-wave prevalence, withdrawal responses to heat and von Frey filament stimuli. In apparent correlation with plasma insulin level, both STZ-HG and -NG rats manifested exaggerated responses in paw pressure and colorectal distension tests. These data suggest that insulinopenia may play a leading role in the diabetic impairment of deep muscle and visceral afferent pathways while hyperglycemia/dyslipidemia may represent a key requirement for the onset and progression of electrophysiological nerve impairment and loss of superficial heat and tactile perception. STZ-NG rats offer a convenient model for the investigation of the short-term effects of insulinopenia on peripheral nerve function.

Gastric motor and sensory function

PURPOSE OF REVIEW

Abnormalities of gastric sensory and motor function are considered key players in the pathogenesis of upper gastrointestinal symptoms in functional dyspepsia and in gastroparesis. This review summarizes recent progress in our understanding of gastric sensory and motor function in health and in disease.

RECENT FINDINGS

Although assessment of gastric emptying rate is often used in the clinical work-up of patients with functional dyspepsia or gastroparesis, the correlation with symptoms is generally poor. Central processing, related to psychosocial dysfunction, is increasingly implicated in the pathogensis of gastric hypersensitivity. Meal challenge test and in fact even simple ingestion of a meal induce increased symptom occurrence in functional dyspepsia. Impaired motor function in critically ill patients is increasingly being studied and recognized as a prognostically relevant factor. Studies have reported on pharmacological approaches as well as electrical stimulation in the treatment of gastric sensorimotor dysfunction.

SUMMARY

Progress in our understanding of the normal and abnormal gastric sensory and motor function may lead to new or improved treatment modalities. Areas of recent advances are the role of the central nervous system in visceral hypersensitivity, motor abnormalities of the stomach in critically ill patients and the exploration of novel pharmacotherapeutic approaches.

Diabetic gastroparesis: diagnosis and management

Gastric emptying is frequently abnormal in patients with long-standing type 1 and type 2 diabetes mellitus. Symptoms commonly associated with disordered gastric emptying include nausea, vomiting, bloating and epigastric pain, while patients are also at risk of malnutrition, weight loss, impaired drug absorption, disordered glycaemic control and poor quality of life. Although often attributed to the presence of irreversible autonomic neuropathy, acute hyperglycaemia represents a potentially reversible cause of gastric dysfunction in diabetes. Scintigraphy represents the gold standard for measuring gastric emptying. The management of diabetic gastroparesis is less than optimal, partly because the pathogenesis has not been clearly defined. Treatment approaches include dietary modification and optimization of glycaemia, and the use of prokinetic drugs, while novel therapies such as gastric electrical stimulation are the subject of ongoing investigation.

Tests of gastric neuromuscular function

Tests of gastric neuromuscular function are used to evaluate patients with symptoms referable to the upper digestive tract. These symptoms can be associated with alterations in the rates of gastric emptying, impaired accommodation, heightened gastric sensation, or alterations in gastric myoelectrical function and contractility. Management of gastric neuromuscular disorders requires an understanding of pathophysiology and treatment options as well as the appropriate use and interpretation of diagnostic tests. These tests include measures of gastric emptying; contractility; electrical activity; regional gastric motility of the fundus, antrum, and pylorus; and tests of sensation and compliance. Tests are also being developed to improve our understanding of the afferent sensory pathways from the stomach to the central nervous system that mediate gastric sensation in health and gastric disorders. This article reviews tests of gastric function and provides a basic description of the tests, the methodologies behind them, descriptions of the physiology that they assess, and their clinical utility.

Pathophysiology and management of gastroparesis

Gastroparesis is characterized by upper gastrointestinal symptoms associated with delayed gastric emptying, without mechanical obstruction. However, symptoms do not correlate well with the magnitude of delay in gastric emptying. Diabetes mellitus and surgery are the most common causes, although more than 30% of cases are idiopathic. Coordination of insulin action with nutrient delivery is important in diabetics, as postprandial blood glucose levels and gastric emptying are interdependent, and gastroparesis probably represents a major cause of poor glycemic control. Scintigraphy is the gold standard for measuring gastric emptying. Current treatment mainly involves the use of prokinetic drugs. Pyloric botulinum toxin injection and gastric electrical stimulation require more evidence from controlled studies before their use can be recommended. Surgical options remain inadequately studied.

Synchronized gastric electrical stimulation improves vagotomy-induced impairment in gastric accommodation via the nitrergic pathway in dogs

Impaired gastric accommodation and gastric dysrhythmia are common in gastroparesis and functional dyspepsia. Recent studies have shown that synchronized gastric electrical stimulation (SGES) accelerates gastric emptying and enhances antral contractions in dogs. The aim of this study was to investigate the effects and mechanism of SGES on gastric accommodation and slow waves impaired by vagotomy in dogs. Gastric tone, compliance, and accommodation as well as slow waves with and without SGES were assessed in seven female regular dogs and seven dogs with bilateral truncal vagotomy, chronically implanted with gastric serosal electrodes and a gastric cannula. We found that 1) vagotomy impaired gastric accommodation that was normalized by SGES. The postprandial increase in gastric volume was 283.5 +/- 50.6 ml in the controlled dogs, 155.2 +/- 49.2 ml in the vagotomized dogs, and 304.0 +/- 57.8 ml in the vagotomized dogs with SGES. The ameliorating effect of SGES was no longer observed after application of N(omega)-nitro-L-arginine (L-NNA); 2) vagotomy did not alter gastric compliance whereas SGES improved gastric compliance in the vagotomized dogs, and the improvement was also blocked by L-NNA; and 3) vagotomy impaired antral slow wave rhythmicity in both fasting and fed states. SGES at the proximal stomach enhanced the postprandial rhythmicity and amplitude (dominant power) of the gastric slow waves in the antrum. In conclusion, SGES with appropriate parameters restores gastric accommodation and improves gastric slow waves impaired by vagotomy. The improvement in gastric accommodation with SGES is mediated via the nitrergic pathway. Combined with previously reported findings (enhanced antral contractions and accelerated gastric emptying) and findings in this study (improved gastric accommodation and slow waves), SGES may be a viable therapy for gastroparesis.