Relation of symptoms to impaired stomach, small bowel, and colon motility in long-standing diabetes

Gastrointestinal motor function in diabetes mellitus: Relationship to blood glucose concentrations

The application of novel investigative techniques has established that there is a high prevalence of disordered gastrointestinal motor function in patients with diabetes mellitus and has provided insights into its pathogenesis and clinical significance. Acute changes in the blood glucose concentration, even within the normal postprandial range, affect both gastrointestinal motor function and the perception of sensations arising from the gastrointestinal tract. Gastric emptying is slower during hyperglycaemia and accelerated during hypoglycaemia; the perception of gastric distension is greater during hyperglycaemia than euglycaemia. The pathways mediating the effects of the blood glucose concentration on gut motility and sensation are poorly defined. The rate of gastric emptying is an important determinant of postprandial blood glucose concentrations and there is increasing evidence that gastric emptying can be modulated therapeutically in order to optimize glycaemic control in patients with diabetes.

Comparison of relaxations evoked by photoactivation of NO-containing compounds and nitrergic nerve stimulation in 5-hydroxytryptamine- and potassium-contracted rat gastric fundus

1. The aim of the present study was to further investigate our earlier proposal of liberation of nitric oxide (NO) by photoactivation of molecules containing NO or NO2, which in turn relaxes gastric smooth muscle, and to determine whether presynaptic- and/or postsynaptic NO-mediated relaxation is affected differently by the degree of membrane depolarization in rat gastric fundus smooth muscle. 2. During contraction of rat gastric fundus with 5-hydroxytryptamine (5-HT, 10 microM), low (K+, 25 mM) and high potassium (K+, 65.4 mM), relaxation responses to nitrergic nerve stimulation, photo-activation of caged NO compounds (streptozotocin [STZ], N omega-nitro-L-arginine-methylacetate [L-NAME], N omega-nitro-D-arginine-methylacetate [D-NAME]), and sodium nitroprusside (SNP) were compared. 3. Nitrergic nerve (presynaptic) stimulation and photoactivation (postsynaptic) of all caged NO compounds produced rapid, transient and reversible relaxation of 5-HT and low-K(+)-contracted tissues. However, when contractions were induced by high K+, the relaxation induced by nerve stimulation was abolished, whereas relaxations induced by photoactivated NO compounds were significantly (P < 0.01) reduced. 4. The relaxation induced by sodium nitroprusside (SNP), but not papaverine, was also diminished in high-K(+)-contracted tissues. The magnitude of photoactivated NO-induced relaxation was related to the amount of NO release, light intensity and concentration of compounds. 5. The evidence that photoactivated NO-induced relaxation is mediated by cGMP comes from the observation that zaprinast, but not forskolin, potentiated the relaxation. 6. It is concluded that rat gastric smooth muscle relaxes to photoactivation of NO or NO2-carrying molecules via NO, and it appears that degree of membrane depolarization may be a critical factor in dissociating the response to presynaptic- and postsynaptic NO-mediated relaxation in this muscle.

Morphological and quantitative analysis of the neurons of the myenteric plexus of the cecum of streptozotocin-induced diabetic rats

The purpose of this work was to study the neurons of the myenteric plexus of the cecum of rats with chronic streptozotocin-induced diabetes. We used four experimental groups of animals. In groups D2 and D8 animals were killed two and eight months, respectively, after diabetes induction and groups C2 and C8 were used as controls. We carried out whole-mount preparations stained with Giemsa and NADH-diaphorase. We verified that the diabetes did not alter the shape and disposition of the myenteric ganglia; it provoked decrease on the neuronal density and increase on the incidence of weakly basophilic neurons. The effects of streptozotocin caused dilatation of the cecum still evidenced two months after induction, but no more observed on the eight months after induction. The smaller incidence of neurons in group D8 relative to group C8 was due to the early loss related to the drug toxicity and later to the aging in diabetic condition.

Cisapride and erythromycin prokinetic effects in gastroparesis due to type 1 (insulin-dependent) diabetes mellitus

BACKGROUND

Erythromycin, a macrolide antibiotic, has been shown to have gastric prokinetic effects and has been proposed as an alternative therapeutic option for diabetic gastroparesis. However, its efficacy has not yet been compared with that of other prokinetic drugs.

AIMS

The purpose of the present study was to compare the effects of erythromycin (250 mg 60 min before meals) and cisapride (10 mg 30 min before meals) on gastric emptying of healthy subjects and insulin-dependent diabetics.

PATIENTS AND METHODS

Six type 1 diabetic patients with a previous scintigraphic demonstration of gastroparesis and five healthy subjects were recruited for the study. Gastric emptying was scintigraphically studied by labelling the solid component of a standard test meal. Three scintigraphic studies, spaced at least 3 days apart, were carried out on each subject, basally and after erythromycin or cisapride.

RESULTS

Cisapride significantly accelerated gastric emptying in both the healthy subjects and the diabetic patients without any significant effect on the lag-time, whereas erythromycin in addition to a significant improvement of the overall gastric emptying also showed a pronounced effect on the lag-time in both groups (controls 25 +/- 5 vs. 37 +/- 8 min, P < or = 0.04; diabetics 65 +/- 11 vs. 112 +/- 16 min, P < 0.03).

CONCLUSIONS

Erythromycin may represent an effective therapeutic alternative to more established forms of treatment in patients with diabetic gastroparesis, especially when other drugs have failed.

Electrogastrography and gastric emptying scintigraphy are complementary for assessment of dyspepsia

We have tried to correlate abnormalities in electrogastrography (EGG) and gastric emptying (GE) with symptom severity in patients with functional dyspepsia. Seventy-two patients with functional dyspepsia underwent EGG, GE, and symptom severity quantitation. EGGs were assessed for dominant frequency (DF), percentage of time of DF in the 2 to 4 cpm range, and postprandial-fasting DF power ratio. Solid-phase GE scintigraphy was assessed for 2-hour percentage retention. Symptoms of upper abdominal discomfort, early satiety, postprandial abdominal distension, nausea, vomiting, and anorexia were graded as none (0), mild (1), moderate (2), and severe (3); the sum represented a total symptom score. The EGG was abnormal in 11 of 22 (50%) patients with delayed GE compared with 11 of 50 (22%) with normal GE (p < 0.025). The total symptom scores were higher in patients with both delayed GE and abnormal EGG compared with patients with normal GE and EGG, normal GE and abnormal EGG, and delayed GE and normal EGG. We conclude that EGG abnormalities are more common in dyspeptic patients with delayed GE. Patients with both delayed GE and abnormal EGG have more severe symptoms. Our results suggest that EGG and GE complement each other in correlating symptoms to gastric dysmotility.

Gastric and small intestinal motility in health and disease

Although symptoms possibly related to motor dysfunction appear to be common, primary disorders of the foregut motor apparatus, defined on the basis of a discrete myoneural pathology, are notably rare. This phenomenon may as much reflect the relatively primitive nature of diagnostic methods as the true rarity of such disorders. Although diagnostic methodologies increase in sophistication and availability, their clinical impact has been limited by an imperfect relationship between symptoms and dysfunction and by a relatively poor ability of such tests to predict response to available therapeutic strategies. An ever-increasing understanding of the complex, often interrelated motor and sensory phenomena that contribute to symptoms, together with the development of consensus on the use and interpretation of motility tests and the more widespread application of sophisticated histologic, immunologic, biochemical, and molecular biologic methodologies to the study of these disorders, should lead, in the years to come, to much needed progress in this area.

Mechanism of accelerated gastric emptying of liquids and hyperglycemia in patients with type II diabetes mellitus

BACKGROUND & AIMS

The roles of hyperglycemia in diabetic gastroparesis and gastric delivery in postprandial hyperglycemia of diabetic patients are unclear. The aims of this study were to assess gastric emptying and its relation to postprandial glucose metabolism in patients with asymptomatic non-insulin-dependent diabetes mellitus (NIDDM) and no autonomic neuropathy and to identify motor mechanisms responsible for any accelerated gastric emptying.

METHODS

Autonomic function, gastric emptying, postprandial glucose metabolism, and hormone levels (glucagon, insulin, cholecystokinin, glucose-dependent insulinotropic polypeptide, neurotensin, and peptide YY) were assessed in healthy volunteers and patients with NIDDM. In a second study, gastric tone and motility were measured in patients with accelerated gastric emptying and in controls.

RESULTS

Gastric emptying of solids did not differ in the two groups, but liquids emptied faster in patients with NIDDM (P < 0.02). The rate of entry of ingested glucose into the systemic circulation was similar, but higher postprandial glucagon and lower insulin concentrations led to greater (P < 0.01) postprandial hepatic glucose release. Levels of other enteropeptides, gastric accommodation, and antral motility were similar, but patients with NIDDM had greater proximal gastric phasic contractions than controls (P < 0.05).

CONCLUSIONS

Excessive hepatic glucose release, not rapid entry of ingested glucose, is the primary cause of postprandial hyperglycemia in patients with NIDDM. Accelerated gastric emptying in patients with nonneuropathic NIDDM is associated with increased proximal stomach phasic contractions.

Impairment of nitrergic-mediated relaxation of rat isolated duodenum by experimental diabetes

1. Diabetes mellitus is associated with changes in gastrointestinal motility. The effects of experimental diabetes, induced by streptozotocin administration to rats 3-4 weeks previously, on the nitric oxide (NO)-mediated (nitrergic) relaxation of the duodenum have now been investigated. 2. The non-adrenergic, non-cholinergic (NANC) relaxation of the isolated duodenum induced by nicotine (0.3-10 microM) or the nicotinic agonist, 1,1-dimethyl-4-phenylpiperazinium (DMPP; 10 microM) was inhibited by the NO synthase inhibitor, NG-nitro-L-arginine (3-100 microM). 3. This nitrergic relaxation induced by nicotine or DMPP of the duodenum from diabetic rats was substantially smaller than that of the tissue from control rats. 4. By contrast, the relaxation of the duodenum from diabetic rats to the NO donor, nitroprusside (0.3-10 microM) was similar to that of control tissue, whereas the relaxation to ATP (0.1-3 microM) was enhanced to a small but significant degree. 5. Incubation of duodenal tissue from control rats at 4 degrees C for 72 h, which leads to neuronal disruption, significantly attenuated the relaxation to nicotine or DMPP whereas the relaxation induced by nitroprusside or ATP was not affected. Comparable cold-storage did not affect the endothelium-dependent relaxation of rat aortic rings induced by acetylcholine (0.01-2 microM). 6. The calcium-dependent NO synthase activity in duodenal tissue, determined by the conversion of radiolabelled L-arginine to citrulline, was significantly reduced in cold-stored tissue and in tissue obtained from diabetic rats. 7. These findings in the rat duodenum indicate that a reduction in intestinal NO synthase activity is associated with an impairment of the NANC relaxation. A defect in the intestinal nitrergic innervation could thus contribute to the motility dysfunction observed in diabetes.

Antroduodenal motility and transpyloric fluid movement in patients with diabetes studied using duplex sonography

BACKGROUND/AIMS

To elucidate the relationship between diabetic autonomic neuropathy and gastrointestinal motility, antroduodenal motility was studied in patients with diabetes using duplex sonography.

METHODS

Antroduodenal motility, transpyloric fluid movement, and velocity curves of fluid flow were studied using duplex sonography in 32 patients with diabetes and 10 healthy subjects after their ingestion of a meat soup.

RESULTS

The frequency of antroduodenal coordination was significantly reduced in patients with diabetes with both early and definite autonomic neuropathy compared with healthy subjects (P < 0.05 and P < 0.01, respectively). The frequency and duration of end-cycle reflux episodes were also significantly reduced in patients with early and definite autonomic neuropathy compared with healthy subjects (P < 0.05 and P < 0.01, respectively). The frequency of end-cycle reflux episodes was closely correlated with the frequency of antroduodenal coordination in both healthy subjects (r = 0.859; P = 0.002) and patients with diabetes (r = 0.929; P = 0.0001). There was a significant correlation between fasting plasma glucose concentrations and the frequency of antroduodenal coordination in patients with diabetes (r = -0.361; P = 0.039).

CONCLUSIONS

These findings suggest that reduced frequency and duration of end-cycle reflux episodes may be an early indicator of diabetic gastroparesis that may be related mainly to autonomic neuropathy but also in part to acute hyperglycemia.