Erythromycin improves glycaemic control in patients with Type II diabetes mellitus

Postprandial hypoglycemia caused by the combination of clarithromycin and rifampicin in a patient with nontuberculous mycobacterial pulmonary disease

Most cases of nontuberculous mycobacterial pulmonary disease (NTM-PD) have a progressive clinical course, and initiation of treatment is recommended rather than watchful waiting. The NTM-PD medications are frequently associated with adverse reactions, occasionally serious. Optimization of the methods for monitoring and managing adverse events in NTM-PD treatment is thus an important medical issue. Here we report a first case of postprandial hypoglycemia caused by the combination of clarithromycin (CAM) and rifampicin (RFP) in a patient with NTM-PD. A 73-year-old Japanese woman with NTM-PD was hospitalized for treatment with a combination of oral CAM, RFP, and ethambutol. She took the first doses of antibiotics before breakfast, and 3 h later went into a hypoglycemic state. Postprandial hypoglycemia occurred with high reproducibility and was accompanied by relative insulin excess. Continuous glucose monitoring with or without food and in combination with various patterns of medication revealed that the combination of CAM and RFP specifically induced postprandial hypoglycemia. Shifting the timing of administration of the CAM and RFP combination from morning to before sleep corrected the hypoglycemia and enabled continuation of the antimicrobial treatment. In conclusion, our report suggests the importance of introducing NTM-PD medication under inpatient management in order to closely monitor and early detect postprandial hypoglycemia and other serious adverse events.

Physiological functions and potential clinical applications of motilin

Motilin is a gastrointestinal hormone secreted by the duodenum. This peptide regulates a characteristic gastrointestinal contraction pattern, called the migrating motor complex, during the fasting state. Motilin also affects the pressure of the lower esophageal sphincter, gastric motility and gastric accommodation in the gastrointestinal tract. Furthermore, motilin induces bile discharge into the duodenum by promoting gallbladder contraction, pepsin secretion in the stomach, pancreatic juice and insulin secretion from the pancreas. In recent years, it has been shown that motilin is associated with appetite, and clinical applications are expected for diseases affected by food intake, e.g. obesity, by regulating motilin levels. Gastric acid and bile are the two major physiological regulators for motilin release. Caloric foods have varying effects on motilin levels, depending on their composition. Among non-caloric foods, bitter substances reduce motilin levels and are therefore expected to have an appetite-suppressing effect. Various motilin receptor agonists and antagonists have been developed but have yet to reach clinical use.

Motilin: a panoply of communications between the gut, brain, and pancreas

Introduction: Motilin was first alluded to nearly a century ago. But it remains a rather abstruse peptide, in the shadow of its younger but more lucid 'cousin' ghrelin.Areas covered: The review aimed to bring to the fore multifarious aspects of motilin research with a view to aiding prioritization of future studies on this gastrointestinal peptide.Expert opinion: Growing evidence indicates that rodents (mice, rats, guinea pigs) do not have functional motilin system and, hence, studies in these species are likely to have a minimal translational impact. Both the active peptide and motilin receptor were initially localized to the upper gastrointestinal tract only but more recently - also to the brain (in both humans and other mammals with functional motilin system). Motilin is now indisputably implicated in interdigestive contractile activity of the gastrointestinal tract (in particular, gastric phase III of the migrating motor complex). Beyond this role, evidence is building that there is a cross-talk between motilin system and the brain-pancreas axis, suggesting that motilin exerts not only contractile but also orexigenic and insulin secretagogue actions.

A Meta-Analysis of the Efficacy of Prokinetic Agents against Glycemic Control

Background

Prokinetic agents are used in diabetic gastroparesis patients to improve gastric emptying and upper gastrointestinal (GI) symptoms. However, the efficacy of prokinetic agents against glycemic control is questionable. Therefore, we conducted a systemic review and meta-analysis to determine the efficacy of prokinetic agents against glycemic control.

Methods

Randomized controlled trials (RCTs) evaluating the effect of prokinetics were identified by searching PubMed, Embase, and the Cochrane Library databases until April 2018. The primary outcome was changes in the mean value of glycosylated hemoglobin (HbA1c), fasting blood sugar (FBS), and fasting serum insulin (FINS). The pooled standardized mean differences (SMD) with 95% confidence intervals (CIs) were calculated by evaluating the strength of the association. We used the random effect models to analyze these markers. The effects of each component of the prokinetic agents on glycemic control were separately analyzed.

Results

Five RCTs with 190 patients met the criteria and were included in the meta-analysis. There were statistically significant SMD between prokinetics and placebo-controlled groups with respect to the reduction of HbA1c (-1.141, 95% CI -1.843, -0.438; P < 0.01). No statistically significant differences were noted between the two groups for FBS (-1.270, 95% CI -2.613, -0.074; P = 0.06) and FINS (0.359, 95% CI -1.205~1.923; P = 0.65).

Conclusions

Prokinetics have a positive effect on glycemic control. Further large-scale prospective studies are needed.

Motilin: from gastric motility stimulation to hunger signalling

After the discovery of motilin in 1972, motilin and the motilin receptor were studied intensely for their role in the control of gastrointestinal motility and as targets for treating hypomotility disorders. The genetic revolution - with the use of knockout models - sparked novel insights into the role of multiple peptides but contributed to a decline in interest in motilin, as this peptide and its receptor exist only as pseudogenes in rodents. The past 5 years have seen a major surge in interest in motilin, as a series of studies have shown its relevance in the control of hunger and regulation of food intake in humans in both health and disease. Luminal stimuli, such as bitter tastants, have been identified as modulators of motilin release, with effects on hunger and food intake. The current state of knowledge and potential implications for therapy are summarized in this Review.

The motilin agonist erythromycin increases hunger by modulating homeostatic and hedonic brain circuits in healthy women: a randomized, placebo-controlled study

The motilin agonist, erythromycin, induces gastric phase III of the migrating motor complex, which in turn generates hunger peaks. To identify the brain mechanisms underlying these orexigenic effects, 14 healthy women participated in a randomized, placebo-controlled crossover study. Functional magnetic resonance brain images were acquired for 50 minutes interprandially. Intravenous infusion of erythromycin (40 mg) or saline started 10 minutes after the start of scanning. Blood samples (for glucose and hormone levels) and hunger ratings were collected at fixed timepoints. Thirteen volunteers completed the study, without any adverse events. Brain regions involved in homeostatic and hedonic control of appetite and food intake responded to erythromycin, including pregenual anterior cingulate cortex, anterior insula cortex, orbitofrontal cortex, amygdala, caudate, pallidum and putamen bilaterally, right accumbens, hypothalamus, and midbrain. Octanoylated ghrelin levels decreased, whereas both glucose and insulin increased after erythromycin. Hunger were higher after erythromycin, and these differences covaried with the brain response in most of the abovementioned regions. The motilin agonist erythromycin increases hunger by modulating neurocircuitry related to homeostatic and hedonic control of appetite and feeding. These results confirm recent behavioural findings identifying motilin as a key orexigenic hormone in humans, and identify the brain mechanisms underlying its effect.

The pharmacodynamics, safety and pharmacokinetics of single doses of the motilin agonist, camicinal, in type 1 diabetes mellitus with slow gastric emptying

BACKGROUND AND PURPOSE

Here we have investigated the pharmacokinetics, pharmacodynamics and safety of single doses of camicinal in type 1 diabetes mellitus (T1DM) patients with a history of slow gastric emptying with symptoms consistent with gastroparesis.

EXPERIMENTAL APPROACH

In a randomized, double-blind, placebo-controlled, incomplete block, three-period, two-centre crossover study, patients received oral administration of placebo and two of the three possible doses of camicinal (25, 50 or 125 mg). Gastric emptying ((13) C-octanoic acid breath test), pharmacokinetics and safety were primary outcomes.

KEY RESULTS

Nine of the 10 patients enrolled completed the study. Gastric half-emptying time decreased by -95 min (95% CI: -156.8, -34.2) after a single dose of camicinal 125 mg compared with placebo (52 vs. 147 min, P < 0.05), representing a 65% improvement. A decrease of the gastric half-emptying time compared with placebo (approximately 39 min) was observed with camicinal 25 and 50 mg, representing a 27% reduction for both doses (not statistically significant). A positive exposure-response relationship was demonstrated across all doses. The effects of camicinal on gastric half-emptying time were not influenced by fasting glucose levels. Single doses up to 125 mg were well tolerated. Camicinal was well absorbed, exhibiting linear and approximately dose-proportional pharmacokinetic characteristics and a clear exposure-response relationship with gastric emptying.

CONCLUSIONS AND IMPLICATIONS

Camicinal significantly accelerated gastric emptying of solids in T1DM patients following administration of a single oral dose. Camicinal was well tolerated and exhibited similar pharmacokinetic characteristics in diabetic patients to those previously reported in healthy volunteers.

Mosapride citrate increases postprandial glucagon-like peptide-1, insulin, and gene expression of sweet taste receptors

BACKGROUND AND AIM

Mosapride citrate-a prokinetic agent-improves hemoglobin A1c levels in diabetic patients; however, the underlying mechanism is unclear. We aimed to clarify this mechanism.

METHODS

Preprandial and postprandial (90 min after a meal) blood was obtained from 12 healthy men, and serum insulin and plasma active glucagon-like peptide-1 concentrations were measured. Measurements were also taken after the administration of 5 mg of mosapride citrate three times per day after every meal for 14 days. In addition, C57BL/6 mice were permitted free access to water containing 0.04 % domperidone (D group) or 0.02 % mosapride citrate (M group) for 2 weeks (four mice per group). T1r2 (taste receptor, type 1, member 2), T1r3, and Gnat3 (guanine nucleotide-binding protein, alpha transducing 3) mRNA expression levels of the stomach, duodenum, and proximal and mid-jejunum were evaluated.

RESULTS

In human subjects, postprandial plasma active glucagon-like peptide-1 and serum insulin concentrations after administration of mosapride citrate were significantly higher than those pre-administration (4.8 ± 2.2 pmol/L, 45.6 ± 41.6 μIU/mL, and 3.7 ± 1.2 pmol/L, 34.1 ± 28.4 μIU/mL, respectively). The mouse expression levels of T1r2 and Gnat3 in the proximal jejunum and mid-jejunum in the M group (4.1 ± 1.8-fold, 3.1 ± 1.6-fold, and 4.6 ± 0.8-fold, 3.1 ± 0.9-fold increases, respectively), were significantly higher than those of the control group.

CONCLUSIONS

The administration of mosapride citrate for 2 weeks enhanced postprandial plasma active glucagon-like peptide-1 and serum insulin concentration and increased the expression of sweet taste receptors in the upper intestine.

Interaction of insulin with prokinetic drugs in STZ-induced diabetic mice

AIM: To study the possible interactions of metoclopramide, domperidone and erythromycin in streptozotocin-induced diabetic mice treated with insulin by various parameters.

METHODS: Effects of the individual as well as combined drugs were studied in diabetic mice via estimation of the blood glucose and serum insulin levels, small intestinal transit (SIT), gastric emptying (GE), xylose absorption and glucose tolerance tests. Groups were given insulin 2 IU/kg s.c., metoclopramide 20 mg/kg p.o., domperidone 20 mg/kg p.o. and erythromycin 6 mg/kg p.o. individually and in combination. There were also normal and diabetic control groups. The first set of experiments was carried out to investigate the subchronic effect on blood glucose and serum insulin levels in diabetic mice of one week of daily dose administration of the tested drugs individually as well as the combination of insulin with each prokinetic drug. The other five sets of experiments were carried out to investigate the acute effect of a single dose of each drug individually and in combination on blood glucose and serum insulin levels, SIT, GE, oral xylose absorption and glucose tolerance tests.

RESULTS: The study included the prokinetic drugs metoclopramide (20 mg/kg), domperidone (20 mg/kg) and erythromycin (6 mg/kg), as well as insulin (2 IU/kg), which was individually effective in decreasing SIT, enhancing GE and increasing xylose absorption significantly in diabetic mice. Erythromycin tended to decrease blood glucose level and increase serum insulin level after 1 wk of daily administration in diabetic mice. Erythromycin potentiated the effect of insulin on blood glucose level and serum insulin level whereas other prokinetic agents failed to do so after repeated dose administration in diabetic mice. Metoclopramide or erythromycin in combination with insulin significantly decreased SIT, in diabetic mice, to lower levels than with insulin alone. Administration of prokinetic drugs along with insulin antagonized the action of insulin on xylose absorption. These combinations also increased the rate of glucose absorption from the gut.

CONCLUSION: The present study suggests that prokinetic drugs could potentially improve glycemic control in diabetic gastroparesis by allowing a more predictable absorption of nutrients, matched to the action of exogenous insulin. The use of prokinetics, such as erythromycin, may be interesting in the clinic in decreasing the need for insulin in diabetic patients. The dose of insulin may be safely decreased with erythromycin in chronic treatments.

Motilin stimulates preadipocyte proliferation and differentiation and adipocyte lipid storage

Motilin is a circulating gastrointestinal peptide secreted primarily by duodenal mucosal M cells and recognized for its prokinetic effects on gastrointestinal tissues. Little information is available regarding effects on insulin/glucose homeostasis or adipocyte function. Our aim was to evaluate the effects of motilin on adipocyte proliferation, differentiation, lipolysis, and macronutrient uptake in adipocytes. 3T3-L1 cells and primary rat adipocytes were treated acutely and chronically with varying motilin concentrations, and effects were compared with vehicle alone (control), set as 100% for all assays. In preadipocytes, motilin stimulated proliferation ([(3)H]thymidine incorporation) and mitochondrial activity (141 ± 10%, P < 0.001 and 158 ± 10%, respectively, P < 0.001), in a concentration-dependent manner. Chronic supplementation with motilin during differentiation further increased lipogenesis (Oil red O staining 191 ± 27%, P < 0.05) and was associated with an upregulation of PPARγ (148 ± 8%, P < 0.01), C/EBPα (142 ± 17%, P < 0.05), and Cav3 (166 ± 20%, P < 0.05) expression. In mature 3T3-L1 adipocytes motilin increased fatty acid uptake/incorporation (≤ 202 ± 12%; P < 0.01) and glucose uptake (146 ± 9% P < 0.05) and decreased net fatty acid release (maximal -31%, P < 0.05) without influencing total lipolysis (glycerol release). Similar effects were obtained in primary rat adipocytes. Motilin acutely increased expression of PPARγ, CEBPβ, DGAT1, and CD36 while decreasing adiponectin mRNA and secretion. In human adipose tissue, motilin receptor GPR38 correlated with HOMA-IR and GHSR1 (r = 0.876, P < 0.0001). Motilin binding and fatty acid incorporation into adipocytes were inhibited by antagonists MB10 and [D-lys3]-GRP6 and PI 3-kinase inhibitor wortmannin. Taken together, these results suggest that motilin may directly influence adipocyte functions by stimulating energy storage.

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.

Luteolin reduces high glucose-mediated impairment of endothelium-dependent relaxation in rat aorta by reducing oxidative stress

While luteolin, a flavone rich in many plants, has some cardiovascular activity, it is not clear whether luteolin has beneficial effects on the vascular endothelial impairment in hyperglycemia/high glucose. Here, we reveal the protective effect of luteolin on endothelium-dependent relaxation in isolated rat aortic rings exposed to high glucose. The thoracic aorta of male Sprague-Dawley rats was rapidly dissected out and the effect of luteolin on the tension of aortic rings pretreated with high glucose (44mM) for 4h was measured in an organ bath system. The levels of nitric oxide (NO), hydroxy radical (OH(-)) and reactive oxygen species (ROS), and the activity of superoxide dismutase (SOD) and nitric oxide synthase (NOS) were measured in aortas. The vasorelaxation after treatment with luteolin for 8 weeks in aortic rings from diabetic rats was also determined. We found that exposure to high glucose decreased acetylcholine-induced endothelium-dependent relaxation. However, high mannitol had no effect on vasorelaxation. Luteolin evoked a concentration-dependent relaxation in aortic rings previously contracted by phenylephrine, and the pD(2) value was 5.24+/-0.04. The EC(50) of luteolin markedly attenuated the inhibition of relaxation induced by high glucose, which was significantly weakened by pretreatment with l-NAME (0.1mM), but not by indomethacin (0.01mM). Luteolin significantly inhibited the increase of ROS level and OH(-) formation, and the decrease of NO level, NOS and SOD activity caused by high glucose. The improving effect of luteolin on endothelium-dependent vasorelaxation in diabetic rat aortic rings was reversed by pretreatment with l-NAME or methylene blue. The results indicate that the decrease of endothelium-dependent relaxation in rat aortic rings exposed to high glucose is markedly attenuated by luteolin, which may be mediated by reducing oxidative stress and enhancing activity in the NOS-NO pathway.

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.

Gastroparesis in type 2 diabetes mellitus: prevalence, etiology, diagnosis, and treatment

The worldwide epidemic of type 2 diabetes mellitus (T2DM) is a substantial economic and social burden. Although gastroparesis associated with type 1 diabetes mellitus (T1DM) has been recognized for years, only recently have studies shown that patients with T2DM also have high rates of gastroparesis. Individuals with T2DM constitute 90% to 95% of the diabetic population. Unique characteristics that distinguish this population are obesity, insulin resistance, and associated comorbidities. These features highlight the importance of investigating gastric emptying in individuals with T2DM and upper gastrointestinal symptoms. The purpose of this review is to examine the literature pertaining to diabetes and the effect of diabetes on gastric neuromuscular function, with a focus on T2DM. An understanding of gastric motility in T2DM is important to diagnose gastroparesis, to treat upper gastrointestinal symptoms, and to restore normal gastric motility, which may lead, in turn, to improved glucose control.

Clinical trial: effect of mitemcinal (a motilin agonist) on gastric emptying in patients with gastroparesis - a randomized, multicentre, placebo-controlled study

BACKGROUND

Mitemcinal is an orally active motilin agonist that could potentially improve gastric emptying.

AIM

To investigate the effect of mitemcinal on gastric emptying in patients with idiopathic and diabetic gastroparesis.

METHODS

In a randomized, double-blind design, 106 patients were randomized into four dosing regimens (22 to placebo and 21 each to mitemcinal 10 mg, 20 mg, 30 mg bid or 20 mg tid) for 28 days. A standardized scintigraphic gastric emptying test was performed at screening and again after completing the 4-week protocol.

RESULTS

All doses of mitemcinal showed prokinetic activity. A significant improvement in meal retention at 240 min was noted even in the lowest dose group with the greatest improvement observed with 30 mg bid group (75% vs. 10% in placebo group). Diabetic patients responded better than the idiopathic subgroup. In diabetic patients, blood glucose at 1 h after a meal showed dose-dependent elevation. Although gastroparetic symptoms improved with both mitemcinal and placebo, the prominent placebo effect was not statistically exceeded by mitemcinal. Baseline scintigraphy results exhibited no clear correlation between the severity of gastroparetic symptoms and the status of gastric emptying.

CONCLUSION

Mitemcinal is capable of accelerating gastric emptying in both diabetic and idiopathic patients with gastroparesis.

Expression of motilin in the hypothalamus and the effect of central erythromycin on gastric motility in diabetic rats

OBJECTIVE

To investigate the expression of motilin-immunoreactive neurons in the hypothalamus and the effect of central administration of erythromycin (EM) on the regulation of gastric motility in diabetic rats.

METHODS

The motilin immunoreactive neurons in the hypothalamus and the hippocampus were detected by immunohistochemistry with rabbit anti-motilin polyclonal antibody. To measure the gastric motility, force transducers were surgically affixed to the gastric serosa. A microinjection syringe was connected via a plastic tube to an injection cannula, which was connected with a stainless steel guide cannula. The syringe was inserted into the right lateral cerebral ventricle for microinjecting the chemicals.

RESULTS

Diabetic mellitus was successfully induced in cohorts of rats. Motilin-immunoreactive neurons significantly increased in the paraventricular (PVN) and supraoptic nuclei (SON) of the hypothalamus in the diabetic rats. Intracerebroventricular (i.c.v.) administration of EM, a motilin receptor agonist, stimulated the gastric motility of diabetic rats. EM (91.56 nmol, i.c.v.) dose-dependently increased the amplitude by (174.82 +/- 48.62)% (P<0.05), and increased the frequency by (70.43 +/- 27.11)% (P < 0.05) in 5 min. The stimulatory effect lasted more than 15 min to the end of the measurement, and can be blocked partially by the prior treatment of motilin receptor antagonist GM-109.

CONCLUSION

Motilin-immunoreactive neurons are increased in the PVN and SON of the hypothalamus in diabetic rats. Centrally administered EM may regulate gastric motility by binding to the central motilin receptors, and central motilin might be involved in regulation of gastric motility in diabetic rats.

Erythromycin antagonizes the deceleration of gastric emptying by glucagon-like peptide 1 and unmasks its insulinotropic effect in healthy subjects

Glucagon-like peptide 1 (GLP-1) has been proposed to act as an incretin hormone due to its ability to enhance glucose-stimulated insulin secretion. Because GLP-1 also decelerates gastric emptying, it physiologically reduces rather than augments postprandial insulin secretory responses. Therefore, we aimed to antagonize the deceleration of gastric emptying by GLP-1 to study its effects on insulin secretion after a meal. Nine healthy male volunteers (age 25 +/- 4 years, BMI 25.0 +/- 4.9 kg/m2) were studied with an infusion of GLP-1 (0.8 pmol.kg(-1).min(-1) from -30 to 240 min) or placebo. On separate occasions, the prokinetic drugs metoclopramide (10 mg), domperidone (10 mg), cisapride (10 mg, all at -30 min per oral), or erythromycin (200 mg intravenously from -30 to -15 min) were administered in addition to GLP-1. A liquid test meal (50 g sucrose and 8% mixed amino acids in 400 ml) was administered at 0 min. Capillary and venous blood samples were drawn for the determination of glucose (glucose oxidase), insulin, C-peptide, GLP-1, glucagon, gastric inhibitory polypeptide (GIP), and pancreatic polypeptide (specific immunoassays). Gastric emptying was assessed by the phenol red dilution technique. Statistical analyses were performed using repeated-measures ANOVA and Duncan's post hoc test. GLP-1 significantly decelerated the velocity of gastric emptying (P < 0.001). This was completely counterbalanced by erythromycin, whereas the other prokinetic drugs used had no effect. Postprandial glucose concentrations were lowered by GLP-1 (P < 0.001 vs. placebo), but this effect was partially reversed by erythromycin (P < 0.05). Insulin secretory responses to the meal were lower during GLP-1 administration (P < 0.05 vs. placebo). However, when erythromycin was added to GLP-1, insulin concentrations were similar to those in placebo experiments. The suppression of meal-related increments in glucagon secretion by GLP-1 was reversed by erythromycin (P < 0.001). The time course of GIP secretion was delayed during GLP-1 administration (P < 0.05), but when erythromycin was added, the pattern was similar to placebo experiments. GLP-1 administration led to a reduction in pancreatic polypeptide plasma concentrations (P < 0.05). In contrast, pancreatic polypeptide levels were markedly increased by erythromycin (P < 0.001). Intravenous erythromycin counteracts the deceleration of gastric emptying caused by GLP-1, probably by interacting with the parasympathetic nervous system (pancreatic polypeptide responses). Despite augmented rises in insulin secretion, the glucose-lowering effect of GLP-1 is markedly reduced when the deceleration of gastric emptying is antagonized, illustrating the importance of this facet of the multiple antidiabetic actions of GLP-1.

American Gastroenterological Association technical review on the diagnosis and treatment of gastroparesis

This literature review and the recommendations herein were prepared for the American Gastroenterological Association Clinical Practice Committee. The paper was approved by the Committee on May 16, 2004, and by the AGA Governing Board on September 23, 2004.

Novel insulin-releasing peptides in the skin of Phyllomedusa trinitatis frog include 28 amino acid peptide from dermaseptin BIV precursor

OBJECTIVE

The granular glands of amphibians have long been known to produce many biologically active compounds. The aim of this study was to isolate and characterize insulinotropic peptides from the skin of Phyllomedusa trinitatis frog.

METHODS AND RESULTS

Crude secretions obtained by mild electrical stimulation of the dorsal skin surface were purified by reverse phase HPLC yielding 80 fractions. In acute incubations with glucose-responsive BRIN-BD11 cells, fractions 39-40 (band 1) and fractions 43-46 (band 2) significantly stimulated insulin release by 1.5 to 2.5-fold. Pooled fractions in bands 1 and 2 were rechromatographed to 4 homogeneous peaks, each with insulin-releasing activity. Mass spectrometry analysis was successfully completed for 3 peptides, indicating 2996.4, 3379.9, and 8326.4 Da. The sequence of the 2996.4 Da peptide was determined as ALWKDILKNVGKAAGKAVLNTVTDMVNQ. This 28-amino-acid peptide has 100% homology with the C-terminal of the 75-amino-acid dermaseptin BIV precursor of a family of structurally related antimicrobial peptides in the skin of the Phyllomedusinae subfamily.

CONCLUSION

These data demonstrate that the defensive skin secretions of P. trinitatis contain biologically active peptides, which may have mammalian counterparts and merit further investigation as insulin secretagogues.

Effects of erythromycin on colon dys-motility and neuroendocrine peptides in diabetic mellitus

AIM: To investigate the effects of erythromycin on contractive activity of isolated proximal colon smooth muscle and the change of somatostatin, vasoactive intestinal peptide, motilin and substance P in diabetic mellitus rats.

METHODS: Thirty male Sprague-Dawley rats were divided into three groups: the control (n = 10), the diabetic (n = 10) and erythromycin (n = 10). The resting tension, the mean contractile amplitude and frequency of spontaneous changes of isolated longitudinal, circular proximal colon smooth muscle strips were measured by transducer, and somatostatin, vasoactive intestinal peptide, motilin, substance P levels in plasma and proximal colon tissue extracts were measured by radioimmunoassay.

RESULTS: In isolated proximal colon smooth muscle strips, the motility parameters were significantly lower in diabetic rats than those in control (P < 0.01). After taking erythromycin, the colon motility parameters were significantly strengthened compared with those in diabetic rats (P < 0.01). In diabetic rats, the plasma levels of somatostatin, vasoactive intestinal peptide and motilin were higher than those in control (P < 0.05), while substance P level was decreased (P < 0.05). In the proximal colon, the levels of somatostatin and vasoactive intestinal peptide were significantly lower than that in control (P < 0.01, P < 0.05), the level of substance P was higher than that in the control (P < 0.05), and the level of motilin did not differ from that in the control (P > 0.05). After taking erythromycin, the plasma level of somatostatin was higher than that in diabetic rats (P < 0.05). The serum glucose was decreased in diabetic rats after erythromycin treatment (P < 0.01).

CONCLUSION: Erythromycin has direct effect on colon smooth muscle, and has little effect on neuroendocrine peptides. Colonic motility disorders in diabetes rats are related with the changes of neuroendocrine peptides levels in plasma and colon tissue.

Current concepts in diabetic gastroparesis

Diabetic gastroparesis is a common and debilitating condition affecting millions of patients with diabetes mellitus worldwide. Although gastroparesis in diabetes has been known clinically for more than 50 years, treatment options remain very limited. Until recently, the scientific literature has offered few clues regarding the precise aetiology of gastric dysfunction in diabetes.Up to 50% of patients with diabetes may experience postprandial abdominal pain, nausea, vomiting and bloating secondary to gastric dysfunction. There is no clear association between length of disease and the onset of delayed gastric emptying. Gastroparesis affects both type 1 (insulin dependent) and type 2 (non- insulin dependent) forms of diabetes. Diagnosis requires identifying the proper symptom complex, while excluding other entities (peptic ulcer disease, rheumatological diseases, medication effects). The diagnosis of gastroparesis may be confirmed by demonstrating gastric emptying delay during a 4-hour scintigraphic study. Treatment options are limited and rely on dietary modifications, judicious use of available pharmacological agents, and occasionally surgical or endoscopic placement of gastrostomies or jejunostomies. Gastric pacing offers promise for patients with medically refractory gastroparesis but awaits further investigation. Current pharmacological agents for treating gastroparesis include metoclopramide, erythromycin, cisapride (only available via a company-sponsored programme) and domperidone (not US FDA approved). All of these drugs act as promotility agents that increase the number or the intensity of gastric contractions. These medications are not uniformly effective and all have adverse effects that limit their use. Cisapride has been removed from the open market as a result of over 200 reported cases of cardiac toxicity attributed to its use. Unfortunately, there is a paucity of clinical studies that clearly define the efficacy of these agents in diabetic gastroparesis and there are no studies that compare these drugs to each other. The molecular pathophysiology of diabetic gastroparesis is unknown, limiting the development of rational therapies. New studies, primarily in animals, point to a defect in the enteric nervous system as a major molecular cause of abnormal gastric motility in diabetes. This defect is characterised by a loss of nitric oxide signals from nerves to muscles in the gut resulting in delayed gastric emptying. Novel therapies designed to augment nitric oxide signalling are being studied.

Nutrition therapy for diabetic gastroparesis

The management of diabetic gastroparesis often represents a significant clinical challenge in which the maintenance of nutrition is pivotal. Gastric emptying is delayed in 30% to 50% of patients with longstanding type 1 or type 2 diabetes and upper gastrointestinal symptoms also occur frequently. However, there is only a weak association between the presence of symptoms and delayed gastric emptying. Acute changes in blood glucose concentrations affect gastric motility in diabetes; hyperglycemia slows gastric emptying whereas hypoglycemia may accelerate it; blood glucose concentrations may also influence symptoms. It is now recognized that gastric emptying is a major determinant of postprandial glycemia and, therefore, there is considerable interest in the concept of modulating gastric emptying, by dietary or pharmacologic means, to optimize glycemic control in diabetes.

Effect of mosapride on glycemic control and gastric emptying in type 2 diabetes mellitus patients with gastropathy

Delay of gastric emptying is one of the factors responsible for unfavorable glycemic control. We investigated the possible effects of mosapride, a digestive tract prokinetic agent, on glycemic control in diabetic patients complicated with gastropathy. Enrolled were 36 type II diabetic patients presenting with mild digestive tract symptoms. They were given mosapride 15 mg per day for 6 months. Seventeen cases were subjected to gastric emptying test according to marker method (administration of a capsule containing 20 pieces of radiopaque marker during breakfast, followed by abdominal X-ray imaging 3 and 5 h later). In 18 cases, HbA(1C) was improved by more than 0.3% for 6 months, whereby these 18 cases were defined as the improvement group. The remaining 18 cases were defined as the non-improvement group. In the gastric emptying study, basal number of the residual markers before administration of mosapride was determined 3 and 5 h later to show 18.3+/-1.8 and 7.6+/-5.1, respectively, in the improvement group while after administration, they were reduced down to 11.2+/-5.1 and 1.4+/-2.5, respectively. In sharp contrast, the basal counterparts in the non-improvement group were 19.1+/-1.5, and 16.4+/-3.4, respectively, whereas administration failed to reduce the number of the residual markers and they remained to be as high as 19.0+/-1.4 and 11.1+/-6.4, respectively. Gastric motility in the improvement group was much more improved by mosapride administration relative to those in the non-improvement group. Mosapride might elicit improvement in the glycemic control in the patients with diabetic gastropathy.

Diagnosis and treatment of chronic gastroparesis and chronic intestinal pseudo-obstruction

Chronic gastroparesis and CIP are debilitating disorders that are difficult to treat with currently available therapies. Failure of proper migration and differentiation of enteric neurons or ICC can result from specific genetic mutations and lead to phenotypes of CIP with or without concomitant gastroparesis. Intestinal dysfunction in diabetes may reflect a depletion of NO production (and perhaps other neurotransmitters or modulators), which is manifest as a syndrome of gastroparesis, diarrhea, or constipation in individual patients. As the key molecular changes underlying these disorders are defined, clinicians will begin to understand their precise etiology and rational medical therapy may become possible. In the future, testable hypotheses regarding the etiology of other functional bowel disorders (e.g., functional dyspepsia, irritable bowel syndrome, and so forth) may be developed.

Effect of altering gastric emptying on postprandial plasma glucose concentrations following a physiologic meal in type-II diabetic patients

The purpose of this study was to determine the effects of altering gastric emptying on postprandial plasma glucose concentration after a physiologic meal in patients with type II diabetes mellitus (T II DM). Nine T II DM patients underwent a double-blind, randomized, three-way crossover study, receiving erythromycin 200 mg, morphine 8 mg, or normal saline (placebo) intravenously prior to ingestion of a radiolabeled, dual-isotope, solid-liquid meal. Gastric emptying of solids and liquids and serial plasma glucose, glucagon, and serum insulin concentrations were measured at baseline and for 5 hr after meal ingestion. Erythromycin accelerated and morphine delayed solid- and liquid-phase gastric emptying compared to placebo (P < 0.05). During the first hour, the postprandial plasma glucose concentrations were higher after erythromycin (P < 0.05) and lower after morphine (P < 0.05) compared to placebo. The peak postprandial plasma glucose concentration was higher after erythromycin (P = 0.05) and lower after morphine (P < 0.05) compared to placebo. In conclusion, pharmacologic acceleration of gastric emptying resulted in higher postprandial glucose concentrations, while delaying gastric emptying resulted in lower postprandial glucose concentrations after a physiologic meal in T II DM. These results suggest that administration of opiate analgesics or prokinetic agents to diabetic patients may alter glucose control. Modifying gastric emptying may be helpful in achieving glucose control in T II DM.

Gastric emptying in diabetes: clinical significance and treatment

The outcome of recent studies has led to redefinition of concepts relating to the prevalence, pathogenesis and clinical significance of disordered gastric emptying in patients with diabetes mellitus. The use of scintigraphic techniques has established that gastric emptying is abnormally slow in approx. 30-50% of outpatients with long-standing Type 1 or Type 2 diabetes, although the magnitude of this delay is modest in many cases. Upper gastrointestinal symptoms occur frequently and affect quality of life adversely in patients with diabetes, although the relationship between symptoms and the rate of gastric emptying is weak. Acute changes in blood glucose concentration affect both gastric motor function and upper gastrointestinal symptoms. Gastric emptying is slower during hyperglycaemia when compared with euglycaemia and accelerated during hypoglycaemia. The blood glucose concentration may influence the response to prokinetic drugs. Conversely, the rate of gastric emptying is a major determinant of post-prandial glycaemic excursions in healthy subjects, as well as in Type 1 and Type 2 patients. A number of therapies currently in development are designed to improve post-prandial glycaemic control by modulating the rate of delivery of nutrients to the small intestine.

Potential new treatments for type 2 diabetes

The heterogeneous pathogenesis and progressive natural history of type 2 diabetes mellitus (T2DM) contrive a formidable therapeutic challenge. Dual endocrine deficits of impaired insulin action (insulin resistance) and inadequate insulin secretion create an environment of chronic hyperglycaemia and general metabolic disarray. This inflicts a heavy burden of morbidity and premature mortality from cardiovascular diseases, microvascular disorders (e.g. retinopathy and nephropathy) and neuropathic conditions. Improving glycaemic control delays the onset and reduces the severity of these long-term complications. However, even with intensive use of current antidiabetic agents more than 50% of T2DM patients suffer poor glycaemic control and 18% develop serious complications within six years of diagnosis. Clearly, there is a need for new antidiabetic agents.