Current concepts in diabetic gastroparesis

Low-intensity pulsed ultrasound at ST36 improves the gastric motility by TNF-α/IKKβ/NF-κB signaling pathway in diabetic rats

BACKGROUND AND AIM

Low-intensity pulsed ultrasound (LIPUS) can effectively regulate the central and peripheral nervous system. However, whether LIPUS could act on acupuncture points to modulate the activity of peripheral nervous has rarely been studied. Our study aimed to investigate whether LIPUS at ST36 could improve gastric emptying in diabetic gastroparesis rats.

METHODS

Sprague-Dawley male rats were divided into three groups: control group (CON), diabetic gastroparesis group (DM), and diabetic gastroparesis LIPUS treated group (LIPUS). The body weight and blood glucose were recorded every week. Glucose tolerance, gastric emptying rate, and gastric motility were measured before and after treatment. Gastric motility was assessed by ultrasonic examination and Muscle strip experiment. The expression level of c-Kit was assessed by immunohistochemistry staining. Levels of TNF-α, p-NF-κB p-65, NF-κB p-65, and p-IKKβ, IKKβ were measured by western blot.

RESULTS

We reported LIPUS at an intensity of 0.88 W/cm2 exhibited significant differences in functional recovery of gastric delayed emptying in diabetic rats. Through ultrasound gastric motility functional testing and analysis of gastric antral smooth muscle strips indirectly and directly proved the effectiveness of LIPUS for the recovery of gastric delayed emptying. Pathological analysis and western blot indicated that the mechanism by which LIPUS applied to ST36 improved gastric motility may be partially attributed to the inhibition of the TNF-α/IKKβ/NF-κB signaling pathway, thereby rescuing the damaged interstitial cells of Cajal network.

CONCLUSION

LIPUS at ST36 improved the gastric motility and rescued the damaged networks of interstitial cells of Cajal. LIPUS may have a promising therapeutic potential for diabetic gastroparesis.

Electroacupuncture at ST36 Improve the Gastric Motility by Affecting Neurotransmitters in the Enteric Nervous System in Type 2 Diabetic Rats

Electroacupuncture (EA) can effectively relieve hyperglycemia and gastric emptying disorders in diabetic gastroparesis (DGP). However, the effect of EA on type 2 diabetes mellitus (T2DM) gastroparesis and its mechanism in the enteric nervous system (ENS) are rarely studied. We investigated the therapeutic effect of EA at ST36 and its effect on the main inhibitory and excitatory neurotransmitters in the ENS in DGP rats. Male Sprague-Dawley (SD) rats were fed a high-fat diet for 2 weeks and injected with streptozotocin (STZ) at 35 mg/kg to induce T2DM. T2DM rats were divided into the diabetic mellitus (DM) group and the EA group. The control (CON) group comprised normal rats without any intervention. EA treatment was started 6 weeks after the induction of DM and continued for 5 weeks. The body weight and food intake of the rats were recorded every week. Blood glucose, insulin, glucose tolerance, gastric emptying, and antral motility were measured after treatment. The expression of protein gene product 9.5 (PGP9.5), neuronal nitric oxide synthase (nNOS), and choline acetyltransferase (ChAT) in gastric antrum were quantified by western blotting and quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). The T2DM gastroparesis model was successfully established. EA treatment reduced the body weight, food intake, and blood glucose; improved glucose intolerance and insulin resistance; increased the gastric emptying rate, the mean antral pressure, and the amplitude of antral motility; and decreased the frequency of antral motility compared with those in the DM group. EA treatment increased the expression level of nNOS, ChAT, and PGP9.5 proteins, and nNOS and ChAT mRNA. The results suggested that EA at ST36 could ameliorate DGP, partly restore the damage to general neurons, and increase nNOS and ChAT in the gastric antrum. EA improved DGP partly via reducing the loss of inhibitory and excitatory neurotransmitters in the ENS.

Practical management approach to gastroparesis

Gastroparesis is a syndrome characterised by delayed gastric emptying in the absence of mechanical obstruction. Symptoms can include early satiety, abdominal pain, bloating, vomiting and regurgitation which cause significant morbidity in addition to nutritional deficits. There is a higher prevalence in diabetics and females, but the incidence in the Australian population has not been well studied. Management of gastroparesis involves investigating and correcting nutritional deficits, optimising glycaemic control and improving gastrointestinal motility. Symptom control in gastroparesis can be challenging. Nutritional deficits should be addressed initially through dietary modification. Enteral feeding is a second-line option when oral intake is insufficient. Home parenteral nutrition is rarely used, and only accessible through specialised clinics in the outpatient setting. Prokinetic medication classes that have been used include dopamine receptor antagonists, motilin receptor agonists, 5-HT₄ receptor agonists and ghrelin receptor agonists. Anti-emetic agents are often used for symptom control. Interventional treatments include gastric electrical stimulation, gastric per-oral endoscopic myotomy, feeding jejunostomy and gastrostomy/jejunstomy for gastric venting and enteral feeding. In this article we propose a framework to manage gastroparesis in Australia based on current evidence and available therapies.

Chronic pain in type 2 diabetic patients: a cross-sectional study in primary care setting

BACKGROUND

Although diabetes mellitus (DM) is often associated with painful neuropathic syndromes, a significant number of DM patients suffer from non-neuropathic (nociceptive) pain. Unfortunately, there is insufficient data on the epidemiology of nociceptive pain in DM patients and its effect on their quality of life.

OBJECTIVE

To characterize pain in type 2 DM patients, and assess its effect on their quality of life.

METHODS

The study population included 342 type 2 DM patients, 18 years of age and above (mean age 70.7 ± 9.7), who reported having pain. The study questionnaires included the Brief Pain Inventory (BPI), the S-LANSS scale to assess pain with neuropathic features, life impact, and socio-demographic data.

RESULTS

One hundred and fifty-five DM patients (46.5%) reported having pain of predominantly neuropathic origin. Almost 75% of patients with neuropathic pain were females, compared to 57.8% of patients with nociceptive pain (P = 0.002). More patients with neuropathic pain reported constant daily pain (57.6% vs. 42.4%, P < 0.0001), and worse pain during the night (53.3% vs. 46.7%, P = 0.045). The pain affected daily activities, walking capacity, and mood. Patients with neuropathic pain reported a greater negative effect of pain on their quality of life than those with nociceptive pain (41.0% vs. 15.3%, P < 0.0001).

CONCLUSION

The impact of neuropathic pain in DM patients is much more significant than nociceptive pain and affects their quality of life and daily function to a greater degree.

Systemic sclerosis--challenges for clinical practice

The management of patients with systemic sclerosis (SSc) can be challenging because disease-associated damage is often difficult to reverse and curative therapies are not yet available. Early identification and appropriate monitoring of patients with SSc is, therefore, critical so that active disease can be controlled and tissue damage prevented or delayed. However, early diagnosis of SSc is often difficult because the early clinical stages of the disease can be very similar to that of other autoimmune conditions. Screening for major organ manifestations of SSc, particularly interstitial lung disease, pulmonary hypertension, renal involvement and cardiac disease is a priority because involvement of these organs is associated with shorter life expectancies and early intervention might prevent disease progression. The prevention and management of digital ischaemia is also important as appropriate therapy often prevents substantial morbidity and functional loss. Treating gastrointestinal dysmotility can usually be managed using proton pump inhibitors and promotility agents, although in severe cases total parenteral nutrition is required. Calcinosis in patients with SSc is another common challenge that requires appropriate disease management and pain control. Each of these topics, which are relevant to both physicians and patients with SSc, are reviewed in further detail herein.

Inhibiting TRPA1 ion channel reduces loss of cutaneous nerve fiber function in diabetic animals: sustained activation of the TRPA1 channel contributes to the pathogenesis of peripheral diabetic neuropathy

Peripheral diabetic neuropathy (PDN) is a devastating complication of diabetes mellitus (DM). Here we test the hypothesis that the transient receptor potential ankyrin 1 (TRPA1) ion channel on primary afferent nerve fibers is involved in the pathogenesis of PDN, due to sustained activation by reactive compounds generated in DM. DM was induced by streptozotocin in rats that were treated daily for 28 days with a TRPA1 channel antagonist (Chembridge-5861528) or vehicle. Laser Doppler flow method was used for assessing axon reflex induced by intraplantar injection of a TRPA1 channel agonist (cinnamaldehyde) and immunohistochemistry to assess substance P-like innervation of the skin. In vitro calcium imaging and patch clamp were used to assess whether endogenous TRPA1 agonists (4-hydroxynonenal and methylglyoxal) generated in DM induce sustained activation of the TRPA1 channel. Axon reflex induced by a TRPA1 channel agonist in the plantar skin was suppressed and the number of substance P-like immunoreactive nerve fibers was decreased 4 weeks after induction of DM. Prolonged treatment with Chembridge-5861528 reduced the DM-induced attenuation of the cutaneous axon reflex and loss of substance P-like immunoreactive nerve fibers. Moreover, in vitro calcium imaging and patch clamp results indicated that reactive compounds generated in DM (4-hydroxynonenal and methylglyoxal) produced sustained activations of the TRPA1 channel, a prerequisite for adverse long-term effects. The results indicate that the TRPA1 channel exerts an important role in the pathogenesis of PDN. Blocking the TRPA1 channel provides a selective disease-modifying treatment of PDN.

The effects of weight loss strategies on gastric emptying and appetite control

The gastrointestinal tract plays an important role in the improved appetite control and weight loss in response to bariatric surgery. Other strategies which similarly alter gastrointestinal responses to food intake could contribute to successful weight management. The aim of this review is to discuss the effects of surgical, pharmacological and behavioural weight loss interventions on gastrointestinal targets of appetite control, including gastric emptying. Gastrointestinal peptides are also discussed because of their integrative relationship in appetite control. This review shows that different strategies exert diverse effects and there is no consensus on the optimal strategy for manipulating gastric emptying to improve appetite control. Emerging evidence from surgical procedures (e.g. sleeve gastrectomy and Roux-en-Y gastric bypass) suggests a faster emptying rate and earlier delivery of nutrients to the distal small intestine may improve appetite control. Energy restriction slows gastric emptying, while the effect of exercise-induced weight loss on gastric emptying remains to be established. The limited evidence suggests that chronic exercise is associated with faster gastric emptying, which we hypothesize will impact on appetite control and energy balance. Understanding how behavioural weight loss interventions (e.g. diet and exercise) alter gastrointestinal targets of appetite control may be important to improve their success in weight management.

Does grading the severity of gastroparesis based on scintigraphic gastric emptying predict the treatment outcome of patients with gastroparesis?

OBJECTIVES

The objectives of this study were as follows: (1) Whether gastric emptying is different between gastroparesis (GP) patients responding or not responding to standard medical therapy; (2) Identifying if mild, moderate, and severe degrees of gastroparesis based on the scintigraphic gastric emptying test (GET) can predict treatment responses for GP of diabetic (DM) and idiopathic (ID) origin.

METHODS

A total of 165 patients (119 F) diagnosed with GP [126 (76%) DM, 39 (24%) ID etiology] failed medical treatment and required the gastric electrical stimulation (GES) device (GES group). In addition, 112 patients (89 F) [37 (33%) DM, 75 (67%) ID] with GP who symptomatically responded to medical therapies are the comparison group (MED GP). All patients underwent a standardized scintigraphic GET consisting of low-fat (2%) isotope labeled egg beaters meal of 250 kcal. We also analyzed the GET data to find cut-off points for different degrees of GP and identified mild (11-20% retention), moderate (21-35%), and severe gastroparesis (>35%) based on percent retention of isotope at 4 h.

RESULTS

Overall gastric retention at 4 h was significantly greater in the GES group (45±1.9%) than MED GP (30±2%) (p<0.001). The distribution severity of the GET was different in GES-treated patients than MED treated (p<0.001). In the diabetics, 57% of GES patients retained >35% after 4 h (severe) similar to 43% in the DM MED group. However, 50% of the ID GES patients had retention>35% at 4 h significantly more than only 17% of ID MED GP. Significantly more ID patients who responded to medical therapy had mild gastroparesis and significantly more requiring GES had severe GET (p<0.05).

CONCLUSIONS

(1) GET in patients whose GP symptoms were refractory to standard medical therapy and required GES was significantly slower than in GP patients whose symptoms responded to medical therapy. (2) Stratifying GET into mild, moderate, and severe degrees of gastric retention does not predict whether a medical or surgical approach will be better to control the symptoms of diabetic GP but does correlate with treatment for the idiopathic GP subgroup.

Identification of novel metoclopramide metabolites in humans: in vitro and in vivo studies

Metoclopramide (MCP) is frequently used to treat gastroparesis. Previous studies have documented MCP metabolism, but systematic structural identification of metabolites has not been performed. The aim of this study was to better understand MCP metabolism in humans. For examination of in vivo metabolism, a single oral 20-mg MCP dose was administered to eight healthy male volunteers, followed by complete urine collection over 24 h. In vitro incubations were performed in human liver microsomes (HLM) to characterize metabolism via cytochromes P450 and UDP-glucuronosyltransferases and in human liver cytosol for metabolism via sulfotransferases. Urine and subcellular incubations were analyzed for MCP metabolites on a mass spectrometer with accurate mass measurement capability. Five MCP metabolites were detected in vivo, and five additional metabolites were detected in vitro. The five metabolites of MCP identified both in vitro and in vivo were an N-O-glucuronide (M1), an N-sulfate (M2), a des-ethyl metabolite (M3), a hydroxylated metabolite (M4), and an oxidative deaminated metabolite (M5). To our knowledge, metabolites M1 and M4 have not been reported previously. M2 urinary levels varied 22-fold and M3 levels varied 16-fold among eight subjects. In vitro studies in HLM revealed the following additional metabolites: two ether glucuronides (M6 and M8), possibly on the phenyl ring after oxidation, an N-glucuronide (M7), a carbamic acid (M9), and a nitro metabolite (M10). Metabolites M6 to M10 have not been reported previously. In conclusion, this study describes the identification of MCP metabolites in vivo and in vitro in humans.

Metabolic interactions between prokinetic agents domperidone and erythromycin: an in vitro analysis

This study examined in vitro interaction between domperidone and erythromycin. Both are prescribed for refractory gastroparesis. Domperidone is metabolized via human cytochrome P4503A4. Erythromycin is a CYP3A4 inhibitor. Incubations evaluated domperidone metabolite formation in human liver microsomes and recombinant CYP3A4. Concentration- and time-dependent inhibition of 500 microM domperidone was studied with 2.5-200 microM erythromycin over 10-40 min. Domperidone metabolite (5-hydroxy domperidone, M3) formation was inhibited by erythromycin in a concentration- and time-dependent manner. The K(I) estimate was 18.4 microM in human liver microsomes and 4.1 microM in CYP3A4. Using a model incorporating CYP3A4 hepatic and gut inhibition, in vitro estimates from human liver microsomes and CYP3A4 were used to predict in vivo AUCi/AUC ratios of 2.54 and 4.95, respectively. Significant inhibition of domperidone metabolism by erythromycin occurs. This predicts greater domperidone drug exposure when used with erythromycin. This important drug-drug interaction will be evaluated in future human studies.

Characteristics of gastric myoelectrical activity in diabetic patients

AIM: To investigate the gastric myoelectrical activity in diabetic patients in different stages.

METHODS: Fifty-four patients with DM were included in this study, 24 males and 30 females, with a mean age of 59.9 ± 11.6 years. The patients were divided into three groups: group I without both complications and upper gastrointestinal symptoms, group II with complications but without severe upper gastrointestinal symptoms, group III with both complications and severe upper gastrointestinal symptoms. EGG were performed30 minutes preprandial and 60 minutes postprandial.

RESULTS: A total of 74.1% diabetic patients had dysrythmia. In the fasting state, 46.3% had normogastria, 31.5% had bradygastria, and 14.8% had arrhythmia. In postprandial, 46.3% had normogastria, 31.5% had bradygastria, and 14.8% arrhythmia. The power ratio of postprandial and preprandial was elevated in group III compared to group I (1.07 ± 1.17 vs 0.93 ± 0.14, P = 0.022). There was a negative correlation between PR and satiety in group III (r = -0.535, P = 0.040).

CONCLUSION: Bradygastria is significantly more common during the entire period of recording. Different EGG presentations are seen in patients with DM in different conditions.

D-glucose modulates synaptic transmission from the central terminals of vagal afferent fibers

Experimental evidence suggests that glucose modulates gastric functions via vagally mediated effects. It is unclear whether glucose affects only peripheral vagal nerve activity or whether glucose also modulates vagal circuitry at the level of the brain stem. This study used whole cell patch-clamp recordings from neurons of the nucleus of the tractus solitarius (NTS) to assess whether acute variations in glucose modulates vagal brain stem neurocircuitry. Increasing D-glucose concentration induced a postsynaptic response in 40% of neurons; neither the response type (inward vs. outward current) nor response magnitude was altered in the presence of tetrodotoxin suggesting direct effects on the NTS neuronal membrane. In contrast, reducing d-glucose concentration induced a postsynaptic response (inward or outward current) in 54% of NTS neurons; tetrodotoxin abolished these responses, suggesting indirect sites of action. The frequency, but not amplitude, of spontaneous and miniature excitatory postsynaptic currents (EPSCs) was correlated with d-glucose concentration in 79% of neurons tested (n = 48). Prior surgical afferent rhizotomy abolished the ability of D-glucose to modulate spontaneous EPSC frequency, suggesting presynaptic actions at vagal afferent nerve terminals to modulate glutamatergic synaptic transmission. In experiments in which EPSCs were evoked via electrical stimulation of the tractus solitarius, EPSC amplitude correlated with D-glucose concentration. These effects were not mimicked by L-glucose, suggesting the involvement of glucose metabolism, not uptake, in the nerve terminal. These data suggest that the synaptic connections between vagal afferent nerve terminals and NTS neurons are a strong candidate for consideration as one of the sites where glucose-evoked changes in vagovagal reflexes occurs.

Effect of tegaserod on gastric emptying and the expression of ghrelin and substance P in diabetic rats

AIM: To investigate the effect of tegaserod on gastric emptying and the expression of ghrelin and substance P (SP) in diabetic rats, and to explore the therapeutic effect of tegaserod on diabetic gastroparesis and its possible mechanism.

METHODS: Fifty Wistar rats were randomly divided into five groups: a normal control group (NC group, n = 10), a diabetes mellitus group (DM group, n = 10), a low dose tegaserod-treated group (TEG-L group, n = 10), a moderate dose tegaserod-treated group (TEG-M group, n = 10) and a high dose tegaserod-treated group (TEG-H group, n = 10). Diabetes was induced by intraperitoneal injection of streptozotocin (STZ). After 8 weeks, tegaserod was administered by intraperitoneal injection at doses of 0.1 mg/kg, 0.5 mg/kg and 1 mg/kg in TEG-L, TEG-M and TEG-H groups, respectively, for 3 days. Gastric emptying was measured by intragastric administration of phenol red. The expression of ghrelin in the gastric mucosa and SP in the gastric antrum was detected by immunohistochemistry.

RESULTS: The staining intensities for ghrelin and SP in all TEG groups were significantly decreased compared with those in the NC group (ghrelin: 34.721 ± 6.759, 33.547 ± 6.255, 35.141 ± 5.987 vs 43.514 ± 5.323, P < 0.05, P < 0.01, P < 0.01; SP: 13.548 ± 1.078, 13.952 ± 1.246, 11.845 ± 1.567 vs 16.383 ± 2.275, all P < 0.01) and increased compared with the DM group (ghrelin: 26.626 ± 4.596, all P < 0.05; SP: 9.257 ± 1.636, all P < 0.01). However, the differences in ghrelin staining intensities among TEG groups were not statistically significant. The staining intensities for SP in the TEG-L and TEG-M groups were increased compared with the TEG-H group (both P < 0.05).

CONCLUSION: Tegaserod may improve delayed gastric emptying in diabetic rats by enhancing the expression and release of ghrelin and SP.

Estimation of influence of gastric emptying on shape of glucose concentration-time profile measured in oral glucose tolerance test

AIMS

To develop a model for simulations of processes in the oral glucose tolerance test (OGTT), using tools of the theory of dynamic systems.

METHODS

Frequent sampling OGTT was performed in 13 healthy subjects (6 males and 7 females). Subsequently, employing glucose and insulin concentration-time profiles of the subjects, the model was developed.

RESULTS

In all subjects the model was able to simulate influences of the insulin plasma concentration and gastric emptying rate on glucose concentration and to determine time profiles of glucose fractions retained in stomach.

CONCLUSIONS

The approach presented represents an opportunity for building models for data analyses in OGTT.

Tricyclic antidepressants for chronic vomiting in diabetic patients

Chronic vomiting in diabetic patients often is unresponsive to prokinetic agents and poorly explained by delayed gastric emptying or neuropathy. This retrospective study examines clinical response to tricyclic antidepressants, a treatment of reported benefit in nondiabetic patients with unexplained vomiting syndromes. Outcomes were studied in 24 diabetic outpatients who had been treated with tricyclic antidepressants specifically for nausea and vomiting after an unsatisfactory response to prokinetic therapy. Symptom patterns and treatment response were determined from chart review and telephone interview. Ten patients (42%) had recurrent, stereotypical vomiting episodes with symptom-free intervals suggesting cyclic vomiting syndrome; 14 (58%) had persistent symptoms. By chart review, at least moderate symptom response to tricyclic antidepressant treatment (median dosage, 50 mg/day) occurred in 88% of subjects, with complete or nearly complete resolution of symptoms in one-third. At follow-up interview, 77% self-reported at least moderate symptom improvement during therapy and 68% rated tricyclic antidepressants the most effective treatment received. Duration of diabetes, presence of neuropathy, and psychiatric status were not predictive of treatment outcome in multivariate analysis, but a cyclical symptom pattern attenuated antidepressant response (P< 0.05). In this retrospective review, the majority of diabetic patients with chronic vomiting and incomplete response to prokinetic therapy benefited from tricyclic antidepressants in low-dose, open-label regimens and rated them the most effective treatment received. This therapeutic option should be further studied in diabetic patients considering the morbidity of chronic vomiting in this population.

Hypomagnesemia in patients with type 2 diabetes

Hypomagnesemia has been reported to occur at an increased frequency among patients with type 2 diabetes compared with their counterparts without diabetes. Despite numerous reports linking hypomagnesemia to chronic diabetic complications, attention to this issue is poor among clinicians. This article reviews the literature on the metabolism of magnesium, incidence of hypomagnesemia in patients with type 2 diabetes, implicated contributing factors, and associated complications. Hypomagnesemia occurs at an incidence of 13.5 to 47.7% among patients with type 2 diabetes. Poor dietary intake, autonomic dysfunction, altered insulin metabolism, glomerular hyperfiltration, osmotic diuresis, recurrent metabolic acidosis, hypophosphatemia, and hypokalemia may be contributory. Hypomagnesemia has been linked to poor glycemic control, coronary artery diseases, hypertension, diabetic retinopathy, nephropathy, neuropathy, and foot ulcerations. The increased incidence of hypomagnesemia among patients with type 2 diabetes presumably is multifactorial. Because current data suggest adverse outcomes in association with hypomagnesemia, it is prudent to monitor magnesium routinely in this patient population and treat the condition whenever possible.

Ghrelin stimulates gastric emptying and hunger in normal-weight humans

CONTEXT

Ghrelin is produced primarily by enteroendocrine cells in the gastric mucosa and increases gastric emptying in patients with gastroparesis.

MAIN OBJECTIVE

The objective of the study was to evaluate the effect of ghrelin on gastric emptying, appetite, and postprandial hormone secretion in normal volunteers.

DESIGN

This was a randomized, double-blind, crossover study.

SUBJECTS

Subjects included normal human volunteers and patients with GH deficiency.

INTERVENTION

Intervention included saline or ghrelin (10 pmol/kg.min) infusion for 180 min after intake of a radioactively labeled omelette (310 kcal) or GH substitution in GH-deficient patients.

MAIN OUTCOME MEASURES

Measures consisted of gastric empty-ing parameters and postprandial plasma levels of ghrelin, cholecystokinin, glucagon-like peptide-1, peptide YY, and motilin.

RESULTS

The emptying rate was significantly faster for ghrelin (1.26 +/- 0.1% per minute), compared with saline (0.83% per minute) (P < 0.001). The lag phase (16.2 +/- 2.2 and 26.5 +/- 3.8 min) and half-emptying time (49.4 +/- 3.9 and 75.6 +/- 4.9 min) of solid gastric emptying were shorter during ghrelin infusion, compared with infusion of saline (P < 0.001). The postprandial peak in plasma concentration for cholecystokinin and glucagon-like peptide-1 occurred earlier and was higher during ghrelin infusion. There was no significant effect of ghrelin on plasma motilin or peptide YY. There was no difference in gastric emptying before and after GH substitution.

CONCLUSION

Our results demonstrate that ghrelin increases the gastric emptying rate in normal humans. The effect does not seem to be mediated via GH or motilin but may be mediated by the vagal nerve or directly on ghrelin receptors in the stomach. Ghrelin receptor agonists may have a role as prokinetic agents.

Upper gastrointestinal sensory-motor dysfunction in diabetes mellitus

Gastrointestinal (GI) sensory-motor abnormalities are common in patients with diabetes mellitus and may involve any part of the GI tract. Abnormalities are frequently sub-clinical, and fortunately only rarely do severe and life-threatening problems occur. The pathogenesis of abnormal upper GI sensory-motor function in diabetes is incompletely understood and is most likely multi-factorial of origin. Diabetic autonomic neuropathy as well as acute suboptimal control of diabetes has been shown to impair GI motor and sensory function. Morphological and biomechanical remodeling of the GI wall develops during the duration of diabetes, and may contribute to motor and sensory dysfunction. In this review sensory and motility disorders of the upper GI tract in diabetes is discussed; and the morphological changes and biomechanical remodeling related to the sensory-motor dysfunction is also addressed.

GDNF rescues hyperglycemia-induced diabetic enteric neuropathy through activation of the PI3K/Akt pathway

Diabetes can result in loss of enteric neurons and subsequent gastrointestinal complications. The mechanism of enteric neuronal loss in diabetes is not known. We examined the effects of hyperglycemia on enteric neuronal survival and the effects of glial cell line-derived neurotrophic factor (GDNF) on modulating this survival. Exposure of primary enteric neurons to 20 mM glucose (hyperglycemia) for 24 hours resulted in a significant increase in apoptosis compared with 5 mM glucose (normoglycemia). Exposure to 20 mM glucose resulted in decreased Akt phosphorylation and enhanced nuclear translocation of forkhead box O3a (FOXO3a). Treatment of enteric neurons with GDNF ameliorated these changes. In streptozotocin-induced diabetic mice, there was evidence of myenteric neuronal apoptosis and reduced Akt phosphorylation. Diabetic mice had loss of NADPH diaphorase-stained myenteric neurons, delayed gastric emptying, and increased intestinal transit time. The pathophysiological effects of hyperglycemia (apoptosis, reduced Akt phosphorylation, loss of inhibitory neurons, motility changes) were reversed in diabetic glial fibrillary acidic protein-GDNF (GFAP-GDNF) Tg mice. In conclusion, we demonstrate that hyperglycemia induces neuronal loss through a reduction in Akt-mediated survival signaling and that these effects are reversed by GDNF. GDNF may be a potential therapeutic target for the gastrointestinal motility disorders related to diabetes.

Gastroretentive dosage forms: Overview and special case of Helicobacter pylori

The challenge to develop efficient gastroretentive dosage forms began about 20 years ago, following the discovery of Helicobacter pylori by Warren and Marshall. In order to understand the real difficulty of increasing the gastric residence time of a dosage form, we have first summarized the important physiologic parameters, which act upon the gastric residence time. Afterwards, we have reviewed the different drug delivery systems designed until now, i.e. high-density, intragastric floating, expandable, superporous hydrogel, mucoadhesive and magnetic systems. Finally, we have focused on gastroretentive dosage forms especially designed against H. pylori, including specific targeting systems against this bacterium.

The hypothalamus–pituitary–ovary axis and type 1 diabetes mellitus: a mini review

A high prevalence of menstrual cycle and fertility disturbances has long been associated with diabetes mellitus. However, rationalization of the intrinsic mechanisms of these alterations is controversial and even contradictory. This review considers (i) the relationship between diabetes mellitus, especially type 1 diabetes mellitus (T1DM), and the hypothalamus-pituitary-ovary (HPO) axis, (ii) the state of our knowledge concerning neuroendocrine control and its relationship with dopaminergic and opioid tonus, and (iii) the influence of the hypothalamus-pituitary-adrenal axis on ovarian function. Functional disturbances that occur as a consequence of diabetes are also discussed, but some T1DM-related diseases of autoimmune origin, such as oophoritis, are not further analysed. Although there are clear indications of a relationship between menstrual and fertility alterations and glycaemic control, in many instances the improvement of the latter is not sufficient to reverse such alterations. It appears that the oligoamenorrhoea and amenorrhoea associated with T1DM is mainly of hypothalamic origin (i.e. failure of the GnRH pulse generator) and may be reversible. The importance of the evaluation of the HPO axis in T1DM women with menstrual irregularities, even in the presence of adequate metabolic control, is emphasized.

Simple and Noninvasive Breath Test Using 13C-Acetic Acid to Evaluate Gastric Emptying in Conscious Rats and Its Validation by Metoclopramide

The (13)C-breath test has been used to clinically evaluate gastric emptying. However, this method has not been sufficiently validated in experimental animals. The present study aimed to establish a simple and noninvasive (13)C-breath-test system in Sprague-Dawley male rats. After fasting, rats were orally administered Racol containing (13)C-acetic acid and housed in a desiccator. The expired air in the chamber was collected in a breath-sampling bag using a tube and aspiration pump. The level of (13)CO2 in the expired air was measured using an infrared spectrometer at appropriate intervals for 120 min. During this period, the rate of (13)CO2 excretion increased, peaked, and decreased thereafter. The maximum concentration (Cmax) and area under the curve (AUC120 min) of (13)CO2 excretion increased in volume- and dose-dependent manners. The time taken to reach the maximum concentration (Tmax) of (13)CO2 excretion increased as the volume increased, but was not affected by the dose of (13)C-labeled acetic acid. Metoclopramide dose-dependently increased the Cmax and shortened Tmax of (13)CO2 excretion compared with those of the control rats, whereas the AUC120 min was not affected. These results confirm that this simple method can successfully evaluate gastric emptying. Moreover, this system is suitable for investigating additional physiological functions using other labeled compounds.

Clinical issues in the care of critically ill diabetic patients

Critically ill patients with a preexisting diagnosis of diabetes mellitus are very common and they have several inherent disorders that make their ICU care challenging. There is increasing evidence that hyperglycemia is all too common in the critically ill and that improved glucose control at presentation and during an ICU stay improves mortality. Glucose control after acute myocardial infarction and coronary artery bypass grafting in particular affects patient outcome and mortality. Diabetic patients are more prone to several medical problems that can predispose them to critical illness, prolong hospitalization, and increase mortality. Delayed gastric emptying and altered metabolism that affect medication dosing, absorption, and efficacy are common in this population. In addition, many patients with diabetes have renal dysfunction that can cause difficulties with drug excretion and glucose monitoring. Finally, patients with diabetes have an increased rate and severity of life-threatening infections and venous thromboembolism than do patients with normal glucose metabolism. There are many treatment options for patients with diabetes, and hyperglycemia in the ICU should be corrected in order to avoid adverse outcomes.