The Effect of Sodium Channel Blocker, Mexiletine, on Body Weight in Type 2 Diabetes Patients with Visceral Obesity.

OBJECTIVE: Mexiletine is an anti-arrhythmic agent also used for the treatment of painful diabetic neuropathy. In this study, the effect of mexiletine on body weight was evaluated in type 2 diabetes patients with diabetic neuropathy exhibiting visceral obesity. METHODS: Type 2 diabetes patients with neuropathy exhibiting visceral obesity (n = 21) treated by mexiletine (300 mg/day) and a control group of type 2 diabetes patients with the same condition who received vitamin B12 (n = 12) were retrospectively evaluated. Body weight, waist circumference, hemoglobin A1c (HbA1c), blood pressure, liver function, serum lipids, and serum uric acid were assessed before and 6 months after the treatment. RESULTS: Mexiletine significantly decreased body weight and waist circumference. The changes in body weight and waist circumference in 6 months in the mexiletine group were greater than in the control group. In metabolic parameters, there were significant decreases in triglyceride (TG) and serum uric acid. There were positive relationships between the change in body weight and the changes in TG, uric acid, alanine aminotransferase (ALT), and HbA1c. CONCLUSIONS: Mexiletine may affect body weight regulation. It ameliorated the metabolic parameters possibly by decreasing visceral fat. Further study should be performed to clarify the mechanism of the effect.

Urate-Lowering Therapy Ameliorates Kidney Function in Type 2 Diabetes Patients With Hyperuricemia.

BACKGROUND: Hyperuricemia often causes kidney dysfunction which increases serum urate, forming a vicious cycle in the kidney. In this study, urate-lowering therapy was demonstrated in type 2 diabetic patients with hyperuricemia to evaluate the effect on diabetic nephropathy. METHODS: Type 2 diabetic patients with hyperuricemia (n = 34) were treated by urate-lowering drugs. Serum urate levels, estimated glomerular filtration rate (eGFR), blood pressure, HbA1c, and urinary albumin-to-creatinine ratio (UACR) were measured for 52 weeks. The parameters at the endpoint when serum urate decreased to below 6.0 mg/dL and at 52 weeks were compared to the initial levels at week 0. RESULTS: Serum urate level decreased to the endpoint in all patients and was maintained at under 6.0 mg/dL throughout the observation period. eGFR significantly increased at the endpoint and also at 52 weeks. Overall UACR did not change after 52 weeks; however, the treatment decreased UACR significantly in patients with no microalbuminuria. There was a negative relationship between the change of serum urate levels and the change of eGFR, and a negative relationship between the baseline UACR and the change of UACR when patients with macroalbuminuria were excluded. There were no changes in HbA1c levels and blood pressure before and after the treatment. CONCLUSIONS: There were significant improvements in kidney function by lowering serum urate levels to under 6.0 mg/dL and the effect was maintained for at least 52 weeks. This treatment may be one strategy to slow the progression of nephropathy in type 2 diabetic patients with hyperuricemia.

The enhanced effect of atenolol on hypertension in metabolic syndrome.

BACKGROUND: In metabolic syndrome, hypertension has been noted as one of the most important risk factors that contributes to cardiovascular disease. We have evaluated the effect of a selective adrenergic ß(1)-receptor blocker, atenolol, on blood pressure and pulse rate in metabolic syndrome. METHODS: Metabolic syndrome patients with hypertension (n=28) and a control group (n=20) were given atenolol (50 mg/day) for 4 weeks. Blood pressure, pulse rate, and blood biochemical parameters were monitored. RESULTS: Pulse rate in the metabolic syndrome group before the treatment was significantly higher than in the control group (control 74 ± 2/min, metabolic syndrome 84 ± 2/min, P<0.05). Decrease in pulse rate resulting from the treatment was greater in the metabolic syndrome group than in the control group (control 14 ± 3/min, metabolic syndrome 21 ± 2/min, P<0.05). Decrease in systolic (SBP) and diastolic (DBP) blood pressure was greater in the metabolic syndrome group than in the control group (SBP, control 8 ± 3, metabolic syndrome 23 ± 3 mmHg, P<0.05; DBP, control 6 ± 3, metabolic syndrome 13 ± 2 mmHg, P<0.05). There was a positive association between decrease in SBP and the waist measurements of patients, between the decrease in DBP and the waist measurements, and between the decrease in pulse rate and the waist measurements. We also found that there was a positive association between the decrease in SBP and initial SBP, between the decrease in DBP and initial DBP, and between the decrease in pulse rate and initial pulse rate. CONCLUSIONS: These data showed that atenolol has an enhanced effect on blood pressure and on pulse rate in metabolic syndrome. It may be useful in treating severe hypertension with elevated heart rate in metabolic syndrome.

The effect of mosapride citrate on constipation in patients with diabetes.

OBJECTIVE: Constipation is one of the most common gastrointestinal complications suspected to degrade the quality of life in diabetic patients. Mosapride citrate is a novel selective 5-HT4 receptor agonist, which enhances gastric emptying and motility in the upper gastrointestinal tract facilitating acetylcholine release from the enteric cholinergic neurons. Since the receptors of 5-HT4 have been recently found in the lower intestine including the rectum in humans, we tested if mosapride improves constipation in diabetic patients. PATIENTS AND METHODS: Diabetic patients with constipation were treated with mosapride citrate (15 mg/day, n=20) or domperidone (30 mg/day, n=12) as controls for 8 weeks. Bowel frequency was monitored and gastrointestinal symptoms were evaluated by Gastrointestinal Symptoms Rating Scale (GSRS). RESULTS: Administration of mosapride resulted in increased bowel frequency after 4 and 8 weeks of administration, while no change was seen in the control group. Mosapride increased bowel frequency in even patients with diabetic polyneuropathy. Mosapride improved reflux and constipation evaluated by GSRS. As previously reported, glycemic control also improved by mosapride in these patients. CONCLUSIONS: Administration of mosapride increased bowel frequency and ameliorated symptoms of reflux and constipation possibly stimulating the lower intestine. Given that mosapride has those beneficial aspects, it may be a useful prokinetic agent in treating diabetic patients with constipation.

Central leptin gene therapy, a substitute for insulin therapy to ameliorate hyperglycemia and hyperphagia, and promote survival in insulin-deficient diabetic mice.

Long-term benefits of central leptin gene therapy in insulin-deficient diabetes are not known despite its therapeutic effects in obesity animal models such as ob/ob and diet-induced obese mice. Adult male mice were injected intraperitoneally with streptozotocin (STZ, 200mg/kg) to induce insulitis. A week later, only diabetic STZ-pretreated mice (blood glucose >350 mg/dl) received intracerebroventricularly (icv) an injection of recombinant adeno-associated virus vector (rAAV) encoding either green fluorescent protein (control), or leptin gene (rAAV-lep). Body weight (BW), food intake, blood glucose, insulin and survival rate responses were monitored post-icv injection at regular intervals for 52 weeks. The STZ pre-injected diabetic mice remained hyperphagic, gradually lost BW and died by week 6 after receiving control vector. In marked contrast, injection of rAAV-lep to raise hypothalamic leptin levels, rescued the STZ-pretreated mice from early mortality, gradually curbed hyperphagia to normalize intake by week 20, and maintained BW at significantly lower than the control range. Blood glucose levels in these mice started to recede dramatically by week 2-3 to normalize by week 8, and euglycemia was sustained during the remaining course of the experiment. rAAV-lep injected mice did not exhibit any discernible untoward gross behavioral changes and diabetic complications and showed a partial return of pancreatic beta-cell function. These results show for the first time that one time central leptin gene therapy is effective and durable in reinstating euglycemia and energy homeostasis for extended periods in the absence of insulin.

Blunted metabolic response to fasting in obese mice.

The aim of the study was to evaluate metabolic changes in response to fasting in normal and obese mice. C57BL6 and obese (diet-induced obesity (DIO) and ob/ob) mice were used in this study. They were fasted for 24 h and re-fed for 24 h. Body weight was monitored before, after fasting and during re-feeding (2 and 24 h after re-feeding). Food intake was measured 2 and 24 h after re-feeding began. Blood samples were taken before and after 24 h fasting. As metabolic parameters, blood glucose, plasma insulin, ghrelin levels and oxygen consumption were measured. Blood glucose and plasma insulin levels in DIO and ob/ob mice were higher than normal mice, and plasma ghrelin levels were lower in DIO and ob/ob mice. There was reduced body weight loss in DIO mice than in normal mice for 24 h fasting. When they were re-fed, DIO and ob/ob mice consumed less food intake than normal mice. Twenty-four hours food deprivation induced significantly smaller plasma ghrelin elevation in these obese mice. Fasting-induced decrease in oxygen consumption was significantly smaller in DIO and ob/ob mice than normal mice. This data show that obese mice may have decreased sensitivity to fasting-induced increase in circulating ghrelin and their oxygen consumption exhibited a blunted response to fasting.

Gastrointestinal hormones (anorexigenic peptide YY and orexigenic ghrelin) influence neural tube development.

Gastrointestinal (GI) hormones play an important role in GI secretion, motility, and eating behaviors. It was recently suggested that GI hormones may have a trophic role in GI tract. Here we demonstrate that two principal GI hormones, anorexigenic peptide YY (PYY) and orexigenic ghrelin, affect neural tube development. Chronic administration into the pregnant mice or transgenic overexpression of PYY led to a neural tube defect (NTD) in the embryos that was blocked by ghrelin. PYY Y1 receptor antagonist prevented the occurrence of NTD induced not only by PYY but also by vitamin A, a well-known teratogen in humans and animals. Y1 receptor deficiency also engendered NTDs, indicating the need to maintain normal Y1 receptor signaling. The present study is the first linking GI hormones to the leading cause of infant mortality and provides a novel insight for neurogenesis in which materno-fetal communication through GI hormones appears to be important.

Increased circulating cholecystokinin contributes to anorexia and anxiety behavior in mice overexpressing pancreatic polypeptide.

We have previously reported that pancreatic polypeptide (PP) overexpressing mice display thin phenotype with delayed gastric emptying and decreased food intake. In the present study, we further examined if CCK contributes to anorexia and anxiety behavior in PP overexpressing mice. Plasma CCK levels in PP overexpressing mice and their littermates were determined by radioimmunoassay using antisera specific to sulfated CCK-8 and CCK-33. To elucidate the role of CCK in PP overexpressing mice, CCK-1 receptor antagonist (L-364,718) or saline was administered intraperitoneally and food intake was measured for 2 h. CCK-2 antagonist (L-365,260) or saline was injected intraperitoneally and the elevated plus-maze test was performed to assess anxiety. Plasma CCK levels were significantly increased in PP overexpressing mice. Administration of L-364,718 increased food intake in PP overexpressing mice compared to the saline-injected PP overexpressing group, while L-364,718 did not increase food intake in non-transgenic littermates. PP overexpressing mice exhibited anxiety in the plus-maze test. Administration of CCK-2 receptor antagonist (L-365,260) reversed the decreased percentage of entry into the open arms in PP overexpressing mice. These results indicated that elevated CCK may contribute to anorexic and anxious phenotype of PP overexpressing mice.

A role for pancreatic polypeptide in feeding and body weight regulation.

PP administration induces negative energy balance by suppressing food intake and gastric emptying while increasing energy expenditure in rodents. The mechanism of PP actions involves the changes in the expression of hypothalamic feeding-regulatory peptides and the activity of the vago-vagal and vago-sympathetic reflex arc. PP-overexpressing mice we developed exhibited the thin phenotype with decreased food intake and gastric emptying rate. Plasma cholecystokinin (CCK) concentrations were increased in the transgenic mice and CCK-1 receptor antagonist improved the anorexia of the animals. These results, together with the previous notion of PP as an anti-CCK hormone in pancreatic exocrine secretion and gallbladder contraction, indicate that PP-CCK interactions may be either antagonistic or synergistic and the transgenic mice may exhibit the mixed phenotype by overproduction of PP and CCK.

Leptin gene transfer in the hypothalamus enhances longevity in adult monogenic mutant mice in the absence of circulating leptin.

Leptin, a product of the ob gene, is a pleiotropic signal implicated in regulation of multiple physiological functions in the periphery and centrally, including hypothalamic integration of energy homeostasis. Recessive mutations of ob gene result in early onset of hyperphagia, morbid obesity, metabolic disorders, early mortality and shortened life-span. Intracerebroventricular injection of recombinant adeno-associated virus vector (rAAV) encoding the leptin gene in adult obese ob/ob mice enhanced leptin transgene expression only in the hypothalamus, normalized food intake, body weight and more than doubled the life-span as compared to control cohorts and extended it to near that of normal wild type mice. These life-extending benefits were associated with drastic reductions in visceral fat, and blood glucose and insulin levels, but elevated ghrelin levels, the anti-aging biomarkers. Thus, bioavailability of leptin transduced by ectopic gene in the hypothalamus alone is both necessary and sufficient to normalize life-span. Evidently, site-specific ectopic gene expression with rAAV is durable and safe for alleviating neural disorders that stem from missing or functional disruption of a single gene.

A motilin agonist, erythromycin, decreases circulating growth hormone levels in normal subjects but not in diabetic subjects.

Erythromycin (EM) is a common antibiotic known to be a specific agonist of motilin receptors. We have previously reported that administration of EM improves glycemic control in type 2 diabetes patients. In the present study, we tested the effect of EM on growth hormone (GH) secretion in normal and type 2 diabetic subjects. Erythromycin (300 mg) was administered orally in fasted type 2 diabetic (n=12) and normal (n=10) subjects. Blood samples were obtained before and 2 h after the administration. Blood glucose, plasma insulin, somatostatin (SS), and GH levels were determined. The same fasted groups received intravenous erythromycin infusion (10 mg/kg per hour) for 60 min. Blood samples were collected just prior to the infusion and at 15, 30, 45 and 60 min, and plasma GH and somatostatin levels during the infusion were determined. Oral EM administration increased insulin levels and decreased blood glucose levels. GH levels were significantly decreased, while SS levels did not change in normal subjects. In diabetic subjects, there was an increase in insulin levels, but no change in blood glucose, SS, and GH levels. Intravenous EM infusion resulted in a marked decrease in GH levels, while no change in SS levels occurred in normal subjects. There were no changes in SS and GH levels in diabetic subjects during the infusion. When diabetic subjects were divided into two groups with and without autonomic neuropathy, no changes in GH levels were seen in either group. We conclude that EM decreases GH levels in normal subjects while not changing SS levels. This effect was not observed in type 2 diabetic subjects.

Leptin transgene expression in the hypothalamus enforces euglycemia in diabetic, insulin-deficient nonobese Akita mice and leptin-deficient obese ob/ob mice.

We have tested the hypothesis that sustained leptin action in the hypothalamus alone can engender and maintain euglycemia in wild type mice and in two monogenic diabetic models, the insulin-deficient nonobese Akita mice and the hyperinsulinemic leptin-deficient obese, ob/ob mice. A single intracerebroventricular injection of recombinant adeno-associated virus vector encoding leptin (rAAV-lep) enhanced leptin transgene expression in the hypothalamus without any evidence of leptin leakage to the peripheral circulation, and promptly reinstated euglycemia that persisted along with severe insulinopenia in all three genotypes through the 7-week period of observation. A comparative evaluation of known etiologic factors of hyperglycemia showed that this long-term benefit on glucose homeostasis was not due to diminished energy consumption, weight and adiposity, but was conferred by at least two mechanisms operating simultaneously, enhanced glucose metabolism to meet the demand for the rAAV-lep induced increased non-shivering thermogenesis mediated by brown adipose tissue and insulin hypersensitivity. These findings endorse the hypothesis that increased leptin action locally in the hypothalamus can impose euglycemia independent of pancreatic insulin, and central leptin reinforcement may serve as a newer adjunct therapy to treat type 1 and type 2 diabetes.

Mosapride improves food intake, while not worsening glycemic control and obesity, in ob/ob obese mice with decreased gastric emptying.

Many patients with diabetes mellitus complain of early satiety and postprandial gastric fullness and discomfort. Mosapride citrate, a 5-HT4 receptor agonist, enhances gastric emptying and alleviates gastrointestinal discomfort in patients with diabetic gastroparesis. This study was undertaken to investigate the effects of mosapride citrate on feeding behavior in ob/ob obese mice with decreased gastric emptying. Mosapride citrate (1 mg/kg/day) was orally administered for 7 days. Food and water intake and body weight were measured daily. Blood glucose, serum insulin, and fructosamine concentrations were measured after 7 days of treatment. Orally administered mosapride citrate significantly increased food intake in ob/ob obese mice, with a tendency to decrease fasting blood glucose and fructosamine concentrations compared with controls. There were no significant changes in body weight after 7 days of treatment with oral mosapride citrate. These observations suggest that mosapride citrate may be useful in the treatment of appetite loss and improve the quality of life in patients with diabetes mellitus.

Des-acyl ghrelin acts by CRF type 2 receptors to disrupt fasted stomach motility in conscious rats.

BACKGROUND & AIMS: Although it has been shown that des-acyl ghrelin decreases food intake and gastric emptying, no previous studies have examined the effects of des-acyl ghrelin on physiologic fed and fasted motor activity in the gastrointestinal tract. METHODS: We examined the effects of intraperitoneal (IP) administration of des-acyl ghrelin on food intake and the effects of intracerebroventricular (ICV) or intravenous (IV) administration of des-acyl ghrelin on gastroduodenal motility using freely moving conscious rat models. The brain nuclei responding to these effects were examined by c- fos immunohistochemistry of the brain sections. RESULTS: IP injection of des-acyl ghrelin decreased food intake, and this effect was not altered by capsaicin treatment. IP injection of des-acyl ghrelin enhanced c- fos expression in the arcuate and paraventricular nucleus but not in the nucleus of the solitary tract. Both ICV and IV injection of des-acyl ghrelin disrupted fasted motor activity in the antrum but not in the duodenum. Changes in gastric motility induced by IV injection of des-acyl ghrelin were completely antagonized by ICV injection of a selective corticotropin-releasing factor (CRF) 2 receptor antagonist; however, the CRF 1 receptor antagonist had no effects. CONCLUSIONS: The results suggest that des-acyl ghrelin decreases food intake and disrupts the fasted motor activity of the antrum in freely moving conscious rats. Peripheral des-acyl ghrelin may induce this function by direct activation of brain receptor by crossing the blood-brain barrier but not by the activation of vagal afferent pathways. In the brain, CRF 2 receptor, but not CRF 1 receptor, is involved in this action.

Helicobacter pylori infection is associated with colon adenomatous polyps detected by high-resolution colonoscopy.

Helicobacter pylori (H. pylori) is associated with the development of cancer in the stomach, but both positive and negative associations were reported with colorectal neoplasia. We sought to determine whether H. pylori is associated with colon neoplasia in Japanese population. We examined 332 patients who underwent routine high-resolution total colonoscopy and serologic testing for IgG antibodies agonist H. pylori. Subjects who received cyclooxygenase-2 inhibitors or previous eradication therapy and those with borderline titer levels were excluded from data analysis (n = 27). Seronegative control subjects were from the same study population to maximize the representativeness. There were no significant differences in age and gender between the 2 patient groups. A significant increase in the incidence of adenomatous polyps (p < 0.0001) and decrease in normal colonoscopic findings (p < 0.0005) were observed in seropositive patients than those seronegative. Our study indicates an etiological link of H. pylori infection to colorectal neoplasia and the need of routine colonoscopy in seropositive patients.

Melanin-concentrating hormone enhances sucrose intake.

Melanin-concentrating hormone (MCH) is known to be an important regulator for feeding and energy balance. MCH was recently reported to stimulate water intake independent of food intake. The purpose of the present study is to examine the dipsogenic response of MCH with special emphasis on sweetened beverages, the preference for which is well documented in diabetic animals. Our results showed that intracerebroventricular injection of MCH acutely increased food as well as water intake. Human (h)MCH and salmon (s)MCH increased water intake independent of food intake, which was not suppressed by angiotensin antagonists. hMCH and sMCH significantly increased both sucrose solution and food intake; on the other hand, agouti-related protein (AgRP) stimulated food but not sucrose intake when provided simultaneously. MCH-treated rats significantly increased the ingestion of sucrose and glucose solution, but not of saccharin, indicating that MCH-induced dipsogenic response is more related to caloric content than sweet taste per se. Significant correlation was observed between the sucrose intake and the mRNA expression of MCH and MCHR1 in normal rats. These results indicate that MCH may be an important regulator of sugar intake in normal as well as in obese diabetic animals.

Stimulation of appetite by ghrelin is regulated by leptin restraint: peripheral and central sites of action.

A reciprocal rhythmic pattern of 2 afferent hormonal signals, anorexigenic leptin and orexigenic ghrelin, imparts rhythmicity to the neuropeptide Y (NPY) system, the final common pathway for appetite expression in the hypothalamus. We now show that leptin inhibits both the secretion of gastric ghrelin and the stimulation of feeding by ghrelin. We propose that this dual leptin restraint is the major regulatory arm of the feedback communication between the periphery and the hypothalamus for weight homeostasis, and disruption in the rhythmic communication at any locus in the leptin-ghrelin-NPY feedback loop impels loss of hypothalamic control, leading to abnormal weight gain and obesity.

Development of pancreatic islets in pancreatic polypeptide-overexpressing mice.

Recently we produced pancreatic polypeptide transgenic (PPTG) mice and found that PP was overexpressed in pancreatic islets. The present study examines development of four islet hormones in PPTG mice at embryonic days (ED) 15, 17, and 19, and in adult animals. Adult PPTG mice showed massive aggregation of PP-positive cells and glucagon-positive cells seen at the central area of the islets. Confocal laser microscopic study showed that three islet hormones (insulin, glucagon and PP) were completely overlapped in islets of PPTG mice. Overlapping of somatostatin/glucagon and somatostatin/PP were also increased at the peripheral area of the islets in adult PPTG mice compared to wild-type mice. In prenatal development of pancreatic islets of PPTG mice, somatostatin/glucagon overlapping cells appeared at ED 15, two days earlier than in wild-type mice. Differentiation of these somatostatin/glucagon double-positive cells into single-positive cells was disturbed in the PPTG mice during perinatal to postnatal periods. Differentiation of glucagon/insulin-double positive cells into single-positive cells was disturbed remarkably in postnatal development of the islets of PPTG mice. The present results suggest that early and overexpression of PP may engender the early appearance of somatostatin producing cells; however, that may disturb differentiation of multihormonal immature endocrine cells into single hormonal mature endocrine cells.