Lack of GPR40/FFAR1 does not induce diabetes even under insulin resistance condition.

AIMS: G protein-coupled receptor/free fatty acid receptor 1 (GPR40/FFAR1 ) regulates free fatty acid-induced insulin secretion. This study has been performed to clarify whether or not loss of GPR40/FFAR1 function exacerbates diabetes, that is, whether GPR40 has an essential physiological role in the development of diabetes or not. METHODS: We generated GPR40/FFAR1 knockout (KO) mice and analysed their phenotypes in vitro and in vivo under the condition of dietary or genetically induced insulin resistance. RESULTS: GPR40/FFAR1 KO mice kept on a high-fat diet became obese, developed glucose intolerance to a similar degree as GPR40/FFAR1 wild-type (WT) mice. In addition, the phenotype of KO mice harbouring diabetogenic KK background genes showed glucose intolerance at a level similar to level for control KK mice. In both mouse models with insulin resistance, insulin secretion after oral glucose load and homeostasis model assessment-insulin resistance (HOMA-IR) did not change between GPR40/FFAR1 KO and WT mice. Although glucose-induced insulin secretion under high palmitate concentration was significantly lower in KO than in WT islets, pancreatic insulin content and insulin secretion stimulated with glucose alone were not different between KO and WT mice. CONCLUSIONS: GPR40/FFAR1 has a major role in regulating fatty-acid-mediated insulin secretion, but the lack of GPR40/FFAR1 does not exacerbate glucose intolerance and insulin resistance induced by high-fat diet or diabetogenic KK gene. Our findings indicate that loss of GPR40/FFAR1 function does not play an important role in inducing or exacerbating diabetes.

Alterations in basal and glucose-stimulated voltage-dependent Ca2+ channel activities in pancreatic beta cells of non-insulin-dependent diabetes mellitus GK rats.

In genetically occurring non-insulin-dependent diabetes mellitus (NIDDM) model rats (GK rats), the activities of L- and T-type Ca2+ channels in pancreatic beta cells are found to be augmented, by measuring the Ba2+ currents via these channels using whole-cell patch-clamp technique, while the patterns of the current-voltage curves are indistinguishable. The hyper-responsiveness of insulin secretion to nonglucose depolarizing stimuli observed in NIDDM beta cells could be the result, therefore, of increased voltage-dependent Ca2+ channel activity. Perforated patch-clamp recordings reveal that the augmentation of L-type Ca2+ channel activity by glucose is markedly less pronounced in GK beta cells than in control beta cells, while glucose-induced augmentation of T-type Ca2+ channel activity is observed neither in the control nor in the GK beta cells. This lack of glucose-induced augmentation of L-type Ca2+ channel activity in GK beta cells might be causatively related to the selective impairment of glucose-induced insulin secretion in NIDDM beta cells, in conjunction with an insufficient plasma membrane depolarization due to impaired closure of the ATP-sensitive K+ channels caused by the disturbed intracellular glucose metabolism in NIDDM beta cells.

VLDL triglyceride kinetics in Wistar fatty rats, an animal model of NIDDM: effects of dietary fructose alone or in combination with pioglitazone.

The effects of dietary fructose alone or in combination with a new oral agent, pioglitazone, on VLDL-triglyceride (TG) turnover were studied in genetically obese Wistar fatty rats characterized by hyperinsulinemia (7,488 +/- 954 pmol/l), hyperglycemia, (22.5 +/- 1.4 mmol/l), and hypertriglyceridemia (4.39 +/- 0.54 mmol/l). They had an increased hepatic TG production (16.2 +/- 0.1 micromol/min; lean rats, 5.4 +/- 0.3 micromol/min) as well as a longer half-life of VLDL-TG from lean donors (8.8 +/- 1.4 min, lean recipients; 2.3 +/- 0.9 min). In addition, in lean recipients, the half-life of VLDL-TG from fatty donors was longer than that from lean donors (4.80 +/- 0.56 vs. 3.14 +/- 0.23 min). Although feeding fructose into fatty rats did not change plasma glucose and insulin levels, it produced a twofold increase in TG levels (8.74 +/- 1.15 mmol/l). This was associated with a 1.7-fold increase in TG production to 27.5 +/- 1.2 micromol/min, while no significant change was found in the half-life of lean VLDL-TG in fructose-fed fatty recipients (10.9 +/- 2.4 min) or in that of VLDL-TG from fructose-fed fatty donors in lean recipients (4.46 +/- 0.76 min). Daily administration of pioglitazone (3 mg/kg body weight) in fructose-fed fatty rats ameliorated glycemia and triglyceridemia to the level of lean rats (8.1 +/- 0.7 and 1.18 +/- 0.05 mmol/l, respectively) and insulinemia to a lesser extent (2,712 +/- 78 pmol/l). A fall in TG levels was associated with improvement of an impairment in the ability of fructose-fed fatty rats to remove lean VLDL-TG (half-fife: 2.6 +/- 0.6 min). Pioglitazone, however, produced no change in TG production (25.9 +/- 2.7 micromol/min), the half-life of VLDL-TG from fructose-fed fatty donors in lean recipients (4.17 +/- 0.38 min), or the activity of lipoprotein lipase and hepatic lipase in postheparin plasma. We conclude that in Wistar fatty rats 1) hypertriglyceridemia is attributed to TG overproduction and impaired TG catabolism, and the latter is due to changes in both VLDL, such that they are less able to be removed, and changes in the nature of Wistar fatty rats, such that they are less able to remove VLDL-TG; 2) fructose further increases hepatic TG production with a resultant deterioration in hypertriglyceridemia; 3) pioglitazone normalizes TG levels by altering the physiology of the Wistar fatty rats in a manner that increases their ability to remove VLDL-TG from the circulation.

Hyperglycemia causes oxidative stress in pancreatic beta-cells of GK rats, a model of type 2 diabetes.

Reactive oxygen species are involved in a diversity of biological phenomena such as inflammation, carcinogenesis, aging, and atherosclerosis. We and other investigators have shown that the level of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a marker for oxidative stress, is increased in either the urine or the mononuclear cells of the blood of type 2 diabetic patients. However, the association between type 2 diabetes and oxidative stress in the pancreatic beta-cells has not been previously described. We measured the levels of 8-OHdG and 4-hydroxy-2-nonenal (HNE)-modified proteins in the pancreatic beta-cells of GK rats, a model of nonobese type 2 diabetes. Quantitative immunohistochemical analyses with specific antibodies revealed higher levels of 8-OHdG and HNE-modified proteins in the pancreatic beta-cells of GK rats than in the control Wistar rats, with the levels increasing proportionally with age and fibrosis of the pancreatic islets. We further investigated whether the levels of 8-OHdG and HNE-modified proteins would be modified in the pancreatic beta-cells of GK rats fed with 30% sucrose solution or 50 ppm of voglibose (alpha-glucosidase inhibitor). In the GK rats, the levels of 8-OHdG and HNE-modified proteins, as well as islet fibrosis, were increased by sucrose treatment but reduced by voglibose treatment. These results indicate that the pancreatic beta-cells of GK rats are oxidatively stressed, and that chronic hyperglycemia might be responsible for the oxidative stress observed in the pancreatic beta-cells.

Increased adipose expression of the uncoupling protein-3 gene by thiazolidinediones in Wistar fatty rats and in cultured adipocytes.

Uncoupling protein (UCP) 3 and UCP2, mitochondrial carrier proteins dissipating electrochemical gradient across the mitochondrial inner membrane, have been implicated in the regulation of energy metabolism. The UCP3 gene is expressed abundantly in the skeletal muscle, while the UCP2 gene is detected in the white adipose tissue (WAT) with diffuse localization throughout the body. Uncoupling of electron transport and ATP synthesis has been reported to increase glucose uptake, suggesting that UCP may be involved in glucose metabolism. Thiazolidinediones (TZDs), which are insulin-sensitizing agents for NIDDM, have been reported to increase energy expenditure. To elucidate the pathophysiologic significance of UCP3 and UCP2 in the effect of TZDs on glucose metabolism and energy expenditure, we examined their basal mRNA levels in the WAT, brown adipose tissue (BAT), and skeletal muscle from Wistar fatty rats, a rat model of NIDDM and obesity with leptin receptor defect, and investigated expression of the genes encoding UCP3 and UCP2 in Wistar fatty rats and in Wistar lean rats with 2-week oral administration of 3 mg x kg(-1) x day(-1) pioglitazone, a TZD derivative. Basal UCP3 mRNA levels were significantly lower (38 +/- 8, 45 +/- 13, and 76 +/- 6%) in the retroperitoneal WAT, BAT, and skeletal muscle from Wistar fatty rats than in those from Wistar lean rats, while basal UCP2 mRNA levels were significantly higher by 2.1-, 1.8-, and 2.5-fold in the subcutaneous WAT, retroperitoneal WAT, and BAT from Wistar fatty rats, respectively, than in those from Wistar lean rats. In pioglitazone-treated Wistar fatty rats, UCP3 mRNA levels were significantly increased by 2.1-, 2.0-, and 1.6-fold in the epididymal WAT, retroperitoneal WAT, and BAT, respectively, as compared with those in nontreated fatty rats. In pioglitazone-treated lean rats, UCP3 mRNA levels were significantly increased by 1.3-fold in the BAT as compared with those in nontreated lean rats. No significant change of UCP2 mRNA levels was observed in pioglitazone-treated fatty and lean rats. In addition, to examine the direct effect of TZDs on adipocytes, we examined the regulation of UCP3 and UCP2 gene expression using the primary culture of rat mature adipocytes from Sprague-Dawley rats. In rat cultured mature adipocytes, UCP3 mRNA levels were increased in a dose-responsive manner by 10(-5) to 10(-4) mol/l pioglitazone, while there was no significant change of UCP2 mRNA levels. These results clearly demonstrate that UCP3 gene expression is upregulated by TZDs in the WAT and BAT in Wistar fatty rats, an obese model with leptin receptor defect, and that adipose UCP3 gene expression is increased in response to TZDs in vitro. The present study suggests the involvement of UCP3 in the effects of TZDs on energy and glucose metabolism.

Increased glucose metabolism and insulin sensitivity in transgenic skinny mice overexpressing leptin.

Excess of body fat, or obesity, is a major health problem and confers a higher risk of cardiovascular and metabolic disorders such as diabetes, hypertension, and coronary heart disease. Leptin is an adipocyte-derived satiety factor that plays an important role in the regulation of energy homeostasis, and its synthesis and secretion are markedly increased in obese subjects. To explore the metabolic consequences of an increased amount of leptin on a long-term basis in vivo, we generated transgenic skinny mice with elevated plasma leptin concentrations comparable to those in obese subjects. Overexpression of leptin in the liver has resulted in complete disappearance of white and brown adipose tissue for a long period of time in mice. Transgenic skinny mice exhibit increased glucose metabolism accompanied by the activation of insulin signaling in the skeletal muscle and liver. They also show small-sized livers with a marked decrease in glycogen and lipid storage. The phenotypes are in striking contrast to those of recently reported animal models of lipoatrophic diabetes and patients with lipoatrophic diabetes with reduced amount of leptin. The present study provides evidence that leptin is an adipocyte-derived antidiabetic hormone in vivo and suggests its pathophysiologic and therapeutic implications in diabetes.

Effect of an intestinal disaccharidase inhibitor (AO-128) on obesity and diabetes.

A new disaccharidase inhibitor, AO-128, showed 190-3900-fold more potent inhibition of purified rat small intestine sucrase-isomaltase (S-1) complex and 23-33-fold more potent inhibition of semipurified porcine small intestine disaccharidases than acarbose. AO-128 suppressed elevation of the blood glucose concentration after oral sucrose, maltose, and starch, but not after oral glucose, fructose, and lactose. The chronic addition of AO-128 to the diet produced antiobesity and antidiabetic actions in obese and/or diabetic animals. Undesirable side effects, such as diarrhea and soft feces, were observed only for the first 5-7 d and suppression of intestinal disaccharidase activities was observed even at the end of the experiment, suggesting that the suppressive or delaying effect of AO-128 on elevation of the postprandial blood glucose concentrations is involved in reduction in body weight gain and prevention and/or amelioration of the diabetic state. Thus, AO-128 is useful as an adjunct to the dietary management of obesity and diabetes.

TMP-153, a novel ACAT inhibitor, lowers plasma cholesterol through its hepatic action in golden hamsters.

The mechanism of the hypocholesterolemic action of N-[4-(2-chlorophenyl)-6,7-dimethyl-3-quinolyl]-N'-(2, 4-difluorophenyl) urea (TMP-153), a potent acyl-CoA:cholesterol acyltransferase (ACAT) inhibitor, was studies in Golden hamsters. TMP-153 (0.5-1.5 mg/kg) dose-dependently reduced plasma total- and low density lipoprotein (LDL)-cholesterol without affecting high density lipoprotein (HDL)-cholesterol. TMP-153 markedly reduced the cholesterol influx into the plasma upon intravenous injection of Triton WR-1339. The compound also decreased cholesterol absorption calculated from dietary intake, biliary secretion and the absorption co-efficient. Hepatic cholesterol secretion was calculated by substracting the cholesterol absorption from the cholesterol influx. In hamsters, the liver accounted for 92% of the cholesterol influx with the remaining 8% coming from the intestine, and both were markedly decreased by TMP-153. Thus, it is likely that TMP-153 lowers plasma cholesterol through its hepatic action. In the liver, the compound significantly reduced the unesterified cholesterol content in addition to markedly reducing the content of esterified cholesterol. In accordance with this reduction, the half-life time of [125I]-LDL was significantly shortened by the compound, suggesting an increase in LDL receptors. However, the hepatic cholesterogenesis from [14C]acetate was decreased by TMP-153 treatment. This effect seems to be secondary, since the compound did not inhibit cholesterogenesis from [14C]acetate in HepG2 cells. From the data described above, the contribution of hepatic secretion and intestinal absorption of cholesterol to the plasma cholesterol level in Golden hamsters are discussed.

TMP-153, a novel ACAT inhibitor, inhibits cholesterol absorption and lowers plasma cholesterol in rats and hamsters.

Effects of TMP-153, N-[4-(2-chlorophenyl)-6,7-dimethyl-3-quinolyl]-N'-(2,4-difluorophe nyl)urea, on intestinal and hepatic acyl-CoA:cholesterol acyltransferase (ACAT) activities, cholesterol absorption and plasma cholesterol level in rats and hamsters were studied. TMP-153 has IC50 values of around 5-10 nM for the hepatic and intestinal ACAT from various animals. The most potent inhibition was observed in the intestinal ACAT from Golden hamsters (IC50 = 2.3 nM). The inhibition mode of TMP-153 was non-competitive for rat intestinal ACAT. TMP-153 inhibited cholesterol esterification both in human colonic adenocarcinoma cells, LS180, and in human hepatoma cells, HepG2 (IC50 = 150 nM and 330 nM, respectively). [14C]cholesterol and cold cholesterol absorption from the small intestine was markedly inhibited by oral administration of TMP-153 (1 mg/kg) without affecting lymph flow and triglyceride absorption. When the compound was given as a dietary admixture, plasma cholesterol was reduced in rats fed a cholesterol diet (ED50 = 0.25 mg/kg/day), but not in those fed a stock diet. On the other hand, TMP-153 showed more prominent hypocholesterolemic effect in Golden hamsters fed the stock diet (ED50 = 0.81 mg/kg/day) than in those fed the cholesterol diet (ED50 = 8.01 mg/kg/day). In hamsters fed the stock diet, TMP-153 markedly decreased the hepatic unesterified cholesterol in addition to esterified cholesterol content, but did not affect bile flow and the biliary secretion of bile acid and lipids. Different mechanisms for plasma cholesterol lowering by TMP-153 between rats and hamsters was discussed.

Inhibition of progressive reduction of islet beta-cell mass in spontaneously diabetic Goto-Kakizaki rats by alpha-glucosidase inhibitor.

The Goto-Kakizaki (GK) rat, an animal model of type 2 diabetes, exhibits mild hyperglycemia with a reduction of beta-cell mass. The mechanism for islet structural changes in this model and whether the changes are affected by metabolic control are not known. In the present study, we examined the process of islet changes in male GK rats aged 6, 8, 12, 24, and 36 weeks. Treatment effects with an alpha-glucosidase inhibitor (Voglibose; Takeda, Osaka, Japan) for 24 weeks (12 to 36 weeks of age) were also evaluated. The beta-cell mass increased until 8 weeks of age in both GK and control rats, but the increase was significantly (P < .01) smaller in GK rats versus at 8 weeks of age. Thereafter, the beta-cell mass decreased in GK rats, whereas it remained constant in controls. Voglibose treatment significantly (P < .01) inhibited the reduction of beta-cell mass in GK rats. Proliferative activity of beta cells as measured by bromodeoxyuridine (BrdU) uptake was significantly (P < .05) lower in GK rats versus control rats at 6 and 8 weeks, but the difference disappeared after 12 weeks of age, regardless of Voglibose treatment. The present study thus demonstrates a progressive loss of beta cells in GK rats that was mitigated by Voglibose treatment. We consider that the beta-cell loss in GK rats was due to an early impairment in proliferative activity and reduced survival. Voglibose did not appear to stimulate beta-cell proliferation, but exerted its effect via a reduction of hyperglycemia.

Marked reduction of pancreatic insulin content in male ventromedial hypothalamic-lesioned spontaneously non-insulin-dependent diabetic (Goto-Kakizaki) rats.

The effects of ventromedial hypothalamic (VMH) lesions were examined in male and female non-obese non-insulin-dependent diabetic (Goto-Kakizaki [GK]) rats with respect to glucose metabolism and pancreatic insulin content. VMH lesions produced hyperphagia and hyperinsulinemia in both male and female GK rats. In male rats, plasma glucose levels of VMH-lesioned GK rats (22.7 +/- 3.1 mmol/L) were significantly greater than the levels of sham-operated GK rats (10.6 +/- 1.0 mmol/L, P < .001) at 7 weeks after the operation, although there were no differences in these levels between VMH-lesioned and sham-operated groups in Wistar rats. Plasma insulin levels in male VMH-lesioned GK rats tended to be lower at 7 weeks than at 1 week. VMH lesions caused a significant decrease in the pancreatic insulin content of male GK rats (12.0 +/- 2.3 nmol/L/g pancreas) compared with male sham-operated rats (15.8 +/- 1.4 nmol/L/g pancreas, P < .05) 9 weeks postoperatively. In contrast to the results in male rats, female GK rats showed no differences in plasma glucose levels between VMH-lesioned and sham-operated groups at 7 weeks. Female VMH-lesioned GK rats also showed no difference in plasma insulin levels between 1 week and 7 weeks. The pancreatic insulin level of female VMH-lesioned GK rats was unchanged from that of female sham-operated GK rats. The insulin content was significantly greater in the VMH-lesioned Wistar group than in the sham-operated Wistar group, regardless of sex.(ABSTRACT TRUNCATED AT 250 WORDS)

PVN-lesioned obese rats maintain ambulatory activity and its circadian rhythm.

We investigated physical activity and its circadian rhythm as well as food and water intake in PVN-lesioned rats compared to those of VMH-lesioned rats. Body weight, food and water intake and ambulatory activity were recorded automatically on a microcomputer on the fourth day after creation of the PVN or VMH lesion. The weight gain in the PVN-lesioned rats was almost the same as that of the VMH-lesioned rats. The PVN-lesioned rats maintained the same circadian rhythm of eating and drinking as the controls. The ambulatory activity in the VMH-lesioned rats during the 24-h period was significantly less than the sham-operated rats, but that of the PVN-lesioned rats was almost the same as the sham-operated rats. The dominance of ambulatory activity in the dark period was observed in the PVN-lesioned rats as well as controls, in contrast to the VMH-lesioned rats, in which circadian rhythm was abolished. These results demonstrate that the PVN-lesioned obese rats show clear differences in physiological behavior from the VMH-lesioned rats.

An alpha-glucosidase inhibitor, AO-128, retards carbohydrate absorption in rats and humans.

The present study was designed to determine the possible significance of a therapeutic dose (0.2 mg) of AO-128 on carbohydrate absorption by measuring the breath hydrogen concentration, which is an index of the amount of unabsorbed carbohydrate in the large intestine. Post-prandial hyperglycemia is common among diabetic patients. AO-128, a potent alpha-glucosidase inhibitor, suppressed post-prandial hyperglycemia and hyperinsulinemia in healthy volunteers at a dose of 0.2 mg with each meal. These volunteers increased the breath hydrogen concentration in response to ingestion of non-absorbable lactulose, but decreased only slightly its concentration from the basal level after sucrose ingestion, indicating complete absorption. When AO-128 (0.2 mg) was given with sucrose, hydrogen production increased only slightly compared with placebo, suggesting that the inhibitory effect of AO-128 on sucrose absorption was minimal. Only 5 g of the 100 g of sucrose was not absorbed and this 5% reduction is too small to explain the observed inhibitory effect on the post-prandial rise in plasma glucose. Sucrose loading in rats (about 443 mg) sharply increased blood glucose and was accompanied by the rapid disappearance of sucrose from the upper small intestine. AO-128 (0.03 or 0.1 mg/kg) lessened the elevation of blood glucose after sucrose ingestion. The lower dose (0.03 mg/kg) retarded small intestinal absorption, but did not induce an influx of sucrose into the cecum and large intestine, while the higher dose (0.1 mg/kg) caused an increased influx of sucrose into the large bowel. These results indicated that AO-128 retards the absorption of carbohydrate and reduces post-prandial hyperglycemia.

Long-term therapeutic effects of voglibose, a potent intestinal alpha-glucosidase inhibitor, in spontaneous diabetic GK rats.

The effect of long-term (6 months) administration of voglibose in a dietary mixture (10 ppm) on intestinal disaccharidase activity was examined in non obese type 2 diabetes model Goto-Kakizaki (GK) rats. The postprandial blood glucose level in voglibose-treated GK rats was significantly lower than in untreated GK rats (190+/-19 vs. 250+/-25 mg/dl, P<0.01; 1 h, 212+/-23 vs. 256+/-20, P<0.05; 2 h), and the activities of maltase, sucrase, and isomaltase remained significantly lower throughout the 6 months of voglibose treatment. The expressions of protein and mRNA of sucrase-isomaltase (SI) complex were significantly higher in voglibose-treated GK rats. Voglibose administration then was stopped after 6 months of treatment. The mRNA level and protein level of the SI complex became normalized during the interruption of drug administration, and disaccharidase activities increased almost to the level of the untreated group 1 month after treatment was stopped. After 1 day of re-administration of the drug, however, disaccharidase activities again became significantly inhibited. These results indicate that voglibose may improve glucose tolerance since it inhibits activities of disaccharidases in spite of increasing the expression of them on intestine, furthermore voglibose may be reversible and reproducible through interruption and re-administration.

Suppressive effect of ipriflavone on bone depletion in the experimental diabetic rat: dose response of ipriflavone.

The dose dependent effect of ipriflavone (7-isopropoxy-isoflavone) on the femoral bone in streptozotocin-induced diabetic rats was studied by microdensitometric analysis. Diabetic rats showed severe hyperglycemia, glucosuria, hypoinsulinemia, associated with increased urinary calcium and hydroxyproline. Microdensitometric analysis revealed decreases in femoral length, bone width, and bone density. The dietary administration of ipriflavone (about 270 mg/kg/day) to the diabetic rats for 6 weeks prevented reduction of the cortical thickness index in the diaphysis and depletion of bone density in the distal metaphysis, and also reduced the inner diameter of the diaphysis; diabetic state was not improved. A simple correlation and linear regression analysis revealed that ipriflavone also significantly reduced the inner diameter in the diaphysis at a dose of 90 mg/kg/day, but not at one of 25 mg/kg/day. These results suggest that ipriflavone suppresses the depletion of the femoral bone through inhibition of bone resorption in a dose dependent fashion; its minimum effective dose is 90 mg/kg/day in experimental diabetes.

Antiobesity and antidiabetic actions of a new potent disaccharidase inhibitor in genetically obese-diabetic mice, KKA(y).

AO-128 is a potent and structurally novel inhibitor of the intestinal disaccharidases, such as maltase and sucrase. Genetically obese-diabetic mice, KKA(y), were used to examine the acute or long-term effectiveness of this compound. AO-128 decreased a postprandial rise in blood glucose after sucrose solution loading dose-dependently; the ED50 to reduce a delta increment of blood glucose by 50% was 0.22 mg/kg. The intestinal sucrase and maltase activities were suppressed to 7 and 48% of the control levels, respectively, at a dose of 0.21 mg/kg. Four-week-old female KKA(y) mice were kept on a laboratory diet containing 10 or 50 ppm of AO-128 for 12 weeks. The high dose of AO-128 reduced food intake and body weight gain throughout the experimental period. On the other hand, the low dose reduced body weight gain for the first 4 weeks without any effect on food intake. Development of the hyperglycemia and hyperinsulinemia characteristic of KKA(y) mice was moderately prevented by the low dose, and completely by the high dose. Hypertriglyceridemia tended to be suppressed by the AO-128 treatment. The high dose decreased the hemoglobin A1 level and parametrial adipose tissue weight. Hepatomegaly and fatty liver were ameliorated by AO-128 dose-dependently. Nephropathy was ameliorated by the high dose. These findings indicate that AO-128 may be useful for treating human obesity and diabetes.

Allylthiamindisulfide and related compounds enhance thermogenesis with increasing noradrenaline and adrenaline secretion in rats.

The effects of allylthiamindisulfide, an allyl derivative of thiamin, and related compounds on thermogenesis were investigated by measuring noradrenaline and adrenaline secretion and the temperatures of interscapular brown adipose tissue (IBAT) and rectum in rats. In Experiment 1, the effects of the administrations of allylthiamindisulfide and related compounds on noradrenaline and adrenaline secretion were evaluated as compared to thiamin in anesthetized rats. The administration of allylthiamindisulfide significantly increased the plasma concentrations of noradrenaline and adrenaline. These increases were dose dependent, while that of thiamin was not. Four synthetic compounds related to allylthiamindisulfide also increased the plasma adrenaline and noradrenaline concentrations. In Experiment 2, the effects of allylthiamindisulfide on thermogenesis were investigated by the direct measurement of temperatures in the IBAT and rectum in anesthetized rats, and compared to the effects induced by thiamin and diallyldisulfide. The temperatures in the IBAT and rectum were significantly increased by the administration of allylthiamindisulfide and diallyldisulfide, while there was no significant increase as the result of thiamin administration. These results suggest that allylthiamindisulfide and related compounds enhance thermogenesis by increasing noradrenaline and adrenaline secretion in rats.

[Two cases of idiopathic ventricular fibrillation with interesting electrocardiographic findings].

We encountered two cases of ventricular fibrillation (VF) without overt heart disease. The first case we report is that of a 47-year-old man, and the second case is a 39-year-old man. VF occurred in the night unrelated to myocardial ischemia or myocarditis. Their basic ECGs showed normal sinus rhythm, but neither QT prolongation nor abnormal Q wave was seen. But we could see IRBBB and ST segment elevation in the V1-2 lead not only in the acute phase, but also in the chronic phase. Abnormal findings were not found in noninvasive cardiac examinations, nor in cardiac catheterization and histological examinations. In the second case, VF was induced by electrical stimulation, and Disopyramide was found to be effective for the prevention of VF. The patient in the first case died suddenly two years after his first attack. Both cases have interesting ECG findings, and it may be that they play on important role in discovering the etiology of sudden cardiac death.

Combining a dipeptidyl peptidase-4 inhibitor, alogliptin, with pioglitazone improves glycaemic control, lipid profiles and beta-cell function in db/db mice.

BACKGROUND AND PURPOSE: Alogliptin, a highly selective dipeptidyl peptidase-4 (DPP-4) inhibitor, enhances incretin action and pioglitazone enhances hepatic and peripheral insulin actions. Here, we have evaluated the effects of combining these agents in diabetic mice. EXPERIMENTAL APPROACH: Effects of short-term treatment with alogliptin alone (0.01%-0.1% in diet), and chronic combination treatment with alogliptin (0.03% in diet) and pioglitazone (0.0075% in diet) were evaluated in db/db mice exhibiting early stages of diabetes. KEY RESULTS: Alogliptin inhibited plasma DPP-4 activity up to 84% and increased plasma active glucagon-like peptide-1 by 4.4- to 4.9-fold. Unexpectedly, alogliptin alone lacked clear efficacy for improving glucose levels. However, alogliptin in combination with pioglitazone clearly enhanced the effects of pioglitazone alone. After 3-4 weeks of treatment, combination treatment increased plasma insulin by 3.8-fold, decreased plasma glucagon by 41%, both of which were greater than each drug alone, and increased plasma adiponectin by 2.4-fold. In addition, combination treatment decreased glycosylated haemoglobin by 2.2%, plasma glucose by 52%, plasma triglycerides by 77% and non-esterified fatty acids by 48%, all of which were greater than each drug alone. Combination treatment also increased expression of insulin and pancreatic and duodenal homeobox 1 (PDX1), maintained normal beta-cell/alpha-cell distribution in islets and restored pancreatic insulin content to levels comparable to non-diabetic mice. CONCLUSIONS AND IMPLICATIONS: These results indicate that combination treatment with alogliptin and pioglitazone at an early stage of diabetes improved metabolic profiles and indices that measure beta-cell function, and maintained islet structure in db/db mice, compared with either alogliptin or pioglitazone monotherapy.