JTT-654, an 11-beta hydroxysteroid dehydrogenase type 1 inhibitor, improves hypertension and diabetic kidney injury by suppressing angiotensinogen production.

11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1) plays an important role in regulating the expression of glucocorticoid actions in target tissues. Overexpression of 11ß-HSD1 in mouse adipose tissue causes a metabolic syndrome-like phenotype, leading to hypertension. Although, many 11ß-HSD1 inhibitors have been studied, few have shown a clear ameliorative effect against hypertension. We investigated whether JTT-654, a novel 11ß-HSD1 inhibitor, ameliorated hypertension and elucidated the underlying mechanisms. JTT-654 showed inhibitory effects on angiotensinogen production in cortisone-treated 3T3-L1 adipocytes and in a rat model. JTT-654 improved hypertension not only in cortisone-treated rats and spontaneously hypertensive rats (SHR), but also in SHR/NDmcr-cp rats. In the SHR study, JTT-654 and losartan showed the same degree of antihypertensive efficacy. In addition, JTT-654 ameliorated diabetic nephropathy by suppressing renal angiotensinogen production in SHR/NDmcr-cp rats. These effects of JTT-654 were independent of its insulin-sensitizing effects, and similar effects were not observed for pioglitazone, an insulin sensitizer. Moreover, JTT-654 did not affect normotension or hypothalamus-pituitary-adrenal (HPA) axis function in normal Sprague-Dawley rats. Our results indicate that JTT-654 ameliorates hypertension and diabetic nephropathy by inhibiting 11ß-HSD1 in the adipose tissue, liver, and kidney.

Protective Effect of Pemafibrate Treatment against Diabetic Retinopathy in Spontaneously Diabetic Torii Fatty Rats.

Diabetic retinopathy (DR) can cause visual impairment and blindness, and the increasing global prevalence of diabetes underscores the need for effective therapies to prevent and treat DR. Therefore, this study aimed to evaluate the protective effect of pemafibrate treatment against DR, using a Spontaneously Diabetic Torii (SDT) fatty rat model of obese type 2 diabetes. SDT fatty rats were fed either a diet supplemented with pemafibrate (0.3 mg/kg/d) for 16 weeks, starting at 8 weeks of age (Pf SDT fatty: study group), or normal chow (SDT fatty: controls). Normal chow was provided to Sprague-Dawley (SD) rats (SD: normal controls). Electroretinography (ERG) was performed at 8 and 24 weeks of age to evaluate the retinal neural function. After sacrifice, retinal thickness, number of retinal folds, and choroidal thickness were evaluated, and immunostaining was performed for aquaporin-4 (AQP4). No significant differences were noted in food consumption, body weight, or blood glucose level after pemafibrate administration. Triglyceride levels were reduced, and high-density lipoprotein cholesterol levels were increased. Extension of oscillatory potential (OP)1 and OP3 waves on ERG was suppressed in the Pf SDT fatty group. Retinal thickness at 1500 microns from the optic disc improved in the Pf SDT fatty group. No significant improvements were noted in choroidal thickness or number of retinal folds. Quantitative analyses showed that AQP4-positive regions in the retinas were significantly larger in the Pf SDT fatty group than in the SDT fatty group. The findings suggest that pemafibrate treatment can exert protective effects against DR.

Renal transcriptome analysis of uninephrectomized db/db mice identified a mechanism for the transition to severe diabetic nephropathy.

Diabetic nephropathy (DN), included in diabetic kidney disease (DKD), is a primary driver of end-stage renal disease (ESRD) leading to dialysis treatment. To develop new therapeutic drugs to prevent ESRD and avoid dialysis treatment, insight into DKD pathophysiology and animal models suitable for drug efficacy testing are needed. In this study, transcriptome analysis of kidneys from 26-week-old and 35-week-old uninephrectomized (UNX) db/db mice was used to identify the pathways that affect the deterioration of renal function in db/db mice. Differentially expressed genes suggested that there was increased interferon (IFN)-γ signaling during the 26 to 35-week period. Modules that changed between 26 and 35 weeks of age extracted by weighted gene co-expression network analysis (WGCNA) suggested increased the tumor necrosis factor (TNF)-α and nuclear factor-kappa B (NF-κB) signaling pathway in component cells of glomeruli. The protein-protein interaction (PPI) network analysis identified Cxcl16 as a hub gene for those signaling pathways, and it was shown that the pathways in this module changed when the glomerular filtration rate decreased in patients with DN. These results suggested the possibility that signaling mediated by Cxcl16 induced by IFN-γ and TNF-α between 26 and 35 weeks of age leads to renal fibrosis, resulting in severe disease. Drugs that target such pathways can be options for developing drugs for DN. We also think that the uninephrectomized db/db mouse can be used as an animal model of severe DKD and to evaluate efficacy in patients with DN.

Effects of salt supplementation in uninephrectomized KK-Ay mice: Examining the potential of a diabetic kidney disease model.

Diabetic kidney disease (DKD) is the leading cause of end-stage renal disease (ESRD). Although current therapeutic strategies for DKD, including sodium-glucose cotransporter-2 inhibitors and mineralocorticoid receptor antagonists, have shown some degree of efficacy, they have failed to completely halt the progression of DKD to ESRD owing to the complexity of DKD pathogenesis. Elucidating the pathophysiological mechanism of DKD is essential for the development of novel therapeutic strategies. In this study, we investigated the pathophysiological characteristics of uninephrectomized (UNx) KK-Ay mice and examined the effects of salt supplementation on the acceleration of renal injury in these mice. UNx KK-Ay mice exhibited pathophysiological renal abnormalities with glomerular and tubulointerstitial fibrosis. Additionally, salt supplementation exacerbated renal injury, particularly tubular injury. These results suggest that UNx KK-Ay mice are useful models for advanced DKD and that salt exacerbates tubular damage in DKD.

An 11-Beta Hydroxysteroid Dehydrogenase Type 1 Inhibitor, JTT-654 Ameliorates Insulin Resistance and Non-obese Type 2 Diabetes.

11ß-Hydroxysteroid dehydrogenase type 1 (11ß-HSD1) is the only enzyme that converts inactive glucocorticoids to active forms and plays an important role in the regulation of glucocorticoid action in target tissues. JTT-654 is a selective 11ß-HSD1 inhibitor and we investigated its pharmacological properties in cortisone-treated rats and non-obese type 2 diabetic Goto-Kakizaki (GK) rats because Asians, including Japanese, are more likely to have non-obese type 2 diabetics. Systemic cortisone treatment increased fasting plasma glucose and insulin levels and impaired insulin action on glucose disposal rate and hepatic glucose production assessed by hyperinsulinemic-euglycemic clamp, but all these effects were attenuated by JTT-654 administration. Cortisone treatment also reduced basal and insulin-stimulated glucose oxidation in adipose tissue, increased plasma glucose levels after administration of the pyruvate, the substrate of gluconeogenesis, and increased liver glycogen content. Administration of JTT-654 also inhibited all of these effects. Cortisone treatment decreased basal and insulin-stimulated 2-deoxy-D-[1-3H]-glucose uptake in 3T3-L1 adipocytes and increased the release of free fatty acids and glycerol, a gluconeogenic substrate, from 3T3-L1 adipocytes, and JTT-654 significantly attenuated these effects. In GK rats, JTT-654 treatment significantly reduced fasting plasma glucose and insulin levels, enhanced insulin-stimulated glucose oxidation in adipose tissue, and suppressed hepatic gluconeogenesis as assessed by pyruvate administration. These results demonstrated that glucocorticoid was involved in the pathology of diabetes in GK rats, as in cortisone-treated rats, and that JTT-654 ameliorated the diabetic conditions. Our results suggest that JTT-654 ameliorates insulin resistance and non-obese type 2 diabetes by inhibiting adipose tissue and liver 11ß-HSD1.

Phosphorylation of αB-Crystallin Involves Interleukin-1ß-Mediated Intracellular Retention in Retinal Müller Cells: A New Mechanism Underlying Fibrovascular Membrane Formation.

Purpose: Chronic inflammation plays a pivotal role in the pathology of proliferative diabetic retinopathy (PDR), in which biological alterations of retinal glial cells are one of the key elements. The phosphorylation of αB-crystallin/CRYAB modulates its molecular dynamics and chaperone activity, and attenuates αB-crystallin secretion via exosomes. In this study, we investigated the effect of phosphorylated αB-crystallin in retinal Müller cells on diabetic mimicking conditions, including interleukin (IL)-1ß stimuli. Methods: Human retinal Müller cells (MIO-M1) were used to examine gene and protein expressions with real-time quantitative PCR, enzyme linked immunosorbent assay (ELISA), and immunoblot analyses. Cell apoptosis was assessed by Caspase-3/7 assay and TdT-mediated dUTP nick-end labeling staining. Retinal tissues isolated from the Spontaneously Diabetic Torii (SDT) fatty rat, a type 2 diabetic animal model with obesity, and fibrovascular membranes from patients with PDR were examined by double-staining immunofluorescence. Results: CRYAB mRNA was downregulated in MIO-M1 cells with the addition of 10 ng/mL IL-1ß; however, intracellular αB-crystallin protein levels were maintained. The αB-crystallin serine 59 (Ser59) residue was phosphorylated with IL-1ß application in MIO-M1 cells. Cell apoptosis in MIO-M1 cells was induced by CRYAB knockdown. Immunoreactivity for Ser59-phosphorylated αB-crystallin and glial fibrillary acidic protein was colocalized in glial cells of SDT fatty rats and fibrovascular membranes. Conclusions: The Ser59 phosphorylation of αB-crystallin was modulated by IL-1ß in Müller cells under diabetic mimicking inflammatory conditions, suggesting that αB-crystallin contributes to the pathogenesis of PDR through an anti-apoptotic effect.

GLUT9 as a potential drug target for chronic kidney disease: Drug target validation by a Mendelian randomization study.

Although chronic kidney disease (CKD) is recognized as a major public health concern, effective treatment strategies have yet to be developed. Identification and validation of drug targets are key issues in the development of therapeutic agents for CKD. Uric acid (UA), a major risk factor for gout, has also been suggested to be a risk factor for CKD, but the efficacy of existing urate-lowering therapies for CKD is controversial. We focused on five uric acid transporters (ABCG2, SLC17A1, SLC22A11, SLC22A12, SLC2A9) as potential drug targets and evaluated the causal association between serum UA levels and estimated glomerular filtration rate (eGFR) using single-SNP Mendelian Randomization. The results showed a causal association between genetically predicted changes in serum UA levels and eGFR when genetic variants were selected from the SLC2A9 locus. Estimation based on a loss-of-function mutation (rs16890979) showed that the changes in eGFR per unit increase in serum UA level was -0.0082 ml/min/1.73 m2 (95% CI -0.014 to -0.0025, P = 0.0051). These results indicate that SLC2A9 may be a novel drug target for CKD that preserves renal function through its urate-lowering effect.

Choline-deficient Diet-induced NAFLD Animal Model Recaptures Core Human Pathophysiology With Similar Gene Co-expression Networks.

BACKGROUND/AIM: Nonalcoholic fatty liver disease (NAFLD) is a wide spectrum of liver disorders ranging from simple steatosis to nonalcoholic steatohepatitis, cirrhosis, and hepatocellular carcinoma. Recently, the prevalence of NAFLD has dramatically increased, and treatment is urgently needed. Animal models are often used to understand the molecular mechanisms of disease development and progression, but their relevance to human diseases has not been fully understood. This study aimed to establish the usefulness of the animal model for preclinical research, we evaluated its relevance to human disease by gene expression analysis. MATERIALS AND METHODS: We performed weighted gene co-expression network analysis of liver tissues from a choline-deficient L-amino acid-defined (CDAA) diet-induced NAFLD animal model. In addition, module preservation analysis was conducted to evaluate similarity across species. RESULTS: Several modules were identified to be associated with disease severity, and their gene co-expression network was found to be preserved in the human NAFLD datasets. Of note, module brown (immune cell clusters involved in inflammatory responses) was positively associated with disease severity, and its gene co-expression network was highly preserved in the human datasets. Tyrobp, Laptm5 and Lgals3 were identified as hub genes in the brown module, and their increased expression was confirmed in the human datasets. CONCLUSION: CDAA diet-induced NAFLD animal model recaptured key aspects of human pathophysiology (especially immune cell functions) and is thought to be a powerful tool for understanding the molecular mechanisms of NAFLD development and progression.

Differences in the Effects of Pentobarbital Anesthetic and Combination of Medetomidine Hydrochloride, Midazolam, and Butorphanol Tartrate Anesthetic on Electroretinogram in Spontaneously Diabetic Torii Fatty Rats.

Purpose: The aim of this study was to investigate the effects of different anesthetic agents on electroretinograms (ERGs) in Spontaneously Diabetic Torii fatty rats (SDT fatty rats). Methods: The ERG recordings were measured under general anesthesia using pentobarbital or a combination of medetomidine hydrochloride, midazolam, and butorphanol (MMB) tartrate anesthesia in 12 9-week-old normal Sprague-Dawley rats (Jcl:SD rats) and 16 SDT fatty rats. Each animal model was divided into 2 groups, the pentobarbital group and MMB group. The amplitudes and peak times of the a- and b-waves and oscillatory potentials (OPs) were measured from 0.0001 candela per square meter (cd.s/m2) to 10.0 cd.s/m2. Results: The amplitude of the a-wave was significantly higher in the MMB group of Jcl:SD rats, but there was no significant difference in amplitude between the two groups of SDT fatty rats. There was no significant difference in the OP1 amplitude between both groups of Jcl:SD rats, but the OP1 amplitude was significantly higher in the MMB group of SDT fatty rats. The OP2 amplitude was significantly higher in the pentobarbital group in both the Jcl:SD rats and SDT fatty rats. There was no significant difference in the OP3 amplitude between the Jcl:SD and SDT fatty rat groups. The amplitude of the OP4 waves was significantly higher in the MMB group for both Jcl:SD and SDT fatty rats. There was no significant difference in the sums of the OP1 to OP4 (ΣOPs) amplitudes between the Jcl:SD and SDT fatty rat groups. There was no significant difference in the b-wave amplitude between the Jcl:SD rat groups, but the b-wave amplitude was significantly higher in the SDT fatty rats that received pentobarbital. The peak times for a-wave, OP1, OP2, OP3, OP4, and ΣOPs were significantly longer in the pentobarbital group of SD rats. The peak time of the b-wave was significantly longer in the MMB group of Jcl:SD rats, but the same result was obtained in the SDT fatty rats except that there was no significant difference in the a-wave. Conclusion: The overall ERG results vary depending on the anesthetic agent used. The OPs can be observed in detail when using MMB. Since the SDT fatty rat is a diabetic model animal, we recommend MMB as the anesthesia of choice when studying the OP waves in detail.

Establishment of a new nonalcoholic steatohepatitis model; Ovariectomy exacerbates nonalcoholic steatohepatitis-like pathology in diabetic rats.

An increasing number of patients worldwide are being diagnosed with nonalcoholic fatty liver disease and nonalcoholic steatohepatitis (NAFLD/NASH) because of the growing prevalence of obesity and metabolic disorders. The incidence of NAFLD is higher in postmenopausal women than in premenopausal women. The decline in the level of female hormones might have an effect on the deterioration of metabolism. In the present study, we investigated the potential of Spontaneously Diabetic Torii (SDT) fatty rats as a new animal model for NAFLD. We created a menopausal model by ovariectomy (OVX) in female rats. Sprague-Dawley (SD) rats, SDT rats, and SDT-fatty rats were divided into sham and OVX groups and maintained until 40 weeks of age. The results showed that OVX-induced weight gain was observed in SD and SDT rats. In addition, OVX-induced hepatic triglyceride accumulation was increased in all strains, and there was a significant increase in hepatic triglyceride levels in OVX-SDT fatty rats compared to those in Sham-SD rats. Furthermore, liver fibrosis was worsened in the OVX-SDT fatty rats. In addition, OVX-induced increase in blood ALT level was observed in SDT-fatty rats. Gene expression analysis showed OVX-induced upregulation of Srebp1 expression and downregulation of Pemt and Mttp in OVX rats. These results indicate that OVX-SDT fatty rats exhibit NASH with more severe hepatic fibrosis than untreated animals, suggesting that OVX-induced estrogen reduction may have enhanced lipid synthesis in the liver. It is also possible, although hypothetical, that OVX may decrease VLDL secretion, which may more strongly induce NASH.

Transient receptor potential vanilloid (TRPV) channels: Basal properties and physiological potential.

Transient receptor potential vanilloid (TRPV) channels are TRP homologs and have been classified into six subfamilies. They are unique mediators of sensory signals with multiple physiological effects and are potential targets for developing new therapies targeting human diseases. TRPV channels play crucial roles in normal physiological processes, and their dysfunction has been implicated in various disease states. Several small-molecule compounds, such as TRPV1 and TRPV3 antagonists, have been developed as novel analgesic agents. A better understanding of the physiological functions of TRPV channels would lead to progress in life science. In this review, we focus on various functions of TRPV channels, including pain sensing, temperature sensing, and metabolic control, as well as summarize the basal properties and pathophysiological contributions of six TRPV channels. Moreover, we discuss the pharmacological effects of endogenous and exogenous ligands on TRPV channels and related diseases.

The amelioration of T2DM rat femoral bone achieved by anti-osteoporosis of caprine CSN1S2 protein through bone morphogenetic protein signaling pathway.

We investigated the potential anti-glycation and anti-osteoporosis properties of Caprine milk CSN1S2 protein on the serum AGEs and sRAGE level, osteogenic factors expressions, femoral bone mesostructure, histomorphometry, and hydroxyapatite crystals changes in T2DM rats. Varying doses of Caprine milk CSN1S2 protein (0, 375, 750, and 1500 mg/kg BW) were used to treat the control and T2DM rats. We measured AGEs and sRAGE level; RUNX2, OSX, BMP2, and Caspase-3 expressions in rats using ELISA and immunohistochemistry, respectively. The mesostructure and histomorphometry of femoral bone was analyzed using SEM Microscope and BoneJ software, then hydroxyapatite crystal size was determined using SEM-XRD. T2DM rats showed a high level of AGEs and a low level of sRAGE, the RUNX2, OSX, and BMP2 expression was down regulated, BV, BV.TV, Tb.Th, Tb.Sp, increased and SMI levels declined, respectively. Vice versa, after administration of the CSN1S2 protein to T2DM rats, improvement in all levels of molecular and cellular markers was achieved. In the CSN1S2 highest dose, AGEs level declined and sRAGE level elevated in T2DM rats. The 375 and 750 mg/kgBW of CSN1S2 protein was able to upregulate the RUNX2, OSX, and BMP2 expression in T2DM rats, thus improving the normalization of osteoclasts and osteoblasts number. The whole dose of CSN1S2 triggered the thickening of trabecular bone wall, granule formation, and normalized the trabecular thickness (Tb.Th) parameter of T2DM rats. The hydroxyapatite crystal size was increased in the highest dose of CSN1S2-treated T2DM rats. This study indicated that CSN1S2 protein had a protective effect against osteoporosis in the T2DM rat bones by means of glycation pathway inhibition, bone histomorphometry and mesostructure improvement via bone morphometric protein signaling.

JTP-109192, a novel G protein-coupled receptor 119 agonist, prevents atherosclerosis by improving hypercholesterolaemia in congenic spontaneously hyperlipidaemic mice.

G protein-coupled receptor 119 (GPR119) expression in pancreatic ß-cells and intestinal L-cells is a potential therapeutic target for the treatment of type 2 diabetes. Previously, we have reported that the GPR119 agonist JTP-109192 improves glucose metabolism with single and repeated administration. Conversely, overexpression of the Gpr119 gene reportedly regulates cholesterol transporter expression in animal models, and a natural GPR119 agonist, oleoylethanolamide (OEA), improves atherosclerosis. Therefore, improving dyslipidaemia is considered a possible feature of GPR119 agonists. In the present study, the lipid-lowering effect of JTP-109192 was examined in BALB/c background spontaneously hyperlipidaemic (SHL) mice with repeated administration, once daily for 12 weeks. On repeated administration, JTP-109192 revealed a cholesterol-lowering effect and improved atherosclerosis following histopathological examination. With further investigation, the cholesterol-lowering effect and subsequent antiatherosclerotic effect of JTP-109192 was attributed to changes in intestinal cholesterol metabolism gene expression. Based on these results, JTP-109192 represents a new potential antihypercholesterolaemic agent for the treatment of dyslipidaemia.

The sphingosine-1-phosphate receptor modulator, FTY720, prevents the incidence of diabetes in Spontaneously Diabetic Torii rats.

The sphingosine-1-phosphate (S1P) receptor modulator regulates lymphocyte trafficking, resulting in its depletion from circulation, which ultimately causes immunosuppression. In this study, we investigated the preventive effect of fingolimod (FTY720) in the non-obese type 2 diabetic model, Spontaneously Diabetic Torii (SDT) rats. The S1P receptor modulator, FTY720 (0.3 mg/kg p.o.), was administered for 12 weeks to SDT rats from 5 to 17 weeks of age. Based on our findings, FTY720 could suppress the incidence of diabetes in SDT rats. Further, glucose intolerance was improved in FTY720-treated SDT rats at 14 weeks of age. Based on the haematological and histological analyses performed at 17 to 18 weeks of age, a decrease in lymphocytes and monocytes in the peripheral blood and a decrease in lymphocyte and atrophy in spleen occurred in the FTY720-treated SDT rats. Furthermore, the pancreatic changes, such as inflammation, atrophy, and fibrosis in islets observed in SDT rats were improved by FTY720 treatment. These findings suggest that the immunomodulatory effects of FTY720 reduced the pancreatic lesion in SDT rats, thereby demonstrating its preventive effect against diabetes. The development of diabetes in SDT rats is related to disorders of the immune system. However, the S1P receptor modulator may be useful for treating type 2 diabetes.

Diabetic Cataract in Spontaneously Diabetic Torii Fatty Rats.

Spontaneously Diabetic Torii (SDT) fatty rat is a novel animal model of type 2 diabetes with obesity. SDT fatty rats develop hyperglycemia, dyslipidemia, and other diabetic complications including ocular disorders; however, diabetic cataract formation in SDT fatty rats has not been fully investigated. The aim of the current study was to investigate the characteristics of cataract in the SDT fatty rats. The mean body weight of SDT fatty rats is larger than that of age-matched Sprague-Dawley (SD) rats and control animals until 8 weeks of age, and thereafter the growing speed decreased until the end of observation at 16 weeks of age. Blood glucose levels in SDT fatty rats were significantly higher than those in SD rats throughout the observational period. Slit-lamp examination revealed that no rats showed cataract formation at 5 weeks of age; however, SDT fatty rats gradually developed cortical cataract and posterior subcapsular cataract, both of which are the common types of cataract in patients with type 2 diabetes. The levels of glucose, sorbitol, and fructose were higher in the lens tissues of SDT fatty rats in comparison with that of SD rats. Furthermore, the level of 4-hydroxynonenal (4-HNE) was higher in the lens of SDT fatty rats than in that of SD rats. By contrast, total glutathione (GSH) concentration was lower in the lens of SDT fatty rats than in that of SD rats. The present study demonstrated that the cataractogenesis in SDT fatty rats resembled human diabetic cataract formation, indicating that SDT fatty rats serve as a potential animal model in researches on human cataract associated with type 2 diabetes and obesity.

Hyperglycemia contributes to the development of Leydig cell hyperplasia in male Spontaneously Diabetic Torii rats.

Spontaneously Diabetic Torii (SDT) rats are a well-known animal model of non-obese type 2 diabetes mellitus. Although this animal model has been studied extensively over the last decade, the incidence rates of Leydig cell hyperplasia and tumors in this model have not been reported. In this study, pathophysiological analyses of the testes were performed on male SDT rats, to understand the effect of insulin treatment on the development of Leydig cell hyperplasia and tumors and the expression of integrins and extracellular matrix proteins. Testicular Leydig cell hyperplasia and tumors were observed in SDT rats at 64 weeks of age but were rarely identified in Sprague-Dawley (SD) rats of the same age. Insulin treatment decreased plasma glucose and HbA1c levels, and interestingly, decreased the number of hyperplastic Leydig cell foci and Leydig cell tumors in treated animals. A similar reduction in the expression of Ki67 in these Leydig cell foci was also observed. In addition, insulin treatment decreased the expression of integrin α5, integrin ß1, integrin αvß3, fibronectin, and vitronectin in hyperplastic Leydig cell foci. These results suggest that insulin might decrease the incidence of Leydig cell hyperplasia by reducing Leydig cell proliferation and the expression of integrins and extracellular matrix proteins through the reduction of serum glucose concentrations in these animals.

Analysis of haemodynamics and angiogenic response to ischaemia in the obese type 2 diabetic model Spontaneously Diabetic Torii Leprfa (SDT fatty) rats.

Peripheral artery disease (PAD) is defined as peripheral blood flow impairment, especially in the legs, caused by atherosclerotic stenosis. The disease decreases quality of life because of intermittent claudication or necrosis of the leg. The hindlimb ischaemia model, in which ischaemia is induced by femoral artery ligation, is often utilized as a PAD model. In the hindlimb ischaemia model, nonmetabolic syndrome animals are mainly used. In this study, we investigated the usefulness of Spontaneously Diabetic Torii Leprfa (SDT fatty) rats, a new model for obese type 2 diabetes, as a new PAD animal model. We found that hindlimb blood flow in SDT fatty rats was significantly lower than that in Sprague-Dawley (SD) rats under nonischaemic conditions. Furthermore, SDT fatty rats showed a significantly higher plasma nitrogen oxide level, shorter prothrombin time, and shorter activated partial thromboplastin time than SD rats. In addition, we found that the change in blood flow 7 days after induction of hindlimb ischaemia and the number of Von Willebrand factor-positive vessels in gastrocnemius muscles were significantly lower in SDT fatty rats than in SD rats. These results suggest that excess production of reactive oxygen species and coagulation activation could be involved in lower blood flow in non-ischaemic rats and that decreased angiogenesis could be involved in the poor recovery of blood flow in SDT fatty rats with hindlimb ischaemia. Taken together, our results suggest that SDT fatty rats might be useful as a new model for PAD with metabolic syndrome.

A Novel TNF-α Converting Enzyme (TACE) Selective Inhibitor JTP-96193 Prevents Insulin Resistance in KK-Ay Type 2 Diabetic Mice and Diabetic Peripheral Neuropathy in Type 1 Diabetic Mice.

Tumor necrosis factor-α (TNF-α) converting enzyme/a disintegrin and metalloproteinase domain-containing protein 17 (TACE/ADAM17) is a key sheddase that releases TNF-α from its inactive precursor and is thought as a new drug target to inhibit TNF-α production. In the present study, pharmacological effects of a novel TACE selective inhibitor, JTP-96193, on type 2 diabetes and diabetic peripheral neuropathy (DPN) as its major complication was examined. Enzyme inhibitory activity of JTP-96193 on TACE and other ADAMs was measured in in vitro. High fat-induced obese mice and type 2 diabetic KK-Ay mice were used to evaluate the effect of JTP-96193 on insulin resistance. Finally, streptozotocin (STZ)-induced diabetic mice were treated with JTP-96193 to evaluate the sciatic motor nerve conduction velocities (MNCV). JTP-96193 selectively inhibited human TACE activity with IC50 value of 5.4 nM and showed more than 1800-fold selectivity against other matrix metalloproteinases. In mouse models of obesity and diabetes, JTP-96193 reduced the TNF-α release from the fat tissue and prevented development of diabetes and improved insulin resistance, respectively. Furthermore, JTP-96193 prevented delay of sciatic MNCV without any effects on blood glucose or insulin levels in STZ-induced diabetic mice. TACE inhibitor is effective on insulin resistance and DPN independent from glucose-lowering effect. These pharmacological properties of JTP-96193 may be helpful to treat type 2 diabetes accompanied by its microvascular complications.

Pathological Features of Diabetic Retinopathy in Spontaneously Diabetic Torii Fatty Rats.

OBJECTIVE: The Spontaneously Diabetic Torii (SDT) fatty rat, established by introducing the fa allele (obesity gene) of the Zucker fatty rat into the SDT rat genome, is a new model of obese type 2 diabetes. We studied the pathologic features of diabetic retinopathy (DR) in this animal. METHODS: The eyes of SDT fatty, SDT (controls), and Sprague Dawley (SD) rats (normal controls) were enucleated at 8, 16, 24, 32, and 40 weeks of age (n = 5-6 for each rat type at each age). The retinal thicknesses, numbers of retinal folds, and choroidal thicknesses were evaluated. Immunostaining for glial fibrillary acidic protein (GFAP) and vascular endothelial growth factor (VEGF) was performed. Quantitative analyses of the immunopositive regions were performed using a cell-counting algorithm. RESULTS: The retinas tended to be thicker in the SDT fatty rats and SDT rats than in the SD rats; the choroids tended to be thicker in the SDT fatty rats than in the SD rats. The retinal folds in the SDT fatty rats developed earlier and were more severe than in the SDT rats. Quantitative analyses showed that the GFAP- and VEGF-positive regions in the retinas of the SDT fatty rats were significantly larger than those of the SDT rats. CONCLUSIONS: SDT fatty rats developed more severe DR earlier than the SDT rats. The SDT fatty rats might be useful as a type 2 diabetes animal model to study DR.

Chronic treatment of JTP-109192, a novel G-protein coupled receptor 119 agonist, improves metabolic abnormalities in Zucker Fatty rats.

G-protein coupled receptor 119 (GPR119) expression in pancreatic ß-cells and intestinal L cells is a potential therapeutic target for treating type 2 diabetes. A natural GPR119 agonist oleoylethanolamide is well known to enhance a glucose-stimulated insulin secretion (GSIS) and glucagon-like peptide-1 (GLP-1) secretion by elevating intracellular cAMP levels. In the present study, a glucose lowering effect of the GPR119 agonist, JTP-109192 leading to improvement of insulin sensitivity was examined in Zucker Fatty (ZF) rats. We investigated the in vitro effects of JTP-109192 on GSIS in the rat pancreatic ß-cell line (INS1E) cells and on GLP-1 secretion in the murine enteroendocrine cell line (GLUTag) cells. We also investigated the effect of JTP-109192 on GSIS in Sprague-Dawley (SD) rats with single administration and its effect on glucose metabolism in ZF rats with repeated administration once daily for about 6 weeks. After repeated administration, the hyperinsulinaemic euglycaemic glucose clamp test was performed to evaluate insulin sensitivity. JTP-109192 increased intracellular cAMP levels (EC50 value: 3.6 nmol/L) and enhanced GSIS in the INS1E cells and GLP-1 secretion in GLUTag cells. In SD rats, a single administration of JTP-109192 enhanced GSIS at high blood glucose levels. The repeated administrations in ZF rats improved glucose metabolism without lack of drug efficacy (tachyphylaxis) and increased glucose infusion rates due to improvement of insulin sensitivity.