linagliptin and Insulin-Resistance

Dipeptidyl peptidase 4 (DPP4) inhibitors improve glycemic control by promoting GLP1-mediated glucose-dependent insulin secretion and suppression of glucagon. Sitagliptin and vildagliptin have been shown to improve insulin sensitivity in patients with type 2 diabetes mellitus (T2DM). However, these patients had uncontrolled blood glucose at inclusion; therefore, the improvement in insulin sensitivity observed in these studies could be attributed to the drug per se and/or reduction in glucotoxicity. This study examines the effect of linagliptin on insulin sensitivity and β-cell function in patients with well-controlled T2DM.. Thirty patients with T2DM of duration ≤5 years, and having HbA1c < 7.5% were randomized to receive linagliptin, voglibose or placebo (n = 10 each), and were followed up for 6 months. Insulin sensitivity was assessed by hyperinsulinemic-euglycemic clamp, and insulin secretory response was measured by basal (M. The median HbA1c of the study subjects at inclusion was 6.9% and there was no significant difference among the groups in terms of age, duration of diabetes, body mass index (BMI), HbA1c, insulin sensitivity, AUC of C-peptide and M. Linagliptin modestly improves glycemic profile in patients with well controlled T2DM; however, it may not have an effect on insulin sensitivity in these patients.. Retrospectively Registered in Clinicaltrials.gov (ID number, NCT02097342 ). Registered: March 27, 2014.

Topics: Adult; Blood Glucose; Diabetes Mellitus, Type 2; Double-Blind Method; Female; Glycated Hemoglobin; Humans; Hypoglycemic Agents; Inositol; Insulin Resistance; Insulin-Secreting Cells; Linagliptin; Male; Middle Aged; Postprandial Period

BACKGROUND This study aimed to evaluate the efficacy and safety of linagliptin (a novel dipeptidyl peptidase (DPP)-4 inhibitor) on glucose metabolism and β-cell function in Chinese patients with newly-diagnosed, drug-naïve type 2 diabetes mellitus (T2DM). MATERIAL AND METHODS Newly-diagnosed and drug-naïve T2DM patients were enrolled. After 4-week lifestyle modulation and 2-week placebo run-in, 57 patients were randomized to double-blind treatment with linagliptin (n=34) or placebo (n=23). The primary endpoint was the change from baseline in glycosylated hemoglobin A1c (HbA1c) after 24 weeks. Fasting plasma glucose (FPG), 2-h postprandial plasma glucose (2h-PPG), fasting insulin, proinsulin-to-insulin ratio, homeostasis model assessment of insulin resistance (HOMA-IR), and homeostasis model assessment of β-cell function (HOMA-β) were also evaluated. RESULTS Baseline characteristics were similar between the 2 groups. Compared with placebo, linagliptin therapy resulted in a significant decrease in HbA1C (-1.2±0.7% vs. -0.4±0.4%, P<0.001), FBG (-0.98±1.17 vs. -0.32±0.51 mmol/L, P=0.011, and 2h-PPG (-2.02±0.94 vs. -0.97±0.63 mmol/L, P<0.001). Significant differences were observed for the proinsulin/insulin ratio (P<0.001) and HOMA-β index (P=0.001). Rates of adverse events were similar between the 2 groups (30.3% vs. 27.3%). All adverse events were mild. One patient discontinued participation due to pregnancy. CONCLUSIONS Linagliptin treatment resulted in a significant and clinically meaningful improvement of glycemic control in drug-naïve Chinese patients with T2DM, as well as improved parameters of b-cell function. Linagliptin had an excellent safety profile.

Topics: Adult; Blood Glucose; Blood Pressure; Body Mass Index; Diabetes Mellitus, Type 2; Dipeptidyl-Peptidase IV Inhibitors; Double-Blind Method; Female; Glycated Hemoglobin; Homeostasis; Humans; Hyperglycemia; Hypoglycemic Agents; Insulin Resistance; Insulin-Secreting Cells; Life Style; Linagliptin; Male; Middle Aged; Postprandial Period; Time Factors

Alzheimer's disease (AD) is an age-related, multifactorial progressive neurodegenerative disorder manifested by cognitive impairment and neuronal death in the brain areas like hippocampus, yet the precise neuropathology of AD is still unclear. Continuous failure of various clinical trial studies demands the utmost need to explore more therapeutic targets against AD. Type 2 Diabetes Mellitus and neuronal insulin resistance due to serine phosphorylation of Insulin Receptor Substrate-1 at 307 exhibits correlation with AD. Dipeptidyl Peptidase-4 inhibitors (DPP-4i) have also indicated therapeutic effects in AD by increasing the level of Glucagon-like peptide-1 in the brain after crossing Blood Brain Barrier. The present study is hypothesized to examine Linagliptin, a DPP-4i in intracerebroventricular streptozotocin induced neurodegeneration, and neuroinflammation and hippocampal insulin resistance in rat model of AD. Following infusion on 1st and 3rd day, animals were treated orally with Linagliptin (0.513 mg/kg, 3 mg/kg, and 5 mg/kg) and donepezil (5 mg/kg) as a standard for 8 weeks. Neurobehavioral, biochemical and histopathological analysis was done at the end of treatment. Dose-dependently Linagliptin significantly reversed behavioral alterations done through locomotor activity (LA) and morris water maze (MWM) test. Moreover, Linagliptin augmented hippocampal GLP-1 and Akt-ser473 level and mitigated soluble Aβ (1-42), IRS-1 (s307), GSK-3β, TNF-α, IL-1β, IL-6, AchE and oxidative/nitrosative stress level. Histopathological analysis also exhibited neuroprotective and anti-amylodogenic effect in Hematoxylin and eosin and Congo red staining respectively. The findings of our study concludes remarkable dose-dependent therapeutic potential of Linagliptin against neuronal insulin resistance via IRS-1 and AD-related complication. Thus, demonstrates unique molecular mechanism that underlie AD.

Topics: Alzheimer Disease; Animals; Diabetes Mellitus, Type 2; Dipeptidyl-Peptidase IV Inhibitors; Disease Models, Animal; Glycogen Synthase Kinase 3 beta; Insulin Resistance; Linagliptin; Neuroinflammatory Diseases; Rats; Streptozocin

Studies have shown that the DPP-4 inhibitor was effective in improving skin damage in patients with psoriasis, but the exact mechanism was not known. To investigate the therapeutic effects of linagliptin in mice with type 2 diabetes mellitus (T2DM) with psoriasis and its possible therapeutic mechanisms. A total of 32 db/db mice and 16 db/m mice were randomly divided into six groups: normal group, psoriasis group, diabetes group, diabetes combined with psoriasis group, linagliptin-treated diabetes group, and linagliptin-treated diabetes combined with psoriasis group. The levels of serum fasting blood glucose, total cholesterol (TC), triglyceride (TG), high-density lipoprotein cholesterol, and low-density lipoprotein cholesterol were measured; the levels of serum FINS were determined by enzyme-linked immunoassay and the insulin resistance index was calculated. Basic parameters of diabetes, Psoriasis Area and Severity Index, histopathology of skin, the expression of interleukin (IL)-17A, IL-23, IL-22, and tumor necrosis factor (TNF)-α, and expression levels of measuring p-ERK, p-MAPK and p-nuclear factor kappa B (NF-κB) in skin tissues were measured. After treatment with linagliptin, insulin resistance, and TC and TG levels were reduced in mice with T2DM and psoriasis (p < .05). Moreover, the degree of epidermal tissue thickening, number of keratinized layers, and inflammatory cell infiltration were also reduced (p < .05), as well as the expression levels of inflammatory factors: TNF-α, IL-1β, IL-17A, IL-23, and p-P38/P38, p-ERK/ERK, p-P65/P65 proteins (p < .05). Linagliptin significantly reduced the extent of skin lesions and skin inflammation. The underlying mechanism of this compound may be related to the inhibition of MAPK/NF-κB inflammatory pathways and the consequential improvement of insulin resistance.Significance Statement: In this study, we evaluated the therapeutic effect of the DPP-4 inhibitor linagliptin using a murine model of type 2 diabetes combined with psoriasis, and its potential mechanisms of action were further explored. The results of this study will help to uncover the pathogenesis of type 2 diabetes and psoriasis and, more importantly, provide a theoretical basis for the search for safe and effective drugs in the treatment of this specific patient population.

Topics: Animals; Cholesterol; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Dipeptidyl-Peptidase IV Inhibitors; Hypoglycemic Agents; Imiquimod; Insulin Resistance; Interleukin-23; Linagliptin; Mice; NF-kappa B; Psoriasis; Tumor Necrosis Factor-alpha

In contrast to Western population, glucagon-like peptide-1 (GLP-1) levels are preserved in some East Asian population with type 2 diabetes (T2D), explaining why dipeptidyl peptidase-IV (DPP-IV) inhibitors are more effective in East Asians. We assessed whether differences in endogenous GLP-1 levels resulted in different treatment responses to DPP-IV inhibitors in prediabetes and T2D.. A prospective 12-week study using linagliptin 5mg once daily in 50 subjects (28 prediabetes and 22 T2D) who were stratified into high versus low fasting GLP-1 groups. A 75-g oral glucose tolerance test (OGTT) was performed at week 0 and 12. Primary outcomes were changes in HbA1c, fasting and post-OGTT glucose after 12 weeks. Secondary outcomes included changes in insulin resistance and beta cell function indices.. There was a greater HbA1c reduction in subjects with high GLP-1 compared to low GLP-1 levels in both the prediabetes and T2D populations [least-squares mean (LS-mean) change of -0.33% vs. -0.11% and -1.48% vs. -0.90% respectively)]. Linagliptin significantly reduced glucose excursion by 18% in high GLP-1 compared with 8% in low GLP-1 prediabetes groups. The reduction in glucose excursion was greater in high GLP-1 compared to low GLP-1 T2D by 30% and 21% respectively. There were significant LS-mean between-group differences in fasting glucose (-0.95 mmol/L), 2-hour glucose post-OGTT (-2.4 mmol/L) in the high GLP-1 T2D group. Improvement in insulin resistance indices were seen in the high GLP-1 T2D group while high GLP-1 prediabetes group demonstrated improvement in beta cell function indices. No incidence of hypoglycemia was reported.. Linagliptin resulted in a greater HbA1c reduction in the high GLP-1 prediabetes and T2D compared to low GLP-1 groups. Endogenous GLP-1 level play an important role in determining the efficacy of DPP-IV inhibitors irrespective of the abnormal glucose tolerance states.

Topics: Blood Glucose; Diabetes Mellitus, Type 2; Dipeptidyl-Peptidase IV Inhibitors; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; Glucagon-Like Peptide 1; Glycated Hemoglobin; Humans; Insulin Resistance; Linagliptin; Prediabetic State; Prospective Studies

Alzheimer's disease (AD) is the most devastating neurodegenerative disorder, accounting over 46 million cases of dementia globally. Evidence supports that Brain Insulin Resistance (BIR) due to serine phosphorylation of Insulin Receptor Substrate-1 (IRS-1) has an association with AD. GLP-1 an incretin hormone, rapidly degraded by Dipeptidyl Peptidase-4 (DPP-4) has also confirmed its efficacious role in AD. Linagliptin, a DPP-4 inhibitor is hypothesized to increase GLP-1 level, which then crosses Blood Brain Barrier (BBB), decreases Amyloid-beta (Aβ) and insulin resistance in hippocampus. Thus, the present study was designed to evaluate Linagliptin in Aβ (1-42) peptides induced rat model of AD. Following 1 week of induction, rats were administered with Linagliptin (0.513 mg/kg, 3 mg/kg, and 5 mg/kg) orally for 8 weeks and donepezil (5 mg/kg) as a reference standard. At the end of scheduled treatment neurobehavioral parameters were assessed. After this, rats were sacrificed, hippocampus was isolated from the whole brain for histopathological analysis and biochemical parameters estimation. Linagliptin dose-dependently and significantly reversed motor and cognitive impairment, assessed through locomotor activity (LA) and Morris water maze (MWM) test respectively. Moreover, Linagliptin augmented GLP-1 level and attenuated soluble Aβ (1-42), IRS-1 (s307), GSK-3β, TNF-α, IL-1β, IL-6, AchE and oxidative/nitrosative stress level in hippocampus. H&E and Congo red staining also exhibited neuroprotective and anti-amylodogenic effect respectively. Our study findings implies the significant effect of Linagliptin in reversing the behavioural and biochemical deficits by altering Aβ (1-42) and BIR via IRS-1 confirming one of the mechanism underlying the pathophysiology of AD.

Topics: Alzheimer Disease; Amyloid beta-Peptides; Animals; Brain; Dipeptidyl-Peptidase IV Inhibitors; Insulin Receptor Substrate Proteins; Insulin Resistance; Linagliptin; Male; Nerve Degeneration; Peptide Fragments; Rats; Rats, Wistar

To investigate the effects of linagliptin treatment on hepatic energy metabolism and ER stress in high-fat-fed C57BL/6 mice.. Forty male C57BL/6 mice, three months of age, received a control diet (C, 10% of lipids as energy, n = 20) or high-fat diet (HF, 50% of lipids as energy, n = 20) for 10 weeks. The groups were randomly subdivided into four groups to receive linagliptin, for five weeks, at a dose of 30 mg/kg/day added to the diets: C, C-L, HF, and HF-L groups.. The HF group showed higher body mass, total and hepatic cholesterol levels and total and hepatic triacylglycerol levels than the C group, all of which were significantly diminished by linagliptin in the HF-L group. The HF group had higher hepatic steatosis than the C group, whereas linagliptin markedly reduced the hepatic steatosis (less 52%, P < 0.001). The expression of Sirt1 and Pgc1a was more significant in the HF-L group than in the HF group. Linagliptin also elicited enhanced GLP-1 concentrations and a reduction in the expression of the lipogenic genes Fas and Srebp1c. Besides, HF-L showed a reduction in the genes related to endoplasmic reticulum stress Chop, Atf4, and Gadd45 coupled with reduced apoptotic nuclei immunostaining.. Linagliptin caused a marked reduction in hepatic steatosis as a secondary effect of its glucose-lowering property. NAFLD countering involved reduced lipogenesis, increased beta-oxidation, and relief in endoplasmic reticulum stress, leading to reduced apoptosis and better preservation of the hepatic structure. Therefore, linagliptin may be used, preferably in diabetic patients, to avoid the progression of hepatic steatosis.

Topics: Animals; Apoptosis; Biomarkers; Blood Glucose; Body Weight; Carbohydrate Metabolism; Diet, High-Fat; Eating; Endoplasmic Reticulum Stress; Fasting; Feeding Behavior; Glucagon-Like Peptide 1; Insulin; Insulin Resistance; Linagliptin; Lipid Droplets; Lipids; Lipogenesis; Liver; Male; Mice, Inbred C57BL; Non-alcoholic Fatty Liver Disease; Oxidation-Reduction; Perilipin-2; Vascular Endothelial Growth Factor A

Liver fibrosis is a common complication of diabetes mellitus, with a major global public health concern. Linagliptin, a dipeptidyl peptidase-4 inhibitor (DPP-4), is classically used to treat type 2 diabetes mellitus and improves insulin resistance. Additional potential influences of linagliptin on liver fibrosis are still unclear. The present study was undertaken to investigate the therapeutic credit of linagliptin in hepatic fibrosis induced by a high-fat diet (HFD) and streptozotocin (STZ) in rats. Moreover, the mechanisms underline its anti-fibrotic effect were explored. To induce liver fibrosis with T2DM; male Sprague-Dawley albino rats were fed on a high-fat high-sucrose diet for 28 days then exposed to a single dose of STZ (30 mg/kg, IP). After two days of STZ injection, a diabetes confirmation test was done and all diabetic rats were constantly fed on HFD for thirty days with or without treatment with linagliptin (6 mg/kg). Hepatotoxicity markers, lipid profile screening, insulin signaling, inflammatory cytokines (TNF-α, IL-6, NF-κB p65), fibrosis markers (Collagen, α-SMA, TGF-β1) and histopathological studies including hematoxylin and eosin (H&E) as well Masson's trichrome stains were performed. In our preliminary study, linagliptin at a dose of 6 mg/kg was chosen as the optimum anti-diabetic dose in rats challenged with STZ. Linagliptin significantly improved insulin sensitivity and lipid profile and reduced inflammatory mediators, and collagen depositions in rats with liver fibrosis and T2DM. In conclusion, above and beyond its anti-diabetic effect, this study introduced linagliptin as a promising option for preventing the pathological progression of liver fibrosis associated with T2DM.

Topics: Animals; Blood Glucose; Collagen; Diabetes Mellitus, Experimental; Diet, High-Fat; Dipeptidyl-Peptidase IV Inhibitors; Disease Progression; Inflammation Mediators; Insulin; Insulin Resistance; Linagliptin; Lipids; Liver; Liver Cirrhosis; Male; Obesity; Rats, Sprague-Dawley

Diabetic nephropathy has a significant socioeconomic impact, but its mechanism is unclear and needs to be examined. Hibiscus sabdariffa polyphenols (HPE) inhibited high glucose-induced angiotensin II receptor-1 (AT-1), thus attenuating renal epithelial mesenchymal transition (EMT). Recently, we reported HPE inhibited dipeptidyl-peptidase-4 (DPP-4, the enzyme degrades type 1 glucagon-like peptide (GLP-1)), which mediated insulin resistance signals leading to EMT. Since free fatty acids can realistically bring about insulin resistance, using the palmitate-stimulated cell model in contrast with type 2 diabetic rats, in this study we examined if insulin resistance causes renal EMT, and the preventive effect of HPE. Our findings reveal that palmitate hindered 30% of glucose uptake. Treatment with 1 mg mL(-1) of HPE and the DPP-4 inhibitor linagliptin completely recovered insulin sensitivity and palmitate-induced signal cascades. HPE inhibited DPP-4 activity without altering the levels of DPP-4 and the GLP-1 receptor (GLP-1R). HPE decreased palmitate-induced phosphorylation of Ser307 of insulin receptor substrate-1 (pIRS-1 (S307)), AT-1 and vimentin, while increasing phosphorylation of phosphatidylinositol 3-kinase (pPI3K). IRS-1 knockdown revealed its essential role in mediating downstream AT-1 and EMT. In type 2 diabetic rats, it suggests that HPE concomitantly decreased the protein levels of DPP-4, AT-1, vimentin, and fibronectin, but reversed the in vivo compensation of GLP-1R. In conclusion, HPE improves insulin sensitivity by attenuating DPP-4 and the downstream signals, thus decreasing AT-1-mediated tubular-interstitial EMT. HPE could be an adjuvant to prevent diabetic nephropathy.

Topics: Animals; Cell Differentiation; Cell Line; Diabetes Mellitus, Type 2; Dipeptidyl Peptidase 4; Epithelial Cells; Gene Expression Regulation; Glucagon-Like Peptide-1 Receptor; Hibiscus; Humans; Insulin Receptor Substrate Proteins; Insulin Resistance; Kidney; Linagliptin; Mesenchymal Stem Cells; Palmitates; Polyphenols; Rats; Vimentin

Combining different drug classes to improve glycemic control is one treatment strategy for type 2 diabetes. The effects on insulin sensitivity of long-term treatment with the sodium glucose co-transporter 2 (SGLT2) inhibitor empagliflozin alone or co-administered with the dipeptidyl peptidase-4 inhibitor linagliptin (both approved antidiabetes drugs) were investigated in mice using euglycemic-hyperinsulinemic clamps.. db/db mice (n=15/group) were treated for 8weeks with 10mg/kg/day empagliflozin monotherapy, 10mg/kg/day empagliflozin plus 3mg/kg/day linagliptin combination therapy, or 3mg/kg/day linagliptin monotherapy. At the end of the study, euglycemic-hyperinsulinemic clamp studies were performed 4days after the last dose of treatment.. HbA1c and 2-hour fasting glucose concentrations were improved with empagliflozin monotherapy and combination therapy compared with vehicle and linagliptin monotherapy. During the clamp, glucose disposal rates increased and hepatic glucose production decreased with empagliflozin monotherapy and combination therapy compared with vehicle and linagliptin monotherapy. Glucose uptake in liver and kidney was higher with empagliflozin monotherapy and combination therapy compared with vehicle; glucose uptake into both muscle and adipose tissue was only affected by linagliptin treatment. Empagliflozin and combination therapy altered the expression of genes involved in the inflammatory response, fatty acid synthesis and oxidation.. These findings suggest that the insulin-sensitizing effects of SGLT2 inhibition contribute to improvements in glycemic control in insulin-resistant states.

Topics: Animals; Benzhydryl Compounds; Female; Glucose; Glucosides; Glycosides; Hypoglycemic Agents; Insulin Resistance; Insulin-Secreting Cells; Linagliptin; Lipid Metabolism; Mice; Sodium-Glucose Transporter 2 Inhibitors

Dipeptidyl peptidase 4 (DPP-4) cleaves a large number of chemokine and peptide hormones involved in the regulation of the immune system. Additionally, DPP-4 may also be involved in macrophage-mediated inflammation and insulin resistance. Thus, the current study investigated the effect of linagliptin, an inhibitor of DPP-4, on macrophage migration and polarization in white adipose tissue (WAT) and liver of high-fat diet-induced obese (DIO) mice. DPP-4(+) macrophages in lean and obese mice were quantified by fluorescence-activated cell sorting (FACS) analysis. DPP-4 was predominantly expressed in F4/80(+) macrophages in crown-like structures compared with adipocytes in WAT of DIO mice. FACS analysis also revealed that, compared with chow-fed mice, DIO mice exhibited a significant increase in DPP-4(+) expression in cells within adipose tissue macrophages (ATMs), particularly M1 ATMs. Linagliptin showed a greater DPP-4 inhibition and antioxidative capacity than sitagliptin and reduced M1-polarized macrophage migration while inducing an M2-dominant shift of macrophages within WAT and liver, thereby attenuating obesity-induced inflammation and insulin resistance. Loss of macrophage inflammatory protein-1α, a chemokine and DPP-4 substrate, in DIO mice abrogated M2 macrophage-polarizing and insulin-sensitizing effects of linagliptin. Therefore, the inhibition of DPP-4 by linagliptin reduced obesity-related insulin resistance and inflammation by regulating M1/M2 macrophage status.

Topics: Adipose Tissue; Animals; Cell Movement; Cells, Cultured; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Flow Cytometry; Inflammation; Insulin Resistance; Linagliptin; Macrophages; Male; Mice; Mice, Inbred C57BL; Obesity; Sitagliptin Phosphate

The epithelial to mesenchymal transition (EMT) is important in renal fibrosis. Ser307 phosphorylation of insulin receptor substrate-1 (IRS-1 (S307)) is a hallmark of insulin resistance. We report that polyphenol extracts of Hibiscus sabdariffa (HPE) ameliorate diabetic nephropathy and EMT. Recently it has been observed that type 4 dipeptidyl peptidase (DPP-4) inhibitor linagliptin is effective for treating type 2 diabetes and albuminuria. We investigated if DPP-4 and insulin resistance are involved in renal EMT and explored the role of HPE. In high glucose-stimulated tubular cells, HPE, like linagliptin, inhibited DPP-4 activation, thereby regulating vimentin (EMT marker) and IRS-1 (S307). IRS-1 knockdown revealed its essential role in mediating downstream EMT. In type 2 diabetic rats, pIRS-1 (S307) abundantly surrounds the tubular region, with increased vimentin in kidney. Both the expressions were reduced by HPE. In conclusion, HPE exerts effects similar to those of linagliptin, which improves insulin resistance and EMT, and could be an adjuvant to prevent diabetic nephropathy.

Topics: Animals; Cells, Cultured; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Epithelial-Mesenchymal Transition; Glucose; Hibiscus; Insulin Receptor Substrate Proteins; Insulin Resistance; Kidney; Linagliptin; Male; Phosphorylation; Polyphenols; Purines; Quinazolines; Rats, Sprague-Dawley; Vimentin

Diastolic dysfunction is a prognosticator for future cardiovascular events that demonstrates a strong correlation with obesity. Pharmacological inhibition of dipeptidylpeptidase-4 (DPP-4) to increase the bioavailability of glucagon-like peptide-1 is an emerging therapy for control of glycemia in type 2 diabetes patients. Accumulating evidence suggests that glucagon-like peptide-1 has insulin-independent actions in cardiovascular tissue. However, it is not known whether DPP-4 inhibition improves obesity-related diastolic dysfunction. Eight-week-old Zucker obese (ZO) and Zucker lean rats were fed normal chow diet or diet containing the DPP-4 inhibitor, linagliptin (LGT), for 8 weeks. Plasma DPP-4 activity was 3.3-fold higher in ZO compared with Zucker lean rats and was reduced by 95% with LGT treatment. LGT improved echocardiographic and pressure volume-derived indices of diastolic function that were impaired in ZO control rats, without altering food intake or body weight gain during the study period. LGT also blunted elevated blood pressure progression in ZO rats involving improved skeletal muscle arteriolar function, without reducing left ventricular hypertrophy, fibrosis, or oxidative stress in ZO hearts. Expression of phosphorylated- endothelial nitric oxide synthase (eNOS)(Ser1177), total eNOS, and sarcoplasmic reticulum calcium ATPase 2a protein was elevated in the LGT-treated ZO heart, suggesting improved Ca(2+) handling. The ZO myocardium had an abnormal mitochondrial sarcomeric arrangement and cristae structure that were normalized by LGT. These studies suggest that LGT reduces blood pressure and improves intracellular Cai(2+) mishandling and cardiomyocyte ultrastructure, which collectively result in improvements in diastolic function in the absence of reductions in left ventricular hypertrophy, fibrosis, or oxidative stress in insulin-resistant ZO rats.

Topics: Animals; Blood Pressure; Body Weight; Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; Eating; Insulin Resistance; Linagliptin; Male; Myocardium; Nitric Oxide Synthase Type III; Purines; Quinazolines; Rats; Rats, Zucker; Sarcoplasmic Reticulum Calcium-Transporting ATPases

Linagliptin (TRADJENTA™) is a selective dipeptidyl peptidase-4 (DPP-4) inhibitor. DPP-4 inhibition attenuates insulin resistance and improves peripheral glucose utilization in humans. However, the effects of chronic DPP-4 inhibition on insulin sensitivity are not known. The effects of long-term treatment (3-4 weeks) with 3 mg/kg/day or 30 mg/kg/day linagliptin on insulin sensitivity and liver fat content were determined in diet-induced obese C57BL/6 mice. Chow-fed animals served as controls. DPP-4 activity was significantly inhibited (67-89%) by linagliptin (P<0.001). Following an oral glucose tolerance test, blood glucose concentrations (measured as area under the curve) were significantly suppressed after treatment with 3 mg/kg/day (-16.5% to -20.3%; P<0.01) or 30 mg/kg/day (-14.5% to -26.4%; P<0.05) linagliptin (both P<0.01). Liver fat content was significantly reduced by linagliptin in a dose-dependent manner (both doses P<0.001). Diet-induced obese mice treated for 4 weeks with 3 mg/kg/day or 30 mg/kg/day linagliptin had significantly improved glycated hemoglobin compared with vehicle (both P<0.001). Significant dose-dependent improvements in glucose disposal rates were observed during the steady state of the euglycemic-hyperinsulinemic clamp: 27.3 mg/kg/minute and 32.2 mg/kg/minute in the 3 mg/kg/day and 30 mg/kg/day linagliptin groups, respectively; compared with 20.9 mg/kg/minute with vehicle (P<0.001). Hepatic glucose production was significantly suppressed during the clamp: 4.7 mg/kg/minute and 2.1 mg/kg/minute in the 3 mg/kg/day and 30 mg/kg/day linagliptin groups, respectively; compared with 12.5 mg/kg/minute with vehicle (P<0.001). In addition, 30 mg/kg/day linagliptin treatment resulted in a significantly reduced number of macrophages infiltrating adipose tissue (P<0.05). Linagliptin treatment also decreased liver expression of PTP1B, SOCS3, SREBP1c, SCD-1 and FAS (P<0.05). Other tissues like muscle, heart and kidney were not significantly affected by the insulin sensitizing effect of linagliptin. Long-term linagliptin treatment reduced liver fat content in animals with diet-induced hepatic steatosis and insulin resistance, and may account for improved insulin sensitivity.

Topics: Adipose Tissue; Animals; Diet; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Fatty Liver; Female; Glucose; Glucose Clamp Technique; Glucose Tolerance Test; Insulin; Insulin Resistance; Linagliptin; Liver; Mice; Mice, Inbred C57BL; Obesity; Purines; Quinazolines