Prophylactic treatment with telmisartan induces tissue-specific gene modulation favoring normal glucose homeostasis in Cohen-Rosenthal diabetic hypertensive rats

Effects of telmisartan on metabolic syndrome components: a comprehensive review

Telmisartan is an antagonist of the angiotensin II receptor used in the management of hypertension (alone or in combination with other antihypertensive agents. It belongs to the drug class of angiotensin II receptor blockers (ARBs). Among drugs of this class, telmisartan shows particular pharmacologic properties, including a longer half-life than any other angiotensin II receptor blockers that bring higher and persistent antihypertensive activity. In hypertensive patients, telmisartan has superior efficacy than other antihypertensive drugs (losartan, valsartan, ramipril, atenolol, and perindopril) in controlling blood pressure, especially towards the end of the dosing interval. Telmisartan has a partial PPARγ-agonistic effect whilst does not have the safety concerns of full agonists of PPARγ receptors (thiazolidinediones). Moreover, telmisartan has an agonist activity on PPARα and PPARδ receptors and modulates the adipokine levels. Thus, telmisartan could be considered as a suitable alternative option, with multi-benefit for all components of metabolic syndrome including hypertension, diabetes mellitus, obesity, and hyperlipidemia. This review will highlight the role of telmisartan in metabolic syndrome and the main mechanisms of action of telmisartan are discussed and summarized. Many studies have demonstrated the useful properties of telmisartan in the prevention and improving of metabolic syndrome and this well-tolerated drug can be greatly proposed in the treatment of different components of metabolic syndrome. However, larger and long-duration studies are needed to confirm these findings in long-term observational studies and prospective trials and to determine the optimum dose of telmisartan in metabolic syndrome.

Beneficial Effect of the SGLT2 Inhibitor Empagliflozin on Glucose Homeostasis and Cardiovascular Parameters in the Cohen Rosenthal Diabetic Hypertensive (CRDH) Rat

The effectiveness of empagliflozin (EMPA), a sodium glucose cotransporter type 2 inhibitor, on the kidney, pancreas, and heart was investigated in the Cohen Rosenthal diabetic hypertensive rat model (CRDH rat). Six-week-old CRDH male rats were fed a sugar diet (SD) and treated with the compound EMPA (group Drug/SD) or respective comparator with vehicle (group Veh/SD). A control group was fed a regular diet without treatment (group Veh/P). Preventive treatment with EMPA was measured during 4 months of follow-up. The treatment effect was evaluated according to results observed after 4 months in group Drug/SD when compared to those in group Veh/SD. Significant effect resulted in the following parameters: enhancement of urinary glucose excretion in association with diuresis; amelioration of postprandial hyperglycemia and fasting blood glucose levels; and decrease in calculated Homeostatic Model Assessment of Insulin Resistance (HOMA-IR) as well as lower systolic and diastolic blood pressures. At the end of treatment, EMPA preserved nephrin integrity in the kidney, reduced proteinuria, and prevented diabetes-induced damage to glomerular diaphragm structure. In the pancreas, EMPA demonstrated an impressive decrease in fatty infiltration and atrophy. Blood pressure was significantly reduced in the EMPA-treated group (15 ± 5.1 mm Hg, P < .05) in contrast to the vehicle and control groups. Finally, compared to controls, EMPA significantly reduced left ventricle (LV) mass and LV systolic dilatation, according to 2-dimensional echocardiography. The importance of the study lies in demonstrating the efficacy of an antidiabetic drug with beneficial effects on blood pressure, weight, kidney, and pancreas and a positive effect on the heart.

Differential effects of angiotensin receptor blockers on pancreatic islet remodelling and glucose homeostasis in diet-induced obese mice

Obesity leads to adverse endocrine pancreas remodelling, reduced islet lifespan and early type 2 diabetes onset. AT1R blockade shows beneficial pleiotropic effects. This study sought to compare the effects of losartan and telmisartan on pancreatic islets remodelling and glucose homeostasis in diet-induced obese mice. High-fat diet yielded overweight, insulin resistance, islet apoptosis and hypertrophy. Suitable insulin levels and preserved endocrine pancreas structure were correlated to adequate AKT-FOXO1 pathway functioning in losartan-treated animals. Conversely, telmisartan yielded enhanced PDX1 and GLP-1 islet expression along with greater GLP-1 levels, with the consequent better islet glucose sensing and uptake. Greater islet vascularisation coupled with reduced apoptosis and macrophage infiltration seems to underlie the beneficial findings in both treatments. In conclusion, these results provide compelling evidence that two antihypertensive drugs (telmisartan and losartan) ameliorate pancreatic islet structure, glucose handling, and vascularisation in obese mice. Although only telmisartan countered overweight, both drugs yielded reduced apoptosis and islet preservation, with translational potential.

Telmisartan-mediated metabolic profile conferred brain protection in diabetic hypertensive rats as evidenced by magnetic resonance imaging, behavioral studies and histology

Type 2 diabetes and hypertension are associated with cognitive dysfunction that includes pathological changes in brain tissue. It was speculated that the beneficial hypotensive effect of telmisartan, an angiotensin receptor 1 blocker, and its unique hypoglycemic effect due to its PPARγ-activation, could ameliorate the ​ pathological changes in the brain​ that accompany​ these diseases. We examined the effect of telmisartan on brain changes in magnetic resonance imaging (MRI) T2-weighted scans, and behavioral and histological findings in the Cohen-Rosenthal Diabetic Hypertensive (CRDH) rat. Baseline and post-treatment values with telmisartan/vehicle (3 months) of blood pressure, blood glucose levels, behavioral tests, brain MRI scanning and immunohistological staining were obtained. Telmisartan significantly lowered blood pressure and blood glucose levels; induced consistent T2 reduction in specific gray and white regions including hippocampus, corpus callosum, amygdala and cortical regions; and significantly improved performance on behavioral tasks. Immunohistological analysis of the brain revealed significant amelioration of diabetes/hypertension-induced changes in white matter regions and microglia, evidenced by preserved myelin (LBF marker), and improved microglial neuronal markers GFAP, GAP43 and Iba1 expression. In conclusion, the behavioral performance, longitudinal MRI study and histology staining revealed the protective effects of telmisartan on brain microstructure and cognitive function.

Angiotensin II type 1 receptor antagonists in animal models of vascular, cardiac, metabolic and renal disease

We have reviewed the effects of angiotensin II type 1 receptor antagonists (ARBs) in various animal models of hypertension, atherosclerosis, cardiac function, hypertrophy and fibrosis, glucose and lipid metabolism, and renal function and morphology. Those of azilsartan and telmisartan have been included comprehensively whereas those of other ARBs have been included systematically but without intention of completeness. ARBs as a class lower blood pressure in established hypertension and prevent hypertension development in all applicable animal models except those with a markedly suppressed renin-angiotensin system; blood pressure lowering even persists for a considerable time after discontinuation of treatment. This translates into a reduced mortality, particularly in models exhibiting marked hypertension. The retrieved data on vascular, cardiac and renal function and morphology as well as on glucose and lipid metabolism are discussed to address three main questions: 1. Can ARB effects on blood vessels, heart, kidney and metabolic function be explained by blood pressure lowering alone or are they additionally directly related to blockade of the renin-angiotensin system? 2. Are they shared by other inhibitors of the renin-angiotensin system, e.g. angiotensin converting enzyme inhibitors? 3. Are some effects specific for one or more compounds within the ARB class? Taken together these data profile ARBs as a drug class with unique properties that have beneficial effects far beyond those on blood pressure reduction and, in some cases distinct from those of angiotensin converting enzyme inhibitors. The clinical relevance of angiotensin receptor-independent effects of some ARBs remains to be determined.

Direct renin inhibition modulates insulin resistance in caveolin-1-deficient mice

OBJECTIVE

To test the hypothesis that aliskiren improves the metabolic phenotype in a genetic mouse model of the metabolic syndrome (the caveolin-1 (cav-1) knock out (KO) mouse).

MATERIALS/METHODS

Eleven-week-old cav-1 KO and genetically matched wild-type (WT) mice were randomized to three treatment groups: placebo (n=8/group), amlodipine (6 mg/kg/day, n=18/ group), and aliskiren (50 mg/kg/day, n=18/ group). After three weeks of treatment, all treatment groups were assessed for several measures of insulin resistance (fasting insulin and glucose, HOMA-IR, and the response to an intraperitoneal glucose tolerance test (ipGTT)) as well as for triglyceride levels and the blood pressure response to treatment.

RESULTS

Treatment with aliskiren did not affect the ipGTT response but significantly lowered the HOMA-IR and insulin levels in cav-1 KO mice. However, treatment with amlodipine significantly degraded the ipGTT response, as well as the HOMA-IR and insulin levels in the cav-1 KO mice. Aliskiren also significantly lowered triglyceride levels in the cav-1 KO but not in the WT mice. Moreover, aliskiren treatment had a significantly greater effect on blood pressure readings in the cav-1 KO vs. WT mice, and was marginally more effective than amlodipine.

CONCLUSIONS

Our results support the hypothesis that aliskiren reduces insulin resistance as indicated by improved HOMA-IR in cav-1 KO mice whereas amlodipine treatment resulted in changes consistent with increased insulin resistance. In addition, aliskiren was substantially more effective in lowering blood pressure in the cav-1 KO mouse model than in WT mice and marginally more effective than amlodipine.