Effects of chronic combined treatment with captopril and pravastatin on the progression of insulin resistance and cardiovascular alterations in an experimental model of obesity in dogs

Insulin resistance in ischemic stroke: Mechanisms and therapeutic approaches

The pathological condition of insulin resistance prevents the neuroprotective effects of insulin. Numerous studies have demonstrated that insulin resistance, as an independent risk factor for ischemic stroke, accelerates the formation of thrombosis and promotes the development of atherosclerosis, both of which are major mechanisms of ischemic stroke. Additionally, insulin resistance negatively affects the prognosis of patients with ischemic stroke regardless of whether the patient has diabetes, but the mechanisms are not well studied. We explored the association between insulin resistance and the primary mechanisms of brain injury in ischemic stroke (inflammation, oxidative stress, and neuronal damage), looking for potential causes of poor prognosis in patients with ischemic stroke due to insulin resistance. Furthermore, we summarize insulin resistance therapeutic approaches to propose new therapeutic directions for clinically improving prognosis in patients with ischemic stroke.

Cardiac remodeling in obesity

The dramatic increase in the prevalence of obesity and its strong association with cardiovascular disease have resulted in unprecedented interest in understanding the effects of obesity on the cardiovascular system. A consistent, but puzzling clinical observation is that obesity confers an increased susceptibility to the development of cardiac disease, while at the same time affording protection against subsequent mortality (termed the obesity paradox). In this review we focus on evidence available from human and animal model studies and summarize the ways in which obesity can influence structure and function of the heart. We also review current hypotheses regarding mechanisms linking obesity and various aspects of cardiac remodeling. There is currently great interest in the role of adipokines, factors secreted from adipose tissue, and their role in the numerous cardiovascular complications of obesity. Here we focus on the role of leptin and the emerging promise of adiponectin as a cardioprotective agent. The challenge of understanding the association between obesity and heart failure is complicated by the multifaceted interplay between various hemodynamic, metabolic, and other physiological factors that ultimately impact the myocardium. Furthermore, the end result of obesity-associated changes in the myocardial structure and function may vary at distinct stages in the progression of remodeling, may depend on the individual pathophysiology of heart failure, and may even remain undetected for decades before clinical manifestation. Here we summarize our current knowledge of this complex yet intriguing topic.

Effect of Coenzyme Q10 and green tea on plasma and liver lipids, platelet aggregation, TBARS production and erythrocyte Na leak in simvastatin treated hypercholesterolmic rats

This study was conducted to investigate the hypocholesterolemic effect of simvastatin (30 mg/kg BW) and antioxidant effect of coenzyme Q10 (CoQ10, 15 mg/kg BW) or green tea (5%) on erythrocyte Na leak, platelet aggregation and TBARS production in hypercholesterolemic rats treated with statin. Food efficiency ratio (FER, ADG/ADFI) was decreased in statin group and increased in green tea group, and the difference between these two groups was significant (p<0.05). Plasma total cholesterol was somewhat increased in all groups with statin compared with control. Plasma triglyceride was decreased in statin group and increased in groups of CoQ10 and green tea, and the difference between groups of statin and green tea was significant (p<0.05). Liver total cholesterol was not different between the control and statin group, but was significantly decreased in the group with green tea compared with other groups (p<0.05). Liver triglyceride was decreased in groups of statin and green tea compared with the control, and the difference between groups of the control and green tea was significant (p<0.05). Platelet aggregation of both the initial slope and the maximum was not significantly different, but the group with green tea tended to be higher in initial slope and lower in the maximum. Intracellular Na of group with green tea was significantly higher than the control or statin group (p<0.05). Na leak in intact cells was significantly decreased in the statin group compared with the control (p<0.05). Na leak in AAPH treated cells was also significantly reduced in the statin group compared with groups of the control and CoQ10 (p<0.05). TBARS production in platelet rich plasma was significantly decreased in the groups with CoQ10 and green tea compared with the control and statin groups (p<0.05). TBARS of liver was significantly decreased in the group with green tea compared with the statin group (p<0.05). In the present study, even a high dose of statin did not show a cholesterol lowering effect, therefore depletion of CoQ10 following statin treatment in rats is not clear. More clinical studies are needed for therapeutic use of CoQ10 as an antioxidant in prevention of degenerative diseases independent of statin therapy.

Effect of angiotensin converting enzyme inhibitor enalapril on body weight and composition in young rats

Obesity is considered a worldwide public health problem showing an increased prevalence in developing countries, with urgent need for new and more efficient drugs and therapies. Enalapril, an angiotensin-I converting enzyme inhibitor (ACEi), is classically used in anti-hypertensive therapies, however, earlier publications have shown that this drug could also have significant impact on body weight in rats as well as in humans, besides reducing blood pressure. The effect of this drug in the white adipose tissue has been neglected for long time, even considering that most components of the renin-angiotensin and kallikrein-kinin system are expressed in this tissue. Furthermore, the adipose tissue is considered today as one of the most important sites for endocrine/inflammatory regulation of appetite and energy output and AngII has been linked to the metabolism in this tissue. Therefore, we analyzed the influence of chronic enalapril treatment in normotensive rats at earlier ages, evaluating body weight, energy homeostasis, lipid profile and serum levels of the hormones leptin and insulin, in the presence of a standard or a palatable hyperlipidic diet regimen for one month. Our results show that enalapril treatment is able to reduce body fat on both diets, without alteration in serum lipid profile. Furthermore, animals receiving enalapril showed reduction in food intake, leptin level and energy intake. In summary, these findings show for the first time that the ACEi enalapril reduces body fat in young normotensive rats and highlights a novel target to treat obesity and associated diseases.

Statin use in Type 2 diabetes mellitus is associated with a delay in starting insulin

AIMS

It has been suggested that HMG Co-A reductase inhibitors ('statins') may reduce the risk of developing Type 2 diabetes mellitus. This study was designed to evaluate whether use of statins would also delay progression to insulin therapy.

METHODS

This was a retrospective cohort study using Saskatchewan Health databases to identify subjects newly started on oral antidiabetic agents from 1991 to 1996.

SUBJECTS

< 30 years of age or with previous lipid-lowering drug use were excluded. Medications known to influence glycaemic control, co-morbidity, and demographic data were collected. Statin exposure was defined as at least 1 year of use. Primary outcome was starting insulin treatment. Multivariate Cox proportional hazards models were used to examine the association between statin use and starting insulin.

RESULTS

The final cohort included 10,996 new users of oral antidiabetic agents, of which 484 (4.4%) used statins. Mean age was 64 years and 55% were male. Mean duration of follow-up was 5.1 years; 11.1% (n = 1221) eventually started insulin treatment. Statin users were no less likely than non-users to start insulin treatment eventually (11.6% vs. 11.1%, P = 0.74). After multivariate adjustment, however, statin use was associated with a 10-month delay before newly treated diabetic subjects needed to start insulin treatment (adjusted hazard ratio 0.74; 95% confidence interval 0.56, 0.97, P = 0.028).

CONCLUSION

The use of statins is associated with a delay in starting insulin treatment in patients with Type 2 diabetes initially treated with oral antidiabetic agents. Whether this relationship exists for patients at high risk of developing diabetes should be examined in a randomized trial.

ACE inhibition may decrease diabetes risk by boosting the impact of bradykinin on adipocytes

The findings of the recent HOPE trial strongly suggest that ACE inhibitor therapy may reduce risk for type 2 diabetes in patients who are non-diabetic at baseline. This finding is readily rationalized by previous evidence that bradykinin, acting via B2 receptors, can potentiate the insulin responsiveness of both adipocytes and muscle fibers; this effect may be mediated by a reduction in the activity of a tyrosine phosphatase that targets the insulin receptor. ACE inhibitors, in turn, increase the availability of bradykinin by suppressing its proteolytic degradation. In light of the fact that the development of insulin resistance in adipocytes is responsible for the excessive free fatty acid flux that gives rise to the diabetic syndrome, a favorable impact of ACE inhibition on adipocyte insulin responsiveness - complemented by a potentiation of the direct action of bradykinin on skeletal muscle - offers a satisfying explanation for the prevention of diabetes observed during ACE inhibitor therapy. Since the population at risk for diabetes is huge and increasing dramatically, the recent development of orally absorbable food-derived peptides with clinically significant ACE inhibitory activity - such as 'Katsuobushi oligopeptides' derived from bonito - may make it more logistically feasible to achieve this protection on a widescale basis, while simultaneously promoting blood pressure control and reducing risk for atherothrombotic disease.