Effect of administration of insulin on streptozotocin-induced diabetic hypertension in rat

The effect of low intensity pulsed ultrasound on dentoalveolar structures during orthodontic force application in diabetic ex-vivo model

OBJECTIVE

This study aimed to investigate the effect of the low intensity pulsed ultrasound (LIPUS) on the dentoalveolar structures during orthodontic force application in ex-vivo model using mandible slice organ culture (MSOC) of diabetic rats.

DESIGN

18 male Wistar rats with a mean weight (275 g) were randomly divided into three main groups: 1) normal rats, 2) Insulin treated diabetic rats, and 3) diabetic rats. Diabetes mellitus (DM) was induced by streptozotocin. Four weeks later, rats were euthanized, mandibles were dissected, divided into 1.5-mm slices creating mandible slice organ cultures (MSOCs). MSOCs were cultured at 37 °C in air with 5 % CO₂. The following day, orthodontic spring delivering a 50-g of force was applied to each slice. In each group, rats were randomly assigned to 2 subgroups; one received 10 min of LIPUS daily and the other was the control. Culture continued for 7 days, and then the sections were prepared for histological and histomorphometric analysis.

RESULTS

For all study groups (Normal, Insulin Treated Diabetic and Diabetic), LIPUS treatment significantly increased the thickness of predentin, cementum, and improved bone remodeling on the tension side and increased odontoblast, sub-odontoblast, and periodontal ligaments cell counts and bone resorption lacunae number on the compression side.

CONCLUSIONS

Application of LIPUS treatment for 10 min daily for a week enhanced bone remodeling and repair of cementum and dentin in normal as well as diabetic MSOCs.

Effect of Lercanidipine on Kidney Microanatomy in Cohen-Rosenthal Diabetic Hypertensive Rats

The study was undertaken to determine the effect of treatment with the dihydropyridine-type calcium antagonist lercanidipine on the renal vasculature in Cohen-Rosenthal diabetic hypertensive rats, a genetic model of hypertension associated with type 2 diabetes mellitus. Eight animals were given a daily oral dose of 3 mg/kg lercanidipine in drinking water for 8 weeks, and 6 control animals received no treatment. The effects on blood pressure, glucose level, and kidney microanatomy were evaluated. Lercanidipine reduced systolic blood pressure and glucose level. In the control group small arteries and glomerular arterioles exhibited wall thickening and luminal narrowing. Lercanidipine administration prevented the changes in small-sized arteries and glomerular arterioles. The glomerular changes observed in the untreated Cohen-Rosenthal diabetic hypertensive rats were not seen in the lercanidipine-treated animals. Lercanidipine also had beneficial effects on the renal vasculature, suggesting that the compound may be considered for treating hypertension associated with diabetes.

Garlic Attenuates Plasma and Kidney ACE-1 and AngII Modulations in Early Streptozotocin-Induced Diabetic Rats: Renal Clearance and Blood Pressure Implications

Raw garlic aqueous extract (GE) has ameliorative actions on the renin-angiotensin system in type-1 diabetes mellitus (DM); however its effects on plasma and kidney angiotensin I converting enzyme type-1 (ACE-1) and angiotensin II (AngII) require further elucidation. This study investigated the effect of GE on plasma and kidney ACE-1 and AngII concentrations and in relation to systemic and renal clearance indicators significant to blood pressure (BP) homeostasis in early streptozotocin- (STZ-) induced type-1 DM. Normal rats (n = 10) received 0.5 mL normal saline (NR/NS), diabetic rats (n = 10) received 0.5 mL NS (DR/NS), and treated diabetic rats (n = 10) received 50 mg/0.1 mL/100 g body weight GE (DR/GE) as daily intraperitoneal injections for 8 weeks. Compared to NR/NS, DR/NS showed a significant increase in plasma ACE-1 and AngII and conversely a decrease in kidney ACE-1 and AngII. These changes were associated with an increase in BP and clearance functions. Alternatively and compared to DR/NS, DR/GE showed normalization or attenuation in plasma and kidney ACE-1 and AngII. These GE induced rectifications were associated with moderation in BP elevation and renal clearance functions. Garlic attenuates modulations in plasma and kidney ACE-1 and AngII, in addition to BP and renal clearance function in type-1 DM.

NO levels in diabetes mellitus: Effects of l-NAME and insulin on LCAT, Na(+)/K(+) ATPase activity and lipid profile

OBJECTIVES

Diabetes mellitus (DM) is a chronic disease and one of the most important health problems. Several factors may be responsible for the complications of diabetes mellitus including alterations in the activities of sodium-potassium adenosine triphosphatase (Na(+)/K(+) ATPase) and lecithin:cholesterol acyltransferase (LCAT) and also levels of nitric oxide (NO). We have investigated the effects of alterations in serum NO levels on activities of erythrocyte membran Na/K ATPase and serum LCAT enzymes.

MATERIALS AND METHODS

The experiments were performed on male rats divided into four groups: group 1, control (standart diet); group 2, diabetic control (single dose of 65mg/kg of streptozotocin (STZ), i.p); group 3, STZ+insulin (8IU/kg/day s.c.); group 4 (STZ+l-NAME 5mg/kg/day orally).

RESULT

Streptozotocin-induced diabetic rats, showed a significant increase in blood glucose and serum cholesterol (C) and triglyceride (TG). Compared to the control group with diabetic group plasma LCAT concentrations and erythrocyte membrane Na(+)/K(+) ATPase were found to be decreased. Activities of Na(+)/K(+) ATPase and serum NO level were decreased with the administration of l-NAME. We observed that insulin was ameliorated in all parameters.

CONCLUSIONS

Serum NO levels is related to erythrocyte membrane Na(+)/K(+) ATPase activity. But serum NO levels did not affect the plasma LCAT activity and serum lipid profiles.

Reversal of diabetic vasculopathy in a rat model of type 1 diabetes by opiorphin-related peptides

Diabetes results in a myriad of vascular complications, often referred to as diabetic vasculopathy, which encompasses both microvascular [erectile dysfunction (ED), retinopathy, neuropathy, and nephropathy] and macrovascular complications (hypertension, coronary heart disease, and myocardial infarction). In diabetic animals and patients with ED, there is decreased opiorphin or opiorphin-related gene expression in corporal tissue. Both opiorphin and the rat homologous peptide sialorphin are found circulating in the plasma. In the present study, we investigated if diabetes induced changes in plasma sialorphin levels and if changes in these levels could modulate the biochemistry and physiology of vascular smooth muscle. We show that circulating sialorphin levels are reduced in a rat model of type I diabetes. Intracorporal injection of plasmids expressing sialorphin into diabetic rats restores sialorphin levels to those seen in the blood of nondiabetic animals and results in both improved erectile function and blood pressure. Sialorphin modulated the ability of C-type natriuretic peptide to relax both corporal and aortic smooth muscle strips and of bradykinin to regulate intracellular calcium levels in both corporal and aortic smooth muscle cells. We have previously shown that expression of genes encoding opiorphins is increased when erectile function is improved. Our findings thus suggest that by affecting circulating levels of opiorphin-related peptides, proper erectile function is not only an indicator but also a modulator of overall vascular health of a man.

Glycaemic control with insulin prevents the reduced renal dopamine D1 receptor expression and function in streptozotocin-induced diabetes

BACKGROUND

It was demonstrated in streptozotocin (STZ)-induced diabetic rats that the D(1) receptor agonist failed to promote sodium excretion as a result of reduced renal D(1) receptor expression and decreased receptor G protein coupling. The present study examined the influence of glycaemic control with insulin on the renal D(1) receptor dysfunction in STZ-induced type 1 diabetes.

METHODS

Renal function, blood pressure, the natriuretic response to 5% volume expansion (VE) and the effects of the D(1) receptor agonist fenoldopam on natriuresis and on Na(+)/K(+)-ATPase activity in renal tubules were evaluated in uninephrectomized and sham-operated Wistar rats treated with STZ and compared with controls and STZ-treated rats made euglycaemic with insulin. D(1) receptor immunohistochemistry and protein abundance by western blot were also determined in all groups.

RESULTS

Treatment of sham and uninephrectomized rats with STZ caused a 4-fold increase in glucose plasma levels compared to controls and euglycaemic diabetic rats. A blunted natriuretic response to VE was observed in both sham and uninephrectomized hyperglycaemic diabetic rats, and this was accompanied by failure of fenoldopam to increase natriuresis and to inhibit renal Na(+)/K(+)-ATPase activity. In contrast, in both sham and uninephrectomized euglycaemic diabetic rats, the natriuretic response to VE, the fenoldopam-induced natriuresis and the accompanied inhibition of Na(+)/K(+)-ATPase activity were similar to those of the corresponding controls. D(1) receptor immunodetection and protein abundance were reduced in hyperglycaemic diabetic rats, but not in euglycaemic diabetic animals.

CONCLUSIONS

We conclude that the renal expression and natriuretic response to D(1) receptor activation is compromised in both sham and uninephrectomized rats with STZ-induced diabetes. These abnormalities were prevented by lowering glucose blood levels with insulin, thus providing evidence for the involvement of hyperglycaemia in the disturbances that underlie the compromised dopamine-sensitive natriuresis and increase of blood pressure in type 1 diabetes.

Gene expression of 11beta-hydroxysteroid dehydrogenase type 1 and type 2 in the kidneys of insulin-dependent diabetic rats

The presence of 11beta-hydroxysteroid dehydrogenase (11beta-HSD) activity in the kidney has been suggested to be important in the regulation of glucocorticoid-induced disorders of electrolyte balance and the control of blood pressure. To assess the possible effect of 11beta-HSD isoforms in diabetes-related hypertension, we measured the mean systolic blood pressure and the 11beta-HSD activity and mRNA levels for both 11beta-HSD1 and 11beta-HSD2 in the kidney of streptozotocin (STZ)-diabetic female rats. Three weeks after injection of STZ (65 mg/kg), the mean systolic blood pressure of diabetic rats was elevated 13.6% above that of normal rats (P<.01). The renal 11beta-HSD2 activity and level of mRNA expression were significantly decreased in diabetic rats (P<.01). However, the treatment of rats with STZ did not decrease the levels of renal 11beta-HSD1 activity and mRNA expression in diabetic rats. Insulin administered subcutaneously to diabetic rats for 2 weeks completely reversed the decrease in renal 11beta-HSD2 activity and gene expression and prevented the elevation in blood pressure in the diabetic rat. These results indicate that alteration of renal 11beta-HSD2 activity and gene expression may be primarily responsible for the changes in blood pressure of STZ-diabetic rats after early treatment with insulin.

Effects of enalapril, losartan, and verapamil on blood pressure and glucose metabolism in the Cohen-Rosenthal diabetic hypertensive rat

We undertook the present study to examine the effect of the angiotensin-converting enzyme inhibitor enalapril, the angiotensin II antagonist losartan, and calcium antagonist verapamil on systolic pressure and spontaneous blood glucose levels in rats from the Cohen-Rosenthal diabetic hypertensive strain. Genetic hypertension and diabetes developed in this strain after crossbreeding of Cohen diabetic and spontaneously hypertensive rats. The new rat strain was fed their usual copper-poor sucrose diet, which is essential for the development of this model, and for 4 weeks received either enalapril, losartan, or verapamil. Systolic pressure was reduced significantly compared with controls in all treated groups. Chronic treatment with enalapril or verapamil, but not with losartan, succeeded in lowering spontaneous blood glucose, indicating improved diabetic control. Data suggest that angiotensin-converting enzyme inhibition by enalapril, but not angiotensin II antagonism by losartan, can improve glucose metabolism in addition to its hypotensive effect in a genetic diabetic hypertensive rat strain. This confirms that the drop in glucose with converting enzyme inhibition is highly dependent on bradykinin accumulation. Data further suggest that calcium channel blockade by verapamil can also improve glucose metabolism. The question remains whether the reduction in glucose by verapamil was a result of inhibition of glucogenesis.