Effect of aminoguanidine on the generation of superoxide anion and nitric oxide by peripheral blood granulocytes of rats with streptozotocin-induced diabetes

doi:10.1016/S0009-8981(98)00130-2

Clinica Chimica Acta

Volume 278, Issue 1, 1 November 1998, Pages 45-53

https://doi.org/10.1016/S0009-8981(98)00130-2 Get rights and content

Abstract

The effect of aminoguanidine (AG) on the production of superoxide anion $O^{−·}_{2}$ and nitric oxide (NO) by peripheral blood granulocytes of rats with streptozotocin-induced diabetes was studied. Induction of diabetes resulted in an increase of $O^{−·}_{2}$ . Generation by both unstimulated and opsonized zymosan-stimulated granulocytes was maximal after 6 weeks and lower after 12 weeks. Treatment with aminoguanidine (1 g/l drinking water) decreased $O^{−·}_{2}$ generation after 6 weeks but not after 12 weeks. NO production by both unstimulated and opsonized zymosan-stimulated granulocytes was elevated in diabetic rats to a comparable extent after 6 and 12 weeks. AG attenuated this increased NO production. These results point to the beneficial effect of AG on oxidative stress in experimental diabetes and suggest an antioxidant effect of AG.

Introduction

The development of vascular complications in diabetes is closely related to the intensity of hyperglycaemia. The mechanisms of this relationship are not fully elucidated but a key role in this respect seems to be played by advanced end products of glycation (AGE) 1, 2. AGE formed in hyperglycaemia contribute to the development of diabetic complications by affecting cellular structure and functions. AGE elevate the levels of intracellular signal transducers such as hormones, cytokines or free radicals. An important role in the development of diabetic vasculopathy is played by the interaction of AGE with AGE-specific cellular receptors (RAGE) localized, e.g., on macrophages, monocytes and endothelial cells 1, 3, 4.

Interaction between AGE and RAGE induces oxidative stress and increased vascular permeability in diabetes, phenomena of key importance for the development of vascular complications in diabetes 5, 6. Under the conditions of hyperglycaemia, the intracellular NADH/NAD ratio is augmented (`pseudohypoxia'). Numerous sequelae of pseudohypoxia include, e.g., activation of free radical production. Moreover, an increased NADH/NAD ratio is a primary mechanism for the increased nitric oxide (NO) production in hyperglycaemia which is believed to be responsible for glomerular hyperfiltration observed in the early stage of development of diabetic nephropathy 7, 8. It has also been observed that AGE inhibit the activity of nitric oxide synthase which would limit the vasodilating effect of NO and therefore decrease the glomerular filtration (GFR) [9].

Recently numerous reports confirm the beneficial effect of aminoguanidine (AG) on the inhibition of diabetic complications [10]. AG therapy was observed to inhibit the inducible NO synthase activity and AGE production but the mechanism of action of this drug is not yet fully understood 11, 12.

The present study aimed to determine free radical generation by peripheral blood granulocytes on streptozotocin-induced diabetes in Wistar rats. The effect of AG therapy on the generation of free radicals was also evaluated.

Section snippets

Materials and methods

The animals used were male Wistar rats, of mean body weight of 256±32 g. The rats were fed standard diet (LSM granulate) and were given water ad libitum.

Diabetes was induced by intraperitoneal injection of streptozotocin (STZ; Sigma; 65 mg/kg body weight) dissolved in 0.1 mol/l sodium citrate, pH 4.5 [13]. Control rats received 1 ml of 0.1 mol/l sodium citrate, pH 4.5. The animals were divided into two×three groups, six rats each: the control group, diabetic animals and diabetic rats receiving

Blood glucose concentration, HbA_1c level and body weight

Glucose concentration in STZ-treated animals was considerably higher than in the control group. AG did not affect significantly the elevated glucose concentration. The level of HbA_1c was significantly increased in the diabetic rats after both 6 and 12 weeks of the experiment. AG did not affect the control of glycaemia in any time point studied. The body weight of diabetic rats was significantly lower as compared with the control group. Inhibition of the body weight gain was similar in the

Discussion

This study employing the model of STZ-induced experimental diabetes demonstrates the occurrence of oxidative stress in diabetes as evidenced by increased generation of the superoxide anion and nitric oxide by peripheral blood granulocytes. Increased production of reactive oxygen and nitrogen species was accompanied by elevated blood glucose concentration and increased level of HbA_1c. These observations are in agreement with the idea of `glucose toxicity' of Ceriello et al. 15, 16 assuming

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This chapter focuses on nitric oxide (NO) electrochemical sensors. Electrochemical (amperometric) detection of NO is the only available technique sensitive enough to detect relevant concentrations of NO in real time and in vivo and suffers minimally from potential interfering species such as nitrite, nitrate, dopamine, ascorbate, and L-arginine. As NO electrodes can be made on the micro- and nano-scale, these techniques have the advantage of being able to measure NO concentrations in living systems without any significant effects from electrode insertion. The first described electrochemical NO sensor was based on a classical Clark electrode design, where NO was directly oxidized on the working electrode surface. Surface modified NO sensors incorporate an electrode surface that is modified or treated to increase the selectivity of the sensor for NO and promote catalytic oxidation of NO. In most applications detection limit, sensitivity, selectivity and response time are usually the most important requirements. The sensitivity of an NO sensor is directly proportional to the electrode size and surface status, where an electrode with a small surface area will generally have a lower sensitivity compared to the one with a larger surface area. Selectivity is controlled by the voltage applied between the working and reference electrode (poise voltage), and the selective membrane used for coating the sensor. The response time depends on the electrode and the electronics being used to read out the current. Currently NO electrochemical sensors provide the only means to measure NO continuously, accurately and directly within living tissue without significant damage.
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This section will point out several examples in which NO microsensors were used to determine the biological effects of NO (Tristani‐Firouzi et al., 1998). NO release, NO consumption, and levels of applied NO have been measured in a variety of biological systems, including eyes (Akeo et al., 2000; Amaki et al., 2001; Millar, 2003; Sekaran et al., 2005), gastrointestinal tract (Asanuma et al., 2005; Iijima et al., 2002; Stefano et al., 2004), brain tissue (Buerk et al., 2003; Cherian et al., 2000; Fabre et al., 1997; Ferreira et al., 2005; Meulemans, 2002; Rocchitta et al., 2004), kidney and kidney tubule fluid (Arregui et al., 2004; Levine et al., 2001, 2004; Levine and Iacovitti, 2003, 2006; Saitoand and Miyagawa, 2000; Thorup et al., 1998), rat and guinea pig isolated and intact hearts (Fujita et al., 1998; Novalija et al., 1999), rat spinal cord (Schulte and Millar, 2003), human monocyte cells (Stefano et al., 1999), human endothelial cells (Stefano et al., 2000), mitochondria (Beltran et al., 2002; Shiva et al., 2001), rat penis corpus cavernosum (Mas et al., 2002), granulocytes (Kedziora‐Kornatowska et al., 1998), invertebrate ganglia and immunocytes (Stefano et al., 2002), choroidal endothelial cells (Uhlmann et al., 2001), cancer cells (Bal‐Price et al., 2006; Kashiwagi et al., 2005; Tsatmali et al., 2000), peripheral blood (Rysz et al., 1997), human blood (Rievaj et al., 2004), human leukocytes (Larfars et al., 1999), platelets (De La Cruz et al., 2003; Freedman et al., 1997; Kasuya et al., 2002), ears (Jiang et al., 2004; Shi et al., 2002), plants (Grande et al., 2004; Sakihama et al., 2002; Yamasaki et al., 1999; Yamasaki and Sakihama, 2000), and pteropod mollusks (Moroz et al., 2000). Levine and colleagues first reported on the real‐time profiling of kidney tubular fluid NO concentration in vivo (Levine et al., 2001, 2004; Levine and Iacovitti, 2006).
Since nitric oxide (NO) was identified as the endothelial‐derived relaxing factor in the late 1980s, many approaches have attempted to provide an adequate means for measuring physiological levels of NO. Although several techniques have been successful in achieving this aim, the electrochemical method has proved the only technique that can reliably measure physiological levels of NO in vitro, in vivo, and in real time.
We describe here the development of electrochemical sensors for NO, including the fabrication of sensors, the detection principle, calibration, detection limits, selectivity, and response time. Furthermore, we look at the many experimental applications where NO selective electrodes have been successfully used.
Aminoguanidine renders inducible nitric oxide synthase knockout mice more susceptible to Salmonella typhimurium infection
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Aminoguanidine (AG), a nitric oxide synthase (NOS) inhibitor, has been widely used to study the role of inducible NOS (iNOS) in host defense against infections caused by various pathogens including Salmonella typhimurium. iNOS has been reported to play an important role in host defense against S. typhimurium infection both in vitro and in vivo. In this report we show those AG treatment lead to weight loss in both wild-type and iNOS knockout mice, and rendered them more susceptible to Salmonella infection. These results suggest that AG may have side effects other than the inhibition of iNOS, and that data obtained from studies using AG should be interpreted with caution.
Protective effect of aminoguanidine against paraquat-induced oxidative stress in the lung of mice
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The effect of aminoguanidine (AG) against toxicity of paraquat (PQ), an oxidative-stress inducing substance, in mice was investigated. A single dose of PQ (50 mg/kg, i.p.) induced lung-toxicity, manifested by significant decrease of the activity of angiotensin converting enzyme (ACE) in lung tissue indicating pulmonary capillary endothelial cell damage. Lung toxicity was further evidenced by significant decrease of total sulfhydryl (–SH) content and significant increase in lipid peroxidation measured as malondialdehyde (MDA) in lung tissues. Oral pretreatment of mice with AG (50 mg/kg) in drinking water, starting 5 days before PQ injection and continuing during the experimental period, ameliorated the lung toxicity induced by PQ. This was evidenced by a significant increase in the levels of ACE activity, a significant decrease in lung MDA content and a significant increase in the total sulfhydryl content 24 h after PQ administration. Moreover, pretreatment of mice with AG leads to an increase of the LD₅₀ value of paraquat. These results indicate that AG is an efficient cytoprotective agent against PQ-induced lung toxicity.
Effects of aminoguanidine and desferrioxamine on some vascular and biochemical changes associated with streptozotocin-induced hyperglycaemia in rats
2001, Pharmacological Research
The effects of aminoguanidine (AG; 100 mgkg⁻¹) and desferrioxamine (DFO; 50 mgkg⁻¹) on some vascular and biochemical changes associated with streptozotocin (STZ; 65 mgkg⁻¹; i.p.)-induced hyperglycaemia were investigated in rats. Both AG and DFO were administered i.p., once daily, for 14 consecutive days to normal and hyperglycaemic animals. The responsiveness of the isolated aortic rings to phenylephrine (PE) was tested. In addition, biochemical markers for oxidative stress such as plasma levels of lipid peroxides and total thiols, as well as the activities of erythrocytic superoxide dismutase (SOD) and whole blood glutathione peroxidase (GSH-Px) were assessed. Results of the present study indicated that induction of hyperglycaemia was associated with increased aortic ring responsiveness to PE, loss in body weight, increase in urine volume, elevation of plasma total thiols and lipid peroxide levels and elevated SOD and GSH-Px enzymatic activities. Treatment of normal rats with AG reduced the response of their aortae to PE. Furthermore, a profound increase in body weight without any significant change in the measured biochemical parameters was observed. In hyperglycaemic animals, AG tended to normalize the enhanced aortic response to PE and modulated STZ-induced biochemical changes without affecting the elevated plasma glucose level. Treatment of normal rats with DFO reduced the response of their aortae to PE and decreased their body weight without altering any of the chosen biochemical parameters. In hyperglycaemic animals, DFO attenuated the responsiveness of their aortae to PE and at the same time, did not affect the loss in body weight and the elevation of plasma glucose level observed in the hyperglycaemic group. Additionally, DFO normalized the elevated plasma level of total thiols and exerted a modulatory influence on the enhanced activities of SOD and GSH-Px as well as on the increased levels of lipid peroxides. Our data lend further credence for the contribution of oxidative stress in the vascular and biochemical changes associated with STZ-induced hyperglycaemia. It is also apparent that advanced glycosylation end products and nitric oxide might be involved. Until clinical studies prove the efficacy and safety of these drugs, specific agents which could scavenge free radicals and block protein glycosylation seem beneficial as a helpful adjunct to the therapy of diabetes.

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Effect of aminoguanidine on the generation of superoxide anion and nitric oxide by peripheral blood granulocytes of rats with streptozotocin-induced diabetes

Abstract

Introduction

Section snippets

Materials and methods

Blood glucose concentration, HbA1c level and body weight

Discussion

Am J Kidney Dis

Kidney Int

Kidney Int

U Surg Res

Immunol Lett

Receptor-mediated endothelial cell dysfunction in diabetic vasculopathy. Soluble receptor for advanced glycation end products blocks hyperpermeability in diabetic rats

J Clin Invest

Glycation and diabetic complications

Diabetes

Role of Amadori-modified nonenzymatically glycated serum proteins in the pathogenesis of diabetic nephropathy

Am U Soc Nephrol

Toxicity of glucose: is AGE the answer?

Nephrol Dial Transplant

The relative roles of advanced glycation, oxidation and aldose reductase inhibition in the development of experimental diabetic nephropathy in the Sprague–Dawley rat

Diabetologia

Nitric oxide: physiology, pathophysiology and pharmacology

Pharmacol Rev

Advanced glycosylation products quench nitric oxide and mediated defective endothelium-dependent vasodilation in experimental diabetes

J Clin Inv

Aminoguanidine inhibits the development of accelerated diabetic retinopathy in the spontaneous hypertensive rat

Diabetologia

Aminoguanidine, a novel inhibitor of nitric oxide formation, prevents diabetic vascular dysfunction

Diabetes

Blood glucose concentration, HbA_1c level and body weight