Aminoguanidine Research Articles

Inducible nitric oxide synthase inhibitor aminoguanidine, differently affects Morris water maze tasks of ovariectomized and naïve female rats

The role of ovarian hormones, nitric oxide, and their interaction on learning and memory has been widely investigated. The objective of present study was to investigate different effects of chronic administration of inducible nitric oxide synthase inhibitor, aminoguanidine (AM) on learning and memory of ovariectomized (OVX) and naïve (Sham) female rats. Thirty-two rats were divided into four groups: 1) Sham, 2) OVX, 3) Sham-AM and 4) OVX-AM. The animals of Sham-AM and OVX-AM chronically received 100 mg/kg/day of aminoguanidine during 8 weeks before 5 test days. The animals in Sham and OVX groups received 1 ml/kg saline instead of aminoguanidine. The animals were tested in Morris water maze and the escape latency and traveled path to reach the platform were compared between groups. On the fifth day, the platform was removed, and the animals were allowed to swim for 60 s ( prob trial). The time spent in the target quadrant (Q1) was compared between groups.Results showed that the escape latency and traveled path in OVX group were significantly higher than in the Sham group (p<0.01). Both escape latency and traveled path in the Sham-AM group was significantly higher than in the Sham group (p<0.01) however, there was no significant difference between OVX-AM and OVX groups.The time spent by the animals of OVX group in the target quadrant (Q1) during the probe trial was significantly lower than that in the Sham group (p<0.01). The animals of the Sham-AM group spent shorter times in the target quadrant in comparison with the Sham group (p<0.01). There was no significant difference between the OVX and OVX-AM groups in the time spent in tarthe get quadrant. It is concluded that the effect of aminoguanidine on learning and memory is different in the presence or absence of ovarian hormones but it needs further investigation.

Aminoguanidine normalizes ET-1-induced aortic contraction in type 2 diabetic Otsuka Long–Evans Tokushima Fatty (OLETF) rats by suppressing Jab1-mediated increase in ETA-receptor expression

Circulating levels of endothelin (ET)-1 are increased in the diabetic state, as is endogenous ETA-receptor-mediated vasoconstriction. However, the responsible mechanisms remain unknown. We hypothesized that ET-1-induced vasoconstriction is augmented in type 2 diabetes with hyperglycemia through an increment in advanced glycation end-products (AGEs). So, we investigated whether treatment with aminoguanidine (AG), an inhibitor of AGEs, would normalize the ET-1-induced contraction induced by ET-1 in strips of thoracic aortas isolated from OLETF rats at the chronic stage of diabetes. In such aortas (vs. those from age-matched genetic control LETO rats): (1) the ET-1-induced contraction was enhanced, (2) the levels of HIF1α/ECE1/plasma ET-1 and plasma CML-AGEs were increased, (3) the ET-1-stimulated ERK phosphorylation mediated by ETA-R was increased, (4) the expression level of Jab1-modified ETA-R protein was reduced, and (5) the expression level of O-GlcNAcylated ETA-R protein was increased. Aortas isolated from such OLETF rats that had been treated with AG (50mg/kg/day for 10 weeks) exhibited reduced ET-1-induced contraction, suppressed ET-1-stimulated ERK phosphorylation accompanied by down-regulation of ETA-R, and increased modification of ETA-R by Jab1. Such AG-treated rats exhibited normalized plasma ET-1 and CML-AGE levels, and their aortas exhibited decreased HIF1α/ECE1 expression. However, such AG treatment did not alter the elevated levels of plasma glucose or insulin, or systolic blood pressure seen in OLETF rats. These data from the OLETF model suggest that within the timescale studied here, AG normalizes ET-1-induced aortic contraction by suppressing ETA-R/ERK activities and/or by normalizing the imbalance between Jab1 and O-GlcNAc in type 2 diabetes.

COX-2 and survivin reduction may play a role in berberine-induced apoptosis in human ductal breast epithelial tumor cell line

Berberine is an isoquinoline alkaloid that has several pharmacological effects such as antiinflammatory, antimicrobial, apoptosis-inducing and anticancer effects. It has been illustrated that the antiinflammatory effect is mediated by suppressing the nuclear factor-kappa B (NF-κB) that activates expression of some antiinflammatory and antiapoptotic proteins including cyclooxygenase-2(COX-2), inducible nitric oxide synthase (iNOS) and survivin; therefore, berberine may induce apoptosis by reducing antiinflammatory and antiapoptotic agents, which suggest the relationship between antiinflammatory and apoptosis pathways. For further illustration of the mechanism of berberine action, the human ductal breast epithelial tumor cell line (T47D cell line) was treated with different concentrations of berberine (25-100 μM/ml). Berberine in 50 μM/ml had the most reducing effect on cell viability and inducing of apoptosis. The level of COX-2, iNOS and survivin proteins decreased in berberine-treated cells; however, treatment of the cells with aspirin and aminoguanidine (AG), COX-2 and iNOS inhibitors, respectively, showed that despite the cell growth-reducing effect of aspirin, AG did not have a significant effect on cell viability. On the other hand, with the attention to reduction in survivin protein level in berberine-treated cells, the results suggest that the apoptotic effect of berberine may be mediated by reduction in both of the COX-2 and survivin in T47D cell line, while the iNOS does not play any effective role in berberine-induced apoptosis.

Aminoguanidine and curcumin attenuated tumor necrosis factor (TNF)-α-induced oxidative stress, colitis and hepatotoxicity in mice

The up regulation of gut mucosal cytokines such as tumor necrosis factor (TNF)-α and oxidative stress have been related to inflammatory bowel diseases (IBD) such as ulcerative colitis (UC) and Crohn's disease (CD). This study investigated an immune-mediated model of colitis. TNF-α injected intraperitonally to mice induced a dose-dependent recruitment of neutrophils into abdominal mesentery. The leukocytes influx induced by TNF-α (10 μg kg − 1 body weight) increased by 3 fold liver and colon damage scores. TNF-α-colitis was characterized by hemorrhagic edemas and crypt abscesses massively infiltrated by inflammatory cells, namely neutrophils. Moreover, TNF-α-toxicity resulted in liver steatosis and foci of necrosis infiltrated by Kupffer cells and neutrophils in parenchyma and around the centrilobular veins. The involvement of oxidative stress was evaluated using aminoguanidine (AG) as selective inhibitor of inducible NO synthase (iNOS) and curcumin (Cur), the polyphenolic antioxidant of turmeric ( Curcuma longa L.). TNF-α-toxicity led to significant increase in myeloperoxidase (MPO, an index of neutrophils infiltration), nitrites (stable nitric oxide metabolites) and malondialdehyde (MDA, a marker of lipid peroxides) levels and cell apoptosis in liver and colon. AG and Cur treatments significantly attenuated the hallmarks of oxidative stress, neutrophils influx and ROS-related cellular and histological damages, in TNF-α-treated mice. Taken together, our results provide insights into the role of phagocytes-derived oxidants in TNF-α-colitis in mice. Cur and AG, by inhibiting neutrophils priming and iNOsynthase could be effective against oxidative bowel damages induced in IBD by imbalanced gut immune response.

Controversial behavior of aminoguanidine in the presence of either reducing sugars or soluble glycated bovine serum albumin

The elucidation of the controversial inhibitory effect of aminoguanidine (AG) on the cross-linking and fluorescent advanced glycation end products (AGEs) formation during long-term in vitro glycation of type I collagen with 250 mM reducing sugars or 0.5 mg/ml soluble glycated bovine serum albumin (AGE-BSA) was researched. Chromatographic and SDS–PAGE analyses revealed the formation of aggregates during collagen glycation. AG at all concentrations (5–80 mM) prevented the cross-linking of collagen peptides with monosaccharides but an increase in fluorescence with a maximum value at 10 mM AG was noticed. In the presence of AGE-BSA, AG prevented the cross-linking process and decreased the fluorescence levels in a concentration-dependent manner. Our results suggest that AG is an efficient inhibitor of collagen cross-linking and the highest increase in fluorescence due to reducing sugars and AG can be explained by the competition between guanidine group of AG and arginine residues of some protein-bound dideoxyosones, which could form fluorescent compounds.

A facile synthesis of imino-protected cyclic guanidine derivatives from diamines

Abstract A convenient one-step synthesis of five-membered or six-membered imino-protected cyclic guanidine via an intramolecular ring-closure reaction of alkyl diamine ( 2a – 2g ) with 1, 3-diamino-protected methylisothiourea ( 1a and 1b ) was established and investigated. Amino guanidine such as 3-(2-aminoethyl)-1, 2-dibenzyloxycarbonylguanidine ( 4a ) has been proved to be the intermediate of the reaction via utilizing mono-protected diamine as starting material. The intramolecular ring closure of 4a results in 2-benzyloxycarbonyliminoimidazolidine ( 3a ). This new one-step synthesis has advantages of simple condition, easy workup procedure and reasonable yield.

The relative efficacy of aminoguanidine and pentoxifylline in modulating endotoxin-induced cardiac stress

This study investigates the effect of aminoguanidine (AG), a selective inducible nitric oxide synthase (iNOS) inhibitor, and pentoxifylline (PTX), a tumour necrosis factor-alpha (TNF-α) inhibitor, on lipopolysaccharide (LPS)-induced cardiac stress. Rats were divided into four groups: group I served as a control, group II (LPS) received a single intraperitoneal injection of LPS (10 mg·kg(-1) ), group III (LPS+AG) and group IV (LPS+PTX) were injected with either AG (100 mg·kg(-1) ) or PTX (150 mg·kg(-1) ) intraperitoneally 10 days prior to LPS administration. Normalization of cardiac levels of nitrite/nitrate (NO(X) ), malondialdehyde (MDA), glutathione (GSH), heme oxygenase-1 (HO-1), glutathione peroxidase (GPx) and Na(+) , K(+) -ATPase activities was evident in the AG group. Both AG and PTX decreased the elevated serum TNF-α levels, the activities of lactate dehydrogenase (LDH), creatine kinase (CK) and cardiac myeloperoxidase (MPO). The levels of adenosine triphosphate (ATP), adenosine diphosphate (ADP) and phosphocreatine (PCr) were enhanced following AG and PTX pretreatments. Calcium (Ca(2+) ) levels were altered, and the histopathological observations supported the described results. Conclusively, the study highlights the cardioprotective potential of AG and PTX with superior results from AG. These findings reveal the relative contribution of nitric oxide and TNF-α to oxidative stress and energy failure during endotoxemia.

Aminoguanidine, a Selective Nitric Oxide Synthase Inhibitor, Attenuates Cyclophosphamide-Induced Renal Damage by Inhibiting Protein Nitration and Poly(ADP-Ribose) Polymerase Activation

Background: Cyclophosphamide (CP) is an antineoplastic agent that is used for the treatment of many neoplastic diseases. Renal damage is one of the dose-limiting side effects of CP. Recent studies show that nitrosative stress plays an important role in CP-induced renal damage. Aim: The purpose of our study was to investigate whether aminoguanidine (AG), a selective inducible nitric oxide synthase inhibitor, protects against CP-induced nitrosative stress and renal damage. Method: Renal damage was induced in rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 h before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 h after the administration of CP or saline. Pretreatment with AG prevented CP-induced nitration of protein tyrosine and poly(ADP-ribose) polymerase (PARP) activation. Result: Pretreatment with AG attenuated CP-induced renal damage. The present study demonstrates that AG is effective in preventing CP-induced renal damage and also that the protective effect is from its ability to inhibit nitric oxide-induced protein nitration and PARP activation. Conclusion: The present study shows that AG can prevent CP-induced renal damage by inhibiting protein tyrosine nitration and PARP activation. Thus, a more efficient and comfortable therapy can be achieved for patients in need of CP treatment. AG appears to be a promising drug for the prevention of nephrotoxicity of CP.

Role of NO and ERK signaling pathways in spinal cord in naloxone-induced withdrawal response in morphine-dependent rats

Objective To investigate the role of NO and extracellular signal-regulated kinase (ERK) signaling pathways in the spinal cord in naloxone-induced withdrawal response in morphine-dependent rats.Methods Ninety male adult SD rats weighing 200-250 g in which IT catheters were successfully implanted without complication were randomly divided into 9 groups (n ＝ 10 each):group control (group C); group morphine dependence (group MD); group morphine withdrawal (group MW); group N(G)-nitro-L-arginine methyl ester (eNOS inhibitor) (L-NAME group) ; group 7-nitroindazole (nNOS inhibitor) (group 7-Ni) ; group aminoguanidine(iNOS inhibitor) (group AG); group U0126 (ERK signaling pathway blocker); group cremophor (solvent for 7-Ni) and group DMSO (solvent for U0126).Morphine dependence was induced by increasing doses of subcutaneous morphine for 6 days.The initial dose of morphine was 10 mg/kg twice a day and was increased by 10 mg/kg twice every other day until 50 mg/kg on the 6th day in groups MD,MW,L-NAME,7-Ni,AG,U0126,cremophor and DMSO.Morphine withdrawal response was induced by intraperitoneal (IP) naloxone 4 mg/kg at 4 h after last morphine administration in groups MW,L-NAME,7-Ni,AG,U0126,cremophor and DMSO.L-NAME 400 μg,7-Ni 400 μ g,AG 400 μg,U0126 150 μg,cremopher 10 μl and DMSO 10 μl were administered IT at 30 min before naloxone administration in groups L-NAME,7-Ni,AG,U0126,cremophor and DMSO respectively.Morphine withdrawal response (0 ＝ no withdrawal response,3 ＝ severe response) and touch evoked agitation (0 ＝ no agitation,2 ＝ severe agitation) were observed and scored during 1 h after naloxone administration.The animals were then sacrificed and the spinal cord was removed for determination of the expression of iNOS,nNOS and phosphor-ERK (p-ERK) by immunohisto-chemistry and Western blot.Results Morphine withdrawal significantly increased withdrawal response score and touch evoked agitation score in group MW as comparedwith group MD.L-NAME,7-Ni,AG and U0126 pretreatment significantly attenuated naloxone-induced increase in withdrawal response score and touch evoked agitation score in groups L-NAME,7-Ni,AG and U0126 as compared with group MW.Morphine withdrawal significantly up-regulated the nNOS and iNOS expression in group MW compared with groups C and MD.L-NAME,7-Ni and AG pretreatment significantly down-regulated p-ERK expression in groups L-NAME,7-Ni and AG as compared with group MW.Conclusion The interaction between NO and ERK signaling pathways may be involved in morphine withdrawal response in morphine-dependent rats. Key words: Nitric oxide; Extracellular signal-regulated MAP kinases; Spinal cord; Morphine dependence; Substance withdrawal syndrome

In vitro studies on efficacy and toxicity of aminoguanidine

In vitro studies on efficacy and toxicity of aminoguanidine

AGE formation blockade with aminoguanidine does not ameliorate chronic allograft nephropathy

AimsAdvanced glycation end products (AGEs) are produced by glycoxidation and lipid peroxidation. AGEs induce oxidative stress and inflammation, and accumulate in tubular cells after kidney transplantation. We hypothesize that the AGE formation blocker aminoguanidine (AG) reduces AGE formation and improves renal transplant function. Main methodsFisher 344 kidneys were orthotopically transplanted into Lewis recipients. Recipients were treated with AG (100mg/kg/day), candesartan (CAND; 5mg/kg/day), or vehicle (VEH) for 24weeks. The major non-cross linking AGE Nε-carboxymethyllysine (CML) was measured post-transplantation with gas chromatography-tandem mass spectrometry or immunohistochemistry. As a marker of systemic lipid peroxidation 8-isoprostane was measured by ELISA. We determined intra-arterial blood pressure, heart weight/body weight ratio, size of cardiomyocytes and cardiac hypertrophy as assessed by echocardiography. For biochemical evaluation of cardiac and renal fibrosis we measured hydroxyproline content. Key findingsAG significantly reduced serum CML and 8-isoprostane, but did not reduce signs of chronic allograft nephropathy (CAN) or blood pressure. AG did not alter tubular AGE accumulation. AG reduced heart weight/body weight ratio (AG: 2.7±0.1g/kg; CAND: 2.2±0.1, VEH: 3.0±0.4g/kg), size of cardiomyocytes (P<0.05) and showed a tendency to reduce cardiac hypertrophy (wall volume average radial AG 7.072±0.83cm3 vs. CAND 6.841±0.66cm3 vs. VEH 7.839±0.74cm3). SignificanceDespite effective reduction of serum CML and 8-isoprostane, AG did not ameliorate CAN or reduce renal AGE accumulation. On the other hand AG reduced cardiac size suggesting a supportive cardio-protective action which is blood pressure independent.

Aminoguanidine and N-acetyl-cysteine supress oxidative and nitrosative stress in EAE rat brains

Experimental autoimmune encephalomyelitis (EAE) is a well-established animal model of human multiple sclerosis (MS). We have evaluated the role of oxidative and nitrosative stress, as the causal factors in the development of EAE, responsible for the damage of cardinal cellular components, such as lipids, proteins and nucleic acids, resulting in demyelination, axonal damage, and neuronal death. EAE was induced in female Sprague-Dawley rats, 3 months old (300 ± 20 g), by immunization with myelin basic protein in combination with Complete Freund's adjuvant (CFA). The animals were divided into seven groups: control, EAE, CFA, EAE + aminoguanidine (AG), AG, EAE + N-acetyl-l-cysteine (NAC) and NAC. The animals were sacrificed 15 days after EAE induction, and the levels of nitrosative and oxidative stress were determined in 10% homogenate of the whole encephalitic mass. In EAE rats, brain NO production and MDA level were significantly increased (P < 0.001) compared to the control values, whereas AG and NAC treatment decreased both parameters in EAE rats compared to EAE group (P < 0.001). Glutathione (GSH) was reduced (P < 0.001) in EAE rats in comparison with the control and CFA groups, but increased in EAE + AG and EAE + NAC group compared to the EAE group (P < 0.01). Superoxide dismutase (SOD) activity was significantly decreased (P < 0.001) in the EAE group compared to all other experimental groups. The clinical expression of EAE was significantly decreased (P < 0.05) in the EAE groups treated with AG and NAC compared to EAE rats, during disease development.The obtained results prove an important role of oxidative and nitrosative stress in the pathogenesis of EAE, whereas AG and NAC protective effects offer new possibilities for a modified combined approach in MS therapy.

The protective mechanism for the blood-brain barrier induced by aminoguanidine in surgical brain injury in rats.

This study was performed to investigate the mechanism of blood-brain barrier (BBB) permeability change, which was induced by aminoguanidine (AG) after surgical brain injury (SBI) in rats. Compared to control group, AG (150 mg/kg, i.p.) significantly reduced Evans blue extravasation into brain tissue at 24 h after surgical resection, it also induced a 32% decrease of malondialdehyde (MDA) values and a 1.1-fold increase of the glutathione (GSH) levels at 12 h after injury. The expression of inducible nitric oxide synthase (iNOS) reached the peak value at 24 h after SBI, which was significantly attenuated after AG treatment. In addition, ZO-1 protein was up-regulated by AG (150 mg/kg) treatment at 24 h after SBI. Our results indicated that AG could protect the BBB after SBI, which could be correlated with antioxidative property, the down-regulation of iNOS and up-regulation of tight junction protein expression.

Effect of aminoguanidine on caspase-3 expression in rat retina after ischemia-reperfusion injury.

To investigate the effect of aminoguanidine (AG) on the expression of caspase-3 in rat retina after ischemia- reperfusion injury. The rats were anesthetized with 30mg/kg sodium pentobarbital introperitoneal(ip) injections. After topical application of 10g/L dicaine, the anterior chamber was punctured with a 5-gauge needle connected to a bottle containing normal saline. Intraocular pressure was raised to 100 mmHg by elevating the saline container. The infusion needle was removed from the anterior chamber 60 minutes later. Reperfusion of the retinal vasculature was confirmed by fundus examination. AG 100mg/kg was ip injected in drug group. The rats were then euthanatized at 6, 24, and 72 hours after reperfusion, and their eyes were enucleated for immunohistochemistry. No specific staining was detected by using the caspase-3 antibody in the retina of control group. In ischemia group, the protein of caspase-3 was over-expressed at 6 hours and relieved at 24 hours and 72 hours, while with drug treatment, the expression of protein of caspase-3 was decreased at each time point. AG provides retinal protection against ischemia-reperfusion injury in rat retina, probably through an inducible NOS-dependent mechanism.

Effects of L-arginine and aminoguanidine on ischemia-reperfusion injury following rat lung transplantation

Objective To investigate the effects of L-arginine (L-Arg) and aminoguanidine on ischemia-reperfusion injury following rat lung transplantation. Methods The models of rats lung transplantation were established and 4 groups ( n = 6 each) were randomly set up: group A ( normal control group)and treated groups B, C and D. In these groups, different medicines (NS, group A; L-Arg, group B;aminoguanidine, group C; L-Arg and aminoguanidine, group D) were intraperitoneally administered to the recipient rats before reperfusion. After reperfusion for 2 h, the lung graft was harvested for measurements of lung wet/dry ratio ( W/D ) , myeloperoxidase ( MPO ) , malondialdehyde ( MDA ) , superoxide dismutase (SOD) , endothelial nitric oxide synthase (eNOS) , inducible nitric oxide synthase (iNOS). The contents of plasma nitric oxide (NO) were determined. The pathological changes in the lung grafts were observed.Results After reperfusion for 2 h, W/D (5. 10 ±0.21), MPO (1.74 ±0.26) U/g, MDA (20.87 ±2. 90) μmol/g in group B were significantly lower [W/D (5. 74 ± 0. 14), MPO (2. 36 ± 0. 32) U/g,MDA (31. 33 ±3.46) μmol/g] (P ＜ 0. 05), and the levels of SOD (424. 29 ± 27. 86) U/mg protein,NO (175. 12 ± 17. 40) μmol/L, iNOS (3. 62 ±0. 26) U/mg protein and eNOS (5. 36 ±0. 28) U/mg protein were significantly higher than in group A [SOD (268.01 ±26.06) U/mg protein, NO (98.29 ±6.95) μmol/L, iNOS (2.53 ±0.22) U/mg protein and eNOS (3. 57 ±0.40) U/mg protein] (P＜0. 05). The contents of NO (84. 13 ±5. 18) μmol/L and iNOS (1. 81 ±0. 09) U/mg protein in group C were significantly lower than in group A (P ＜ 0. 05). W/D (4. 79 ± 0. 19) , MPO (1. 24 ± 0. 13 ) U/g,MDA (14. 60 ±4. 14) μmol/g, iNOS (1. 99 ±0. 17) U/mg protein were significantly lower than in group A (P ＜0. 05) , and SOD (493. 75 ±24. 95) , NO (149. 61 ± 10. 70) μmol/L and eNOS (5. 50 ±0. 27)U/mg protein in group D were significantly higher than in group A (P＜0. 05). W/D, MPO, MDA, NO and iNOS in group D were significantly reduced as compared with group B (P ＜ 0. 05 ) , and SOD was significantly increased in group B ( P ＜ 0. 05 ) . The pathological examination revealed that the inflammatory cell infiltration in group D was the mildest, followed by groups B, A and C. Conclusion The L-Arg could alleviate the lung ischemia-reperfusion injury after transplantation, the combined used of L-Arg and aminoguanidine could obtain better effects than L-Arg used alone. The aminoguanidine used alone could not alleviate ischemia-reperfusion injury after transplantation. Key words: Lung transplantation; Reperfusion injury; Nitric oxide synthase; Arginine; Aminoguanidine

Effect of Aminoguanidine in Sperm DNA Fragmentation In Varicocelized Rats: Role of Nitric Oxide

The sperm of infertile men with varicocele exhibit markedly high DNA damage that appears to be related to high oxidative stress (OS). Aminoguanidine (AG) is a specific inhibitor of the nitric oxide synthase (NOS) isoforms iNOS and an antioxidant, the effects of which decrease NO and peroxynitrite production. The aim of this study was to determine the effects of AG on sperm chromatin in varicocelized rats. Thirty male Wistar rats were divided into 5 groups: control, sham, varicocele, and AG and placebo-treated groups. At 10 weeks after varicocele induction, sperm chromatin was evaluated in all groups, except in the treated groups. The treated groups received intraperitoneal injections of 50 mg/kg AG or placebo daily for 10 weeks and then were killed for chromatin assessment. Sperm chromatin was evaluated by aniline blue, acridine orange, toluidine blue, and chromomycin A(3) staining. The results of the 4 above tests were significantly increased between varicocele and control (and sham) groups (P < .05). The findings of this study suggest that AG improves sperm DNA fragmentation that is associated with infertility in varicocelized rats, and treatment with AG can reduce the damage to sperm DNA.

Effects of Needle-knife Therapy on iNOS Activity and NO Content in Skeletal Muscles in the L 3 Transverse Process Syndrome Model Rat

To study on relationship of inducible nitric oxide synthase (iNOS) activity and nitric oxide (NO) content in the injured local soft tissue with injured degrees of the soft tissue in the third lumbar vertebrae (L3) transverse process syndrome model rat and to observe the effect of needle-knife therapy. One hundred and sixty male SD rats were randomly divided into normal group, model group, aminoguanidine (AG) group, needle-knife group, 40 rats in each group. The L3 transverse process syndrome rat model was established, and after treatment of needle-knife and AG iNOS activities and NO contents and histomorpholocal changes in the soft tissues around L3 transverse process on 1, 3, 7 and 14 days were observed in the groups. Compared with the normal group, iNOS activity and NO content in the model group were significantly increased (P < 0.01); Compared with the model group, iNOS activities and NO contents were significantly decreased in both the needle-knife group and the AG group (both P < 0.01); And both iNOS activities and NO contents were identical with both local inflammation response and injured degrees of the injured tissue in the groups. Needle-knife therapy can significantly inhibit generation of NO, alleviate inflammatory response and injured degree of the injured soft tissue, improve microcirculation, prevent formation of pathological scar tissue, and promote repair of the chronic soft tissue injury.

Intraperitoneal aminoguanidine improves sciatic nerve ischemia-reperfusion injury in male sprague-dawley rats.

The present work was designed to investigate the potential protective effects of post-ischemic treatment with aminoguanidine (AG) on sciatic nerve ischemia/reperfusion (I/R) injury in rat. Seventy-two rats were divided into 12 groups (n = 6). We used ischemia model in these groups by occluding the right common iliac and femoral arteries for 3 h with a silk suture 6-0 using slipknot technique. Treatment groups (2, 4, 6, 8, 10, and 12) received 150 mg/kg AG intraperitoneally 24 h after induction of ischemia. After certain time intervals of reperfusion (2, 4, 7, 14, and 28 days), the function of the hind limb was assessed using behavioral scores based on gait, racing reflex, toe spread, pinch sensitivity, paw position, and grasp. After euthanasia, sciatic nerves were removed at the end of reperfusion times and sections were cut at 5 μm, then were stained for light microscopy studies and graded for ischemic fiber degeneration (IFD), edema, and apoptosis. Maximal behavioral deficit occurred at 7 days of reperfusion. The comparison of behavioral score pertaining to the control and AG groups revealed significant differences and showed also a better time course in recovery (P < 0.05). Other than 3 and 4 groups, the amount of edema in AG treatment groups showed significant differences compared with control groups (P < 0.05). IFD was also significantly decreased in the AG treatment groups than controls. Most importantly, I/R-induced apoptosis were improved significantly on the 4th, 7(th), and 14th days of reperfusion in AG-treated groups compared to controls. In conclusion, our findings suggest that post-ischemic administration of AG exhibits protective effect against sciatic nerve I/R injury.

Effect of Aminoguanidine on the Conjunctival Histamine and Nitrite Levels in Experimental Conjunctivitis

Histamine and nitric oxide (NO) play pivotal roles in ocular surface hypersensitivity reactions, whereas the activity of their metabolic enzymes diamine oxidase (DAO) and NO synthase (NOS) may affect their function. This study aimed at investigating the effects of ocular administration of aminoguanidine (AMG), a multiple action DAO and NOS inhibitor, on the conjunctival histamine and nitrite levels in a model of experimental conjunctivitis. AMG, at 0.81, 81 or 81×10(3) μM, was instilled into the lower conjunctival fornix of normal and compound 48/80 (C48/80)-challenged eyes of male Wistar rats in the absence or presence of 40 mg/mL disodium cromoglycate. Histamine and nitrite were quantified in the conjunctival homogenate and lavage fluid 45 min and 6 h postchallenge, respectively. AMG induced no significant alterations in basal histamine and nitrite levels in the normal rat eye. In experimental conjunctivitis, AMG failed to modify the reduction in histamine content and partially circumvented the increases in nitrite levels observed during the early and late phase reactions, respectively. In the presence of disodium cromoglycate, AMG significantly increased the levels of both proinflammatory mediators in the normal rat eye. The data suggested that DAO may not be the main route of in situ histamine catabolism in the normal and C48/80-challenged rat conjunctiva, whereas NOS contributes to the phenotypic alterations observed in mast cell-dependent conjunctivitis. Mast cell stabilizing agents and AMG-modulated systems seem to interact through yet undefined mechanisms in the different phases of ocular hypersensitivity reactions.

Nitric oxide-mediated apoptosis in rat macrophages subjected to Shiga toxin 2 from Escherichia coli

Shiga toxin-producing Escherichia coli are important food-borne pathogens. The main factor conferring virulence on this bacterium is its capacity to secrete Shiga toxins (Stxs), which have been reported to induce apoptosis in several cell types. However, the mechanisms of this apoptosis have not yet been fully elucidated. In addition, Stxs have been shown to stimulate macrophages to produce nitric oxide (NO), a well-known apoptosis inductor.The aim of this study was to investigate the participation of NO in apoptosis of rat peritoneal macrophages induced by culture supernatants or Stx2 from E. coli. Peritoneal macrophages incubated in the presence of E. coli supernatants showed an increase in the amounts of apoptosis and NO production. Furthermore, inhibition of NO synthesis induced by addition of aminoguanidine (AG) was correlated with a reduction in the percentage of apoptotic cells, indicating participation of this metabolite in the apoptotic process. Similarly, treatment of cells with Stx2 induced an increase in NO production and amount of apoptosis, these changes being reversed by addition of AG. In summary, these data show that treatment with E. coli supernatants or Stx2 induces NO-mediated apoptosis of macrophages.