Administration Of L-NAME Research Articles

Angiotensin AT2 receptors and the baroreflex control of renal sympathetic nerve activity

Angiotensin AT2 receptors and the baroreflex control of renal sympathetic nerve activity

Regulation of MMP/TIMP by HUVEC transplantation attenuates ventricular remodeling in response to myocardial infarction

AimsWe elucidated the therapeutic potential of human umbilical vein endothelial cells (HUVECs) for ameliorating progressive heart failure in a myocardial infarction (MI) rat model. Main methodsMI was induced by ligation of left anterior descending artery, and HUVEC was transplanted 1week after MI. Cardiac function was evaluated by echocardiography, and histological analyses were performed. Key findingsPhosphate-buffered saline (MI-V, n=5) or HUVEC (MI-HV, n=5) were injected into the border zone and infarcted area 7days after ligation of the left coronary artery in rats. The MI-HV group showed attenuation of left ventricular (LV) remodeling compared with the MI-V group. In the infarcted myocardium, a few of injected HUVEC was retained up to 28days. The ratios of matrix metalloproteinase (MMP)-2 or MMP-9 to tissue inhibitor of metalloproteinase (TIMP)-1 or TIMP-3 were decreased in the MI-HV group compared with the MI-V group. In vivo zymography analysis showed that HUVEC transplantation decreased the activities of MMP-2 and MMP-9. In immunohistochemistry, decreased MMP-2 and increased TIMP-1 and TIMP-3 expression were observed at 48h after HUVEC transplantation. These effects on MMP/TIMP balance were inhibited by L-NAME administration (an eNOS inhibitor, 10mg/kg). NOS inhibition decreased the protein expressions of TIMP-1 and TIMP-3 but did not change the protein expressions of MMP-2 and MMP-9. SignificanceOur data suggest that altered balance between MMP and TIMP by HUVEC transplantation contributed to attenuation of ventricular remodeling after MI via eNOS.

Arginine NO-dependent and NO-independent effects on hemodynamics

l-arginine administration decreases mean arterial blood pressure (MABP), presumably by excess nitric oxide (NO) synthesis. However, some reports indicate that d-arginine, not a substrate of NO synthase (NOS), also induces hypotension. To clarify this phenomenon, the hemodynamic effects of l- and d-arginine and their modification by NOS inhibition with l-nitroarginine methyl ester (l-NAME) were assessed. MABP, cardiac output, stroke volume, heart rate and systemic vascular resistance were recorded in Sprague-Dawley rats under urethane or ketamine/diazepam anesthesia, with or without blockade of NO synthesis by l-NAME. Both stereoisomers of arginine induced a dose-related drop in MABP of similar magnitude and time course, but recovery from hypotension was slower in l-arginine than in d-arginine. The hypotension induced by both stereoisomers was due to a decrease in systemic vascular resistance (SVR) with increase in cardiac output (CO) and stroke volume (SV). Administration of l-NAME induced a pronounced increase in MABP and SVR, with decreases in CO and heart rate (HR). Infusion of l-arginine after l-NAME significantly decreased MABP and SVR at the highest dose while d-arginine failed to do so. After l-NAME, MABP was significantly lower under l-arginine than under d-arginine at all doses. These experiments suggest a dual mechanism in the hypotensive effect of l-arginine: a NO independent action on vascular resistance shared with d-arginine, and a NO dependent mechanism that becomes evident in the presence of NOS inhibition with l-NAME. Cardiac effects of NO do not appear to play a role in l-arginine hypotension.

A Noninvasive Metabolic Syndrome Model Using an Extremely Small Minipig, the Microminipig

Metabolic syndrome (MetS) induces serious complications; therefore, we developed a noninvasive MetS model using an extremely small minipig, the Microminipig. For 8 weeks, Microminipigs were administrated a high-fat and high-cholesterol diet (HFCD) for atherosclerosis and N(G)-nitro-l-arginine methyl ester (l-NAME) for inhibiting nitric oxide synthase. HFCD significantly increased serum low-density lipoprotein levels, l-NAME increased blood pressure and cardiac hypertrophy, and HFCD-induced aortal arteriosclerosis was accelerated by l-NAME administration. Endothelium-dependent relaxation of the coronary artery was remarkably decreased by l-NAME administration. This model may be useful for elucidating the mechanisms of MetS and developing new therapeutic medicines for its treatment.

Inhibition of Constitutive Nitric Oxide Synthase Does Not Influence Ventilation-Perfusion Matching in Normal Prone Adult Sheep With Mechanical Ventilation.

Local formation of nitric oxide in the lung induces vasodilation in proportion to ventilation and is a putative mechanism behind ventilation-perfusion matching. We hypothesized that regional ventilation-perfusion matching occurs in part due to local constitutive nitric oxide formation. Ventilation and perfusion were analyzed in lung regions (≈1.5 cm) before and after inhibition of constitutive nitric oxide synthase with N-nitro-L-arginine methyl ester (L-NAME) (25 mg/kg) in 7 prone sheep ventilated with 10 cm H2O positive end-expiratory pressure. Ventilation and perfusion were measured by the use of aerosolized fluorescent and infused radiolabeled microspheres, respectively. The animals were exsanguinated while deeply anesthetized; then, lungs were excised, dried at total lung capacity, and divided into cube units. The spatial location for each cube was tracked and fluorescence and radioactivity per unit weight determined. After administration of L-NAME, pulmonary artery pressure increased from a mean of 16.6-23.6 mm Hg, P = .007 but PaO2, PaCO2, and SD log(V/Q) did not change. Distribution of ventilation was not influenced by L-NAME, but a small redistribution of perfusion from ventral to dorsal lung regions was observed. Perfusion to regions with the highest ventilation (fifth quintile of the ventilation distribution) remained unchanged after L-NAME. We found minimal or no influence of constitutive nitric oxide synthase inhibition by L-NAME on the distributions of ventilation and perfusion, and ventilation-perfusion in prone, anesthetized, ventilated, and healthy adult sheep with normal gas exchange.

CORRECTION OF EXPERIMENTAL L-NAME-INDUCED PRE-ECLAMPSY BY INHIBITOR OF ARGINASE L-NORVALINE AND ITS COMBINATIONS WITH PREPARATIONS OF STANDARD TREATMENT SCHEME

Experimental L-NAME-induced pre-eclampsia model in rats was achieved by L-NAME administration from 14 to 20 pregnancy days. Blood pressure elevation, gestational proteinuria, placenta microcirculation impairing, vascular tone dysregulation, and L-norvaline (10 mg/kg) and conventional medications (methyldopa 0,086 mg/kg/day & amlodipine 0,5 mg/kg) result in the evident correction of the pathological changes in pre-eclampsia model. Despite good L-norvaline with conventional pre-eclampsia medications). This might be explained by different points of applications and allows to affect many different patho-genesis chains.

Can Sitaglipten Attenuate Hypertension, Myocardial Changes and Vascular Reactivity Induced by Long Term Blockade of Nitric Oxide Synthesis in the Rat?

Background: Glucagon-like peptide-1 (GLP-1) is an incretin hormone with insulinotropic properties that regulates glucose metabolism. GLP-1 receptors are the most extensively key modulators of lipid and glucose homeostasis. They are predominantly expressed in adipose tissues, some non adipose tissues including heart, kidney, spleen, and all relevant cells of the vasculature: endothelial cells, smooth muscle cells, and macrophages. The vascular distribution suggests their involvement in the control of cardiovascular function. Objective: The present experiment was designed to study the effect of sitaglipten alone or in combination with captopril on blood pressure, antioxidant enzymes, vascular reactivity and cardiac hypertrophy in NG-nitro-L-arginine methylester (L-NAME) induced hypertension in rats. Methods: One hundred male albino rats weighing from 150 - 200 g were included in this study. Rats were divided into two main groups. Group I, (20 rats) served as a control group for group II, and received 1 ml of physiological saline (0.9%), orally for seven weeks. Group II: hypertensive group, (80 rats) was given daily L-NAME in a dose of 40 mg/kg orally for seven weeks. Rats were further subdivided into A, B, C, and D, each of 20 rats. Group-A, received 1 ml of distilled water daily orally for six weeks, starting one week after L-NAME administration. Groups B, C and D were treated with daily sitaglipten (10 mg/kg b.wt. orally) and captopril (100 mg/kg b.wt. orally), alone or together for six weeks. Blood pressure, serum tumor necrosis factor-α (TNF-α), body weight (BW) and heart weight (HW) were measured. Malondialdehyde (MDA) and reduced glutathione (GSH) were estimated in cardiac tissues. Thoracic aorta was isolated and the aortic rings were allowed to achieve maximal tension by cumulative addition of phenylephrine (PE) (10-9-10-5 M) to the bath solution. Results: Sitaglipten and captopril, alone or together produced significant decreases in blood pressure and TNF-α. Higher oxidative stress accompanying hypertension was significantly reduced by sitaglipten and captopril treatment. The results showed that both drugs significantly attenuated the augmented contractile response to PE in hypertensive rats. In addition, they inhibited the cardiac hypertrophy (reduction in HW/BW ratio). Conclusion: These data suggest that DPP4 inhibitor (sitaglipten) “is away from being insulinotropic and regulates glucose metabolism”, contributes to normal regulation of blood pressure and exerts protective effects in hypertension via many mechanisms, as inhibition of generation of free radicals.

Possible role of nitric oxide in hepatic injury secondary to renal ischemia-reperfusion (I/R) injury.

Hepatic injury secondary to renal I/R injury has been documented in several studies. This study aimed to investigate the role of NO in hepatic injury secondary to renal I/R in rat model. Sprague-Dawley rats (n = 48) were divided into 4 equal groups; sham-operated, I/R injury group (45 min of bilateral renal ischemia), L-arginine group (I/R with 300 mg/kg L-arginine, 20 min before ischemia), L-NAME group (I/R with 50 mg/kg L-NAME, 20 min before ischemia). L-NAME (NO synthase inhibitor) caused significant elevation in serum creatinine, BUN, liver enzymes, liver histopathological damage score (p ≤ 0.05) and MDA production (p ≤ 0.001); on the other hand significantly decreased NO and GSH levels (p ≤ 0.05). L-arginine significantly decreased serum creatinine, BUN and GSH (p ≤ 0.05) and caused significant elevation in liver enzymes and NO (p ≤ 0.05), and also in MDA levels (p ≤ 0.001) in liver tissues. We conclude that endogenous NO might have protective effect against hepatic injury induced by renal I/R injury and inhibition of this endogenous NO by L-NAME or exogenous administration of NO (by L-arginine) might be harmful.

Effect of nitric oxide pathway regulation on water/sodium balance and renal function in a rodent model of acute liver and renal failure.

BackgroundThe pathomechanism of acute hepatorenal syndrome (HRS), a particular form of acute renal failure that occurs in the course of acute liver injury, is still poorly understood. The aim of our study was to estimate the influence of the activation and inhibition of the nitric oxide pathway on the water/sodium balance and development of acute renal failure in the course of HRS.Material/MethodsWe used male Sprague-Dawley rats in the acute galactosamine (Ga1N) model of HRS. The nitric oxide synthase (NOS) inhibitors L-NAME and L-arginine were administered intraperitoneally before and after liver damage.ResultsHRS developed in all tested groups. L-NAME increased osmotic clearance and urine volume more effectively before liver injury. Furthermore, administration of L-NAME increased creatinine clearance both before and after Ga1N injection. A double dose of L-NAME did not yield further improvement before Ga1N injection, but improved creatinine clearance after Ga1N intoxication. Injection of L-arginine increased sodium excretion and urine volume, but only after liver injury. Moreover, L-arginine injected after Ga1N caused significant improvement of the creatinine clearance in a dose-dependent manner.ConclusionsOur study shows that inhibition of the nitric oxide pathway improves parameters of water and sodium balance and prevents development of acute renal failure in the course of acute liver injury and liver failure. Activation of the nitric oxide system also has a favorable influence on water/sodium balance and renal failure, but only after liver injury.

Effects of chrysin on free radicals and enzymatic antioxidants in Nω-nitro-l-arginine methyl ester: Induced hypertensive rats

Objectives: To evaluate the effect of chrysin, a natural biologically active compound extracted from many plants, mushrooms, honey, and propolis on the tissue and circulatory antioxidant status and lipid peroxidation in Nω-nitro-L-ariginine methyl ester (L-NAME)-induced hypertensive rats. Materials and Methods: Hypertension was induced in adult male albino rats of the Wistar strain, weighing 180-220 g, by oral administration of l-NAME (40 mg/kg BWT/day) in drinking water for 4 weeks. Rats were treated with chrysin (25 mg/kg BWT/day) for 4 weeks. Results: The results showed significantly elevated levels of tissue malondialdehyde, protein carbonyl, and xanthine oxidase, and significantly lowered nonenzymatic antioxidant activity of glutathione reductase and glutathione-S-transferase in l-NAME-induced hypertensive rats compared with those in the control group. Supplementation of chrysin at the dosage of 25 mg/kg considerably decreased the levels of malondialdehyde, protein carbonyl, and xanthine oxidase and significantly increased the activities of glutathione reductase and glutathione-S-transferase in the tissues and blood compared with those in the unsupplemented l-NAME-induced hypertensive groups. Conclusions: Chrysin offers protection against free radical-mediated oxidative stress in rats with l-NAME-induced hypertension.

Effects on chrysin on lipid and xenobiotic metabolizing enzymes in l-NAME-induced hypertension

Objective: N ω -nitro-l-arginine methyl ester (l-NAME) is a non-specific nitric oxide (NO) synthase inhibitor, commonly used for the induction of NO-deficient hypertension. Hypertension is a significant risk factor in cardiovascular complications. Materials and Methods: This study was undertaken to investigate the effects of chrysin on lipid metabolizing enzymes, xenobiotic metabolizing enzymes, and microalbuminuria and N -acetyl-β-d-glucosaminidase (NAG) in urine in l-NAME-induced hypertensive rats. Hypertension was induced in adult male Wistar rats weighing 180-220 g by oral administration of l-NAME (40 mg/kg BW) in drinking water for 4 weeks. Rats were treated with chrysin (25 mg/kg BW) for 4 weeks. Results: The activity of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase increased significantly in the liver and kidney, whereas the activities of lipoprotein lipase and lecithin cholesterol acyl transferase decreased significantly in the plasma of hypertensive rats. Conclusions: The xenobiotic phase I enzymes, microalbuminuria, and NAG significantly increased, whereas xenobiotic phase II enzymes decreased in l-NAME-treated rats. Oral administration of chrysin reduced hyperlipidemia-related risk of hypertension.

Nitric oxide in the dorsal hippocampal area is involved on muscimol state-dependent memory in the step-down passive avoidance test

In the present study, the effects of intra-dorsal hippocampal (intra-CA1) injections of nitric oxide (NO) agents on muscimol state-dependent memory were examined in mice. A single-trial step-down passive avoidance task was used for the assessment of memory retrieval in adult male NMRI mice.Post-training intra-CA1 administration of a GABAA receptor agonist, muscimol (0.05 and 0.1μg/mouse) dose dependently induced impairment of memory retention. Pre-test injection of muscimol (0.05 and 0.1μg/mouse) induced state-dependent retrieval of the memory acquired under post-training muscimol (0.1μg/mouse, intra-CA1) influence.Pre-test injection of a NO precursor, l-arginine (1 and 2μg/mouse, intra-CA1) improved memory retention, although the low dose of the drug (0.5μg/mouse) did not affect memory retention.Pre-test injection of an inhibitor of NO-synthase, l-NAME (0.5 and 1μg/mouse, intra-CA1) impaired memory retention, although the low dose of the drug (0.25μg/mouse) did not affect memory retention.In other series of experiments, pre-test intra-CA1 injection of l-arginine (0.25 and 0.5μg/mouse) 5min before the administration of muscimol (0.1μg/mouse, intra-CA1) dose dependently inhibited muscimol state-dependent memory. Pre-test intra-CA1 administration of l-arginine (0.125, 0.25 and 0.5μg/mouse) by itself cannot affect memory retention.Pre-test intra-CA1 injection of l-NAME (0.25μg/mouse, intra-CA1) reversed the memory impairment induced by post-training administration of muscimol (0.1μg/mouse, intra-CA1). Moreover, pre-test administration of l-NAME (0.125 and 0.25μg/mouse, intra-CA1) with an ineffective dose of muscimol (0.025μg/mouse, intra-CA1) significantly restored the retrieval and induced muscimol state-dependent memory. Pre-test intra-CA1 administration of l-NAME (0.0625, 0.125 and 0.25μg/mouse) by itself cannot affect memory retention.It may be suggested that the nitric oxide in the dorsal hippocampal area play an important role in muscimol state-dependent memory.

Moderate and Deep Hypothermia Produces Hyporesposiveness to Phenylephrine in Isolated Rat Aorta

BackgroundModerate and severe hypothermia with cardiopulmonary bypass during aortic surgery can cause some complications such as endothelial cell dysfunction or coagulation disorders. This study found out the difference of vascular reactivity by phenylephrine in moderate and severe hypothermia.MethodsPreserved aortic endothelium by excised rat thoracic aorta was sectioned, and then down the temperature rapidly to 25℃ by 15 minutes at 38℃ and then the vascular tension was measured. The vascular tension was also measured in rewarming at 25℃ for temperatures up to 38℃. To investigate the mechanism of the changes in vascular tension on hypothermia, NG-nitro-L-arginine methyl esther (L-NAME) and indomethacin administered 30 minutes before the phenylephrine administration. And to find out the hypothermic effect can persist after rewarming, endothelium intact vessel and endothelium denuded vessel exposed to hypothermia. The bradykinin dose-response curve was obtained for ascertainment whether endothelium-dependent hyperpolarization factor involves decreasing the phenylnephrine vascular reactivity on hypothermia.ResultsFifteen minutes of the moderate hypothermia blocked the maximum contractile response of phenylephrine about 95%. The vasorelaxation induced by hypothermia was significantly reduced with L-NAME and indomethacin administration together. There was a significant decreasing in phenylephrine susceptibility and maximum contractility after 2 hours rewarming from moderate and severe hypothermia in the endothelium intact vessel compared with contrast group.ConclusionThe vasoplegic syndrome after cardiac surgery might be caused by hypothermia when considering the vascular reactivity to phenylephrine was decreased in the endothelium-dependent mechanism.

Low nitric oxide bioavailability upregulates renal heparin binding EGF-like growth factor expression

Decreased nitric oxide bioavailability plays an important role in the initiation and progression of diabetic nephropathy, but the underlying mechanisms remain unclear. Here, we found that heparin binding epidermal growth factor-like growth factor (HB-EGF) expression levels increased in the kidneys of both endothelial nitric oxide synthase (eNOS) knockout and eNOS knockout diabetic (Lepr db/db) mice as early as 8 weeks of age. Further increases in expression were only seen in eNOS knockout diabetic mice and paralleled the progression of glomerulopathy. HB-EGF expression increased in endothelium, podocytes, and tubular epithelial cells. In cultured glomerular endothelial cells, the nitric oxide synthase inhibitors NG-nitro-L-arginine methyl ester (L-NAME) or L-N5-(1-Iminoethyl) ornithine increased HB-EGF protein expression. Administration of L-NAME dramatically increased renal HB-EGF expression and urinary HB-EGF excretion in diabetic mice. On the other hand, replenishing nitric oxide with sodium nitrate in eNOS knockout diabetic mice reduced urinary HB-EGF excretion and inhibited the progression of diabetic nephropathy. Furthermore, specific deletion of HB-EGF expression in endothelium attenuated renal injury in diabetic eNOS knockout mice. Thus, our results suggest that decreased nitric oxide bioavailability leads to increased HB-EGF expression, which may be an important mediator of the resulting progressive diabetic nephropathy in eNOS knockout diabetic mice.

Renoprotective effect of sitagliptin against hypertensive nephropathy induced by chronic administration of L-NAME in rats: Role of GLP-1 and GLP-1 receptor

The present study was undertaken to assess the possible protective effects of sitagliptin, a dipeptidyl peptidase 4-inhibitor (DPP4), against Nω-nitro-L-arginine methyl ester (L-NAME) induced hypertensive nephropathy in rats. Hypertension was induced in adult rats by administration of L-NAME for 6 weeks. Rats were treated with sitagliptin (10mg/kg/day or 30mg/kg/day) for six weeks. Chronic L-NAME administration resulted in depletion of serum nitric oxide (NO) associated with elevation in the mean arterial pressure. When compared with the control group; serum urea, serum creatinine, albuminuria, urinary N-acetyl-ß-d-glucosaminidase (NAG) level and renal tissue malondialdhyde (MDA) content were significantly elevated, while creatinine clearance, serum level of glucagon like peptide-1 (GLP-1) as well as renal tissue superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) activities were signifcantly decreased in L-NAME treated group. Renal expression of mRNA for eNOS and GLP-1 receptors were reduced in the L-NAME treated group as compared with the control group. Treatment with sitagliptin (10mg/kg or 30mg/kg) successfully ameliorated the deleterious effects of L-NAME on the all tested parameters. Our study indicates a novel protective effect of sitagliptin against L-NAME induced hypertensive nephropathy. An effect which is mediated through, increasing serum level of GLP-1, upregulation of GLP-1 receptors, which in turn, lead to induction of expression eNOS, increased serum NO level, tandem with decreased lipid perodixation and restore the antioxidant defense mechanisms. It is worth mentioning that the effects produced by sitaglipin (30mg/kg) were superior to the effects obtained by the lower dose.

Abstract 384: Tumor Necrosis Factor-alpha Antagonism Attenuates Hypertension and Renal Injury Induced by Chronic Blockade of Nitric Oxide and High Salt Intake in Mice

Earlier, we demonstrated that systemic blockade of nitric oxide (NO) generation by acute infusion of nitro-L-arginine methyl ester (L-NAME) in mice increases plasma and renal levels of tumor necrosis factor-alpha (TNF-α). In the present study, we examined the role of TNF-α in mediating hypertension and renal injury responses to chronic NO blockade by evaluating the responses to chronic administration of L-NAME (0.05 μg/g/min; by osmotic mini-pump) for 3 wks in mice (C57BL6) treated with or without TNF-α receptor antagonist, etanercept (ETN; 5 mg, ip, every alternate day). These mice were given either normal (NS; 0.03% NaCl) or high salt (HS; 4% NaCl) containing diets. Systemic blood pressure (BP) was measured by tail-cuff plethysmography. At the end of the experimental period, mice were sacrificed to collect plasma and renal tissue samples to measure TNF-α level by ELISA and to determine the extent of tissue injury such as glomerulosclerosis (GS; PAS staining) and renal interstitial fibrosis (RIF; Trichrome staining). L-NAME treatment caused increase in BP which was greater in HS (104±3 to 139±3 mmHg; n=6) than in NS group (96±6 to 124±6 mmHg; n=6). ETN treatment significantly attenuated this increase in BP in both L-NAME+HS (119±11 mmHg; n=6) and in L-NAME+NS (115±8 mmHg, n=6) groups. Renal tissue level of TNF-α was higher in L-NAME+NS (664±100 vs 325±73 pg/mg protein) and in L-NAME+HS (391±38 vs 114±17 pg/mg protein) groups compared to the levels in groups given NS (n=5) or HS (n=5) diet alone. However, the changes in plasma level of TNF-α due to chronic L-NAME treatment were minimal. ETN treatment lowered renal TNF-α level in L-NAME+NS (356±60 pg/mg protein) and in L-NAME+HS (259±65 pg/mg protein) groups. L-NAME treatment significantly increased GS (7.1±1.0 vs 17.9±2.3 % sclerosis area) and RIF, (1.5±0.1 vs 5.8±0.6 % fibrotic area) in HS group. However, these changes were minimal in NS group (GS, 10.3±1.0 vs 13.2±1.5 % and RIF, 1.3±0.1 vs 2.4±0.3 %). ETN treatment markedly attenuated the GS (11.8±0.4% and 11.9±0.6 %) and RIF (2.6±0.3% and 1.9±0.3%) both in L-NAME+HS and in L-NAME+NS groups. These data demonstrate that an enhancement in TNF-α activity is involved in mediating hypertension and renal injury responses to chronic NO blockade and HS intake.

13. Anti-inflammatory role of L-NG-Nitroarginine Methyl Ester in a chronic model of depression

The role of nitric oxide (NO) in the neurodegenerative disorders is well illustrated. The close relationship of NO level and the inflammation points out the clinical relevance of NO in depressive disorder. Present study evaluated the neuroprotective role of L-NAME, a NO synthase blocker in chronic restraint hypoxia (CRH) induced depressive behaviour. Briefly four groups of rat were exposed to CRH for 21 days. Group 1 and 2 served as normoxic control group (NOR + VEH, NOR + DRUG), group 3 and 4 served as stress exposed groups (CRH + VEH, CRH + DRUG) and the 5th group was LPS (Lipopolysaccharide) + DRUG. On the last day behavioural assessment was done and immediately brain sample were isolated for histology and biochemical parameters. IHC, ELISA and western blot were used to study the expression of stress markers following CRH exposure. Our results show that L-NAME administration to rats improved the exploratory and rearing behaviour and also reduced despair behaviour. DCX, a marker for neuronal migration and neurogenesis was increased significantly along with TRAF-2 and significant decreased in the expression of IL-1 receptor, NF-kB, iNOS, Cox-2, nNOS, H3K9 (epigenetic marker), nitric oxide and proinflammatory cytokines suggesting the role of L-NAME in buffering the stress induced behavioural impairment. From the above study it can be concluded that L-NAME treatment improves functional outcomes of rats during CRH exposure. Inhibiting NO with L-NAME increases neurogenesis and reduces inflammation.

Neuroprotective effect of tadalafil, a PDE-5 inhibitor, and its modulation by L-NAME in mouse model of ischemia-reperfusion injury

BackgroundThe present study investigates the neuroprotective effect of tadalafil, a selective phosphodiesterase-5 inhibitor, in a mouse model of ischemia-reperfusion injury. Materials and methodsBilateral carotid artery occlusion for 12 min followed by reperfusion for 24 h was employed to produce ischemia-reperfusion-induced cerebral injury in male Swiss mice. Cerebral infarct size was measured using triphenyltetrazolium chloride staining. Memory was assessed using Morris water maze test. Degree of motor incoordination was evaluated using inclined beam walk test, rota-rod test, and lateral push test. Brain nitrite/nitrate, brain acetylcholinesterase activity, brain thiobarbituric acid reactive species, and glutathione levels were also estimated. ResultsBilateral carotid artery occlusion, followed by reperfusion, produced a significant rise in cerebral infarct size, brain nitrite/nitrate levels, acetylcholinesterase activity, and thiobarbituric acid reactive species level along with a fall in glutathione. A significant impairment of memory and motor coordination was also noted. Pretreatment of tadalafil significantly attenuated the above effects of ischemia-reperfusion injury. Tadalafil-induced neuroprotective effects were significantly attenuated by administration of L-NAME, a nonselective nitric oxide synthase inhibitor. ConclusionsResults indicate that tadalafil exerts neuroprotective effects, probably through nitric oxide–dependent pathways. Therefore, phosphodiesterase-5 can be explored as an important target to contain ischemia-reperfusion injury.

Abstract 310: Role of Cardiac Fibroblast in Cardioprotective Effects of Prior Transient ACE Inhibition

Prior treatment with the ACE inhibitor enalapril followed by washout protects against nitric oxide synthase inhibitor (L-NAME) induced fibrosis, cellular proliferation, and cardiac dysfunction. The present study investigated i) whether in vivo L-NAME administration induces a change in cardiac fibroblast phenotype that persists in vitro, ii) whether prior ACE inhibition protects against L-NAME induced changes in cardiac fibroblasts. SHR were divided into 3 groups: Control, L-NAME (C+L: 7d), enalapril+L-NAME (E+L: 14d enalapril + 14d washout + 7d L-NAME). MAP was measured by radiotelemetry (n=5-9), injury assessed by histology (n=6-10), and heart weight to body weight (HW/BW) was determined after 0 or 7 days of L-NAME in C+L and E+L (n=6-10). In separate rats cardiac fibroblasts were isolated after 7 days of L-NAME (C+L, E+L) or placebo (Con) and cultured to passage 1 (n=10-12). Gene expression was measured by quantitative real-time PCR. L-NAME increased MAP in C+L (22±4.1%) and E+L (21±3.6%) rats. Prior enalapril induced a persistent 13% reduction in HW/BW. L-NAME increased heart mass in E+L (7%) but not C+L; however, HW/BW remained 8% lower than C+L at sacrifice. L-NAME induced infarct in 70% of C+L and 40% of E+L hearts. Cardiac fibroblasts demonstrated a significant increase in proliferation rate in C+L, but not E+L, relative to control (C+L: 1.75-fold vs. con; E+L 1.09-fold vs. con). Fibroblasts from C+L hearts tended to have increased Collagen I and III gene expression. Despite hypertension, cardiac injury, and increased HW/BW; fibroblasts isolated from E+L proliferated at the same rate as those from control. In contrast, those isolated from C+L were hyperproliferative with a tendency toward increased capacity for collagen production. It may be that the fibroblast phenotype from E+L hearts would protect against infarct expansion and account, in part, for the previously reported cardioprotection in these rats.

Nitric oxide mediates the beneficial effect of chronic naltrexone on cholestasis-induced memory impairment in male rats

Recent studies suggest an augmentation of endogenous opioids following bile duct ligation (BDL) and their pivotal role in the pathophysiology of cholestasis. In this study, the effect of naltrexone, an opioid receptor antagonist, was determined on cholestasis-induced memory impairment and the possible involvement of nitric oxide (NO) in this effect. Male Albino-Wistar rats were randomized to sham-operated and BDL-operated groups. In each group, animals were treated for up to 28 days with saline; naltrexone (10 mg/kg); naltrexone and N(G)-nitro-L-arginine methyl ester (L-NAME), a nonselective nitric oxide synthase (NOS) inhibitor (3, 10 mg/kg); naltrexone and aminoguanidine, an inducible NOS inhibitor (100 mg/kg); or methylnaltrexone, a peripherally acting opioid receptor antagonist (3 mg/kg, intraperitoneal). Spatial recognition memory was determined in a Y-maze task on the day before surgery and days 7, 14, 21, and 28 after surgery. Memory performance was impaired 14 days after BDL in cholestatic rats and was significantly reversed by chronic treatment with naltrexone at days 14, 21, and 28 after BDL. On day 21 after BDL, chronic L-NAME produced only a nonsignificant decrease in the beneficial effect of naltrexone, whereas on day 28, chronic administration of both L-NAME and aminoguanidine significantly reversed this effect of naltrexone. It is therefore shown in this study that naltrexone improves BDL-induced memory deficit in rats. We conclude that the memory impairment in cholestatic rats might be because of an increase in the level of endogenous opioids and that naltrexone improved the spatial recognition memory by antagonizing opioid receptors. The observation that the procognitive effect of naltrexone is counteracted either by general inhibition of NOS enzymes or by selective inhibition of inducible NOS suggests the nitrergic pathway as a probable mechanism involved in the amelioration of spatial recognition memory by naltrexone in BDL rats.