arl-17477 and 7-nitroindazole

Severe hemorrhage can lead to global ischemia and hemorrhagic shock (HS), resulting in multiple organ failure (MOF) and death. Restoration of blood flow and re-oxygenation is associated with an exacerbation of tissue injury and inflammatory response. The neuronal nitric oxide synthase (nNOS) has been implicated in vascular collapse and systemic inflammation of septic shock; however, the role of nNOS in HS is poorly understood. The aim of this study was to evaluate the role of nNOS in the MOF associated with HS.Rats were subjected to HS under anesthesia. Mean arterial pressure was reduced to 30  mmHg for 90  min, followed by resuscitation with shed blood. Rats were randomly treated with two chemically distinct nNOS inhibitors [ARL 17477 (1 mg/kg) and 7-nitroindazol (5 mg/kg)] or vehicle upon resuscitation. Four hours later, parameters of organ injury and dysfunction were assessed.HS was associated with MOF development. Inhibition of nNOS activity at resuscitation protected rats against the MOF and vascular dysfunction. In addition, treatment of HS rats with nNOS inhibitors attenuated neutrophil infiltration into target organs and decreased the activation of NF-κB, iNOS expression, NO production, and nitrosylation of proteins. Furthermore, nNOS inhibition also reduced the levels of pro-inflammatory cytokines TNF-α and IL-6 in HS rats.In conclusion, two distinct inhibitors of nNOS activity reduced the MOF, vascular dysfunction, and the systemic inflammation associated with HS. Thus, nNOS inhibitors may be useful as an adjunct therapy before fluids and blood administration in HS patients to avoid the MOF associated with reperfusion injury during resuscitation.

Topics: Amidines; Animals; Indazoles; Interleukin-6; Male; Multiple Organ Failure; Neutrophil Infiltration; NF-kappa B; Nitric Oxide Synthase Type I; Rats; Rats, Wistar; Shock, Hemorrhagic; Tumor Necrosis Factor-alpha

We examined the relative contributions from nitric oxide (NO) and catecholaminergic pathways in promoting cerebral arteriolar dilation during hypoglycemia (plasma glucose congruent with 1.4 mM). To that end, we monitored the effects of beta-adrenoceptor (beta-AR) blockade with propranolol (Pro, 1.5 mg/kg iv), neuronal nitric oxide synthase (nNOS) inhibition with 7-nitroindazole (7-NI, 40 mg/kg ip) or ARR-17477 (300 microM, via topical application), or combined intravenous Pro + 7-NI or ARR-17477 on pial arteriolar diameter changes in anesthetized rats subjected to insulin-induced hypoglycemia. Additional experiments, employing topically applied TTX (1 microM), addressed the possibility that the pial arteriolar response to hypoglycemia required neuronal transmission. Separately, Pro and 7-NI elicited modest but statistically insignificant 10-20% reductions in the normal ~40% increase in arteriolar diameter accompanying hypoglycemia. However, combined Pro-7-NI was accompanied by a >80% reduction in the hypoglycemia-induced dilation. On the other hand, the combination of intravenous Pro and topical ARR-17477 did not affect the hypoglycemia response. In the presence of TTX, the pial arteriolar response to hypoglycemia was lost completely. These results suggest that 1) beta-ARs and nNOS-derived NO interact in contributing to hypoglycemia-induced pial arteriolar dilation; 2) the interaction does not occur in the vicinity of the arteriole; and 3) the vasodilating signal is transmitted via a neuronal pathway.

Topics: Action Potentials; Adrenergic beta-Antagonists; Amidines; Animals; Arterioles; Blood Glucose; Cerebrovascular Circulation; Enzyme Inhibitors; Hypoglycemia; Indazoles; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Pia Mater; Propranolol; Rats; Rats, Sprague-Dawley; Receptors, Adrenergic, beta; Tetrodotoxin; Vasodilation

Previous studies had reported that the nitric oxide (NO) donor, sodium nitroprusside (SNP), retarded and the non-specific NO synthase (NOS) inhibitor, Nomega-nitro-L-arginine methyl ester (L-NAME), enhanced acquisition of classically conditioned responses (CRs). These effects of IV SNP and IP L-NAME on CR acquisition occurred in the absence of any effect on non-associative processes or performance variables and at a time when there were no alterations in blood pressure or heart rate.. In this study, we examined whether the changes in associative learning produced by L-NAME and SNP were due to their central effects on NO content of brain. To this end, we examined the effects of the selective neuronal NOS inhibitors 7-nitroindazole (7-NI) and AR-R 17477 and the effects of central (ICV) administration of the NO donor SNP on learning.. Effects of drugs on CR acquisition were determined during classical conditioning of the rabbit's nictitating membrane (NM) response. Explicitly unpaired presentations of conditioned stimuli (CSs) and unconditioned stimuli (USs) were employed to measure non-associative levels of responding and unconditioned response (UR) topography.. The SC injection of 7-NI and AR-R 17477 significantly enhanced associative learning while ICV administration of SNP significantly retarded learning.. Production of NO within the brain by neuronal NOS normally acts to retard associative learning presumably by decreasing excitability within neuronal circuits involved in the acquisition of the classically conditioned NM reflex.

Topics: Amidines; Animals; Association Learning; Conditioning, Operant; Enzyme Inhibitors; Female; Indazoles; Injections, Intraventricular; Male; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitroprusside; Rabbits

A subset of familial cases of amyotrophic lateral sclerosis are linked to missense mutations in copper/zinc superoxide dismutase type 1. Patients with missense mutations in copper/zinc superoxide dismutase type 1 develop a paralytic disease indistinguishable from sporadic amyotrophic lateral sclerosis through an unknown toxic gain of function. Nitric oxide reacts with the superoxide anion to form the strong oxidant, peroxynitrite, which participates in neuronal injury in a variety of model systems. Peroxynitrite is an alternate substrate for copper/zinc superoxide dismutase type 1, causing catalytic nitration of tyrosine residues in other proteins. Mutations in copper/zinc superoxide dismutase type 1 may disrupt the active site of the enzyme and permit greater access of peroxynitrite to copper, leading to increased nitration by peroxynitrite of critical cellular targets. To investigate whether neuronal-derived nitric oxide plays a role in the pathogenesis of familial amyotrophic lateral sclerosis, we examined the effects of three different nitric oxide synthase inhibitors: a non-selective nitric oxide synthase inhibitor, nitro-L-arginine methyl ester; a relatively selective inhibitor of neuronal nitric oxide synthase, 7-nitroindazole; and a novel highly selective neuronal nitric oxide synthase inhibitor, AR-R 17,477, in transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 (Gly-->Ala at position 93; G93A) containing a high transgene copy number and a low transgene copy number. AR-R 17,477, but not nitro-L-arginine methyl ester or 7-nitroindazole, significantly prolonged survival in both the high and low transgene transgenic mice. To determine whether neuronal nitric oxide synthase is involved in the pathogenesis resulting from the familial amyotrophic lateral sclerosis copper/zinc superoxide dismutase type 1 mutation, we produced mice with the copper/zinc superoxide dismutase type 1 mutation which lack the neuronal nitric oxide synthase gene. The transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1 on neuronal nitric oxide synthase null background do not live significantly longer than transgenic mice expressing a familial amyotrophic lateral sclerosis-linked mutant human copper/zinc superoxide dismutase type 1. Western blot analysis indicates the presence of two neuronal nitric oxide synthase-like immunoreact

Topics: Amidines; Amyotrophic Lateral Sclerosis; Animals; Catalysis; Enzyme Inhibitors; Indazoles; Isoenzymes; Mice; Mice, Transgenic; NG-Nitroarginine Methyl Ester; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Phenotype; Spinal Cord

We have investigated the neuroprotective effects of combining an NMDA or AMPA receptor antagonist with a nitric oxide synthase (NOS) inhibitor in the gerbil model of global cerebral ischaemia. Ischaemia was induced by occlusion of the common carotid arteries for 5 min. (5R,10S)-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,1 0-imine (MK-801, 2.5 mg/kg i.p.) or (3S,4aR,6R,8aR)-6-[2-(1(2)H-tetrazole-5-yl)]decahydroisoq uinoline-3-carboxylic acid (LY293558, 20 mg/kg i.p.) and 7-nitroindazole (25 mg/kg i.p.) or N-[4-(2-[[(3-chlorophenyl)methyl]amino]ethyl) phenyl]-2-thiophenecarboximidamide dihydrochloride (ARL17477, 25 mg/kg i.p.) were administered alone or in combination (i.e., MK-801 with 7-nitroindazole or ARL17477 or LY293558 with 7-nitroindazole or ARL17477). In the present studies, both MK-801 and LY293558 provided significant degree of neuroprotection, while 7-nitroindazole and ARL17477 also provided some neuroprotection, which failed to reach significance in every case. However, the combination of MK-801 with 7-nitroindazole or ARL17477 provided 21% or 44% greater protection than the total protection or either alone. Likewise, the combination of LY293558 with 7-nitroindazole or ARL17477 provided 14.5% and 35% greater protection than total protection of either compound alone. These results indicate that several pathways contribute to ischaemic cell death and combining excitatory amino antagonists and NOS inhibitors provides greater protection than either alone. Therefore, combination therapy should be considered as an approach for treating ischaemic conditions.

Topics: Amidines; Animals; Brain Ischemia; Carotid Arteries; Dizocilpine Maleate; Drug Synergism; Enzyme Inhibitors; Excitatory Amino Acid Antagonists; Gerbillinae; Hippocampus; Indazoles; Isoquinolines; Male; Neuroprotective Agents; Nitric Oxide Synthase; Receptors, AMPA; Receptors, N-Methyl-D-Aspartate; Tetrazoles