AIMTo investigate the causative role of nitric oxide synthase (NOS) and nitric oxide (NO) in neurotoxicity of beta-amyloid (Abeta) and the pathogenesis of Alzheimer's disease (AD).

METHODSUsing behavioral and neuropathological methods, we observed the effects of Abeta(1-40) injection into hippocampi on rats learning and memory in Y maze and on the neuropathology in hippocampi. The intervention by intraperitoneal administration of aminoguanidine (AG), a selective inducible NOS (iNOS) inhibitor, and 7-nitroindazole (7-NI), a selective neuronal NOS (nNOS) inhibitor, in the neurotoxicity of Abeta(1-40) was studied then.

RESULTSThe capability of acquisition and retrieval in Y maze and local neurons in hippocampus of the rats were impaired significantly after Abeta(1-40) injection. Intraperitoneal administration of AG, but not 7-NI, could prevent the damages caused by Abeta(1-40) injection above-mentioned.

CONCLUSIONiNOS/NO participates in the mechanisms of Abeta-induced neurotoxicity and may play an important role in the pathogenesis of AD.

Alzheimer Disease ; metabolism ; pathology ; Amyloid beta-Peptides ; metabolism ; toxicity ; Animals ; Guanidines ; pharmacology ; Indazoles ; pharmacology ; Male ; Maze Learning ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase ; antagonists & inhibitors ; Nitric Oxide Synthase Type II ; metabolism ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the antioxidant and anti-endotoxin effects of propofol on endothelial cells and the possible mechanisms.

METHODSCultured endothelial cells were treated with hydrogen peroxide (H(2)O(2)), propofol + H(2)O(2), lipopolysaccharide (LPS) and propofol + LPS, respectively. Endothelial cell damage was monitored for possible lactic dehydrogenase (LDH) release. The transcription and the protein expression levels of endothelial nitric oxide synthase (eNOS) were measured.

RESULTSLDH release was higher in groups treated with H(2)O(2) or LPS than in the control group. After pretreatment with propofol, the effects induced by H(2)O(2) were attenuated, but propofol did not decrease the LDH release induced by LPS. Both H(2)O(2) and LPS significantly increased the eNOS transcript levels and the increases were significantly attenuated after pretreatment with propofol. Both H(2)O(2) and LPS significantly increased the eNOS protein expression and the increase was attenuated after pretreatment with propofol.

CONCLUSIONPropofol could protect endothelial cells against oxidative stress by inhibiting eNOS transcription and protein expression, but could not antagonise endotoxin induced cell injuries.

Antioxidants ; pharmacology ; Endothelium, Vascular ; cytology ; drug effects ; metabolism ; Endotoxins ; antagonists & inhibitors ; Free Radical Scavengers ; pharmacology ; Humans ; In Vitro Techniques ; Lipopolysaccharides ; pharmacology ; Nitric Oxide ; pharmacology ; Nitric Oxide Synthase ; biosynthesis ; Nitric Oxide Synthase Type III ; Propofol ; pharmacology

OBJECTIVETo observe the effect of a new synthetic tripeptide [Arg(NO(3))- Lys(OCH(3))- Arg(NO(3))] on L-arginine/NO pathway in the macrophage cell strain RAW246.7.

METHODSThe cultured macrophages exposed to lipopolysaccharide (LPS, 1 microg/L) treatment were randomly divided into 3 groups (n=6) and treated with distilled water, 1x10(-4) mol/L tripeptide and 1x10(-4) mol/L L-arginine, NG-monomethyl-L-arginine (L-NMMA) for 24 h, respectively. The macrophages were incubated for 24 h with LPS (1 microg/L) and in the presence of different concentrations of L-arginine (0 to 2 mmol/L), or in normal culture medium (containing 0.5 mmol/L L-arginine) for 24 h with LPS (1 microg/L) and in the presence of tripeptide of 0 to 10x10(-4) mol/L. The changes of [(3)H]-L-arginine transport and NO production from the macrophages were measured.

RESULTNO release from macrophages incubated in the LPS-containing culture medium was 50 folds, and [(3)H]-L-arginine uptake 2.7 folds that in cells in normal culture medium. Tripeptide (1x10(-4) mol/L) inhibited [(3)H]-L-arginine transport and NO production by 67% and 71% respectively. The effect of tripeptide was stronger than L-NMMA (P<0.05). Extracellular L-arginine caused a concentration-dependent increase in nitrite production, which reached the maximum at concentrations above 0.5 mmol/L Km for nitrite production of 0.162+/-0.015 mmol/L and Vmax of 91.2+/-2.3 micromol/(24h.10(6) cells). L-arginine transport and NO production were inhibited by tripeptide, but their dose-dependent pattern of changes was different with EC50 of 0.21x10(-4) mol/L and 1.27x10(-4) mol/L, respectively.

CONCLUSIONSActivation of macrophages with LPS induces nitrite accumulation in the culture medium, which is dependent on the presence of extracellular L-arginine. The tripeptide induces dysfunction of L-arginine/NO pathway in macrophages, potently inhibits L-arginine transport and competitively combine the active sites of nitric oxide synthase.

Arginine ; metabolism ; Biological Transport ; drug effects ; Cells, Cultured ; Humans ; Lipopolysaccharides ; Macrophages ; cytology ; metabolism ; Nitric Oxide ; biosynthesis ; Nitric Oxide Synthase ; antagonists & inhibitors ; Oligopeptides ; pharmacology

Nitric oxide (NO), which is involved in the regulation of the cardiovascular system, nervous system, immune system, reproductive system, digestive system and other physiological activities, is an important biological substance with activity. Under normal physiological conditions, neuronal nitric oxide synthase (nNOS) can precisely regulate the nervous system NO production, release, diffusion and inactivation processes. But an excess of NO associates with the development of cerebral ischemia, Alzheimer's and Parkinson's psychosis nervous system diseases, while inhibition of nNOS activity can regulate the content of NO in vivo, and produce a therapeutic effect on some of the nervous system diseases. This review mainly describes the structure and regulation of nNOS and recent developments of small molecule inhibitors of nNOS.
Alzheimer Disease ; physiopathology ; Brain Ischemia ; physiopathology ; Humans ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase Type I ; antagonists & inhibitors ; metabolism ; Parkinson Disease ; physiopathology

Animals ; Brain ; metabolism ; Brain Injuries ; metabolism ; Enzyme Inhibitors ; pharmacology ; Guanidines ; pharmacology ; Neuroprotective Agents ; pharmacology ; Nitric Oxide ; metabolism ; Nitric Oxide Synthase Type II ; antagonists & inhibitors ; Rats

To investigate the effects of nitric oxide (NO) on the pleural lymphatic stomata and lymph absorption from the pleural cavity, the NOS (nitric oxide synthase) inhibitor N(omega)-nitro-L-arginine-methyl-ester (L-NAME) and the NO donor isosorbide dinitrate (ISDN) were injected into the peritoneal cavity of the rats respectively. Trypan blue was used as a tracer. Then the concentrations of NO and trypan blue in the blood serum were measured, and the ultrastructural changes in pleural lymphatic stomata were observed under a scanning electron microscope (SEM) and studied by a computer image processing system attached to SEM. It turned out that the concentration of NO in the serum was 49.34+/-18.47 micromol/L, and the area and density of the pleural lymphatic stomata were 6.80+/-1.13 microm(2) and 170.24+/-66.60 /0.1 mm(2) respectively in the NO donor group. The concentration of NO reduced to 17.72+/-6.58 micromol/L, and the area and density of the pleural lymphatic stomata were 5.72+/-1.54 microm(2) and 61.71+/-12.73/0.1 mm(2) in the NOS inhibitor group. We found that the area and density of the pleural lymphatic stomata were positively correlated with the NO quantity. After the tracer was injected into the pleural cavity, the NO donor group exhibited a higher trypan blue concentration than the control group. The ability of the pleura to absorb trypan blue was enhanced because of the large opening of the stomata. It is suggested that NO can increase lymph absorption of the pleura by relaxing pleural lymphatic stomata.
Animals ; Lymphatic System ; physiology ; NG-Nitroarginine Methyl Ester ; pharmacology ; Nitric Oxide ; blood ; Nitric Oxide Synthase ; antagonists & inhibitors ; Peritoneal Stomata ; ultrastructure ; Rats

AIMTo search for novel compounds with potent nNOS inhibitory activity for the treatment of Alzheimer's disease.

METHODSThe target compounds were obtained by introducing benzenealkyl groups into the structure of isothioureas. nNOS inhibitory activity assays were conducted for the target compounds.

RESULTSSixteen benzenealkyl isothiourea compounds (I1-16) were synthesized by three different synthetic methods from benzylamine (1) or (substituted) phenethylamine (2). Compounds I1-6 were synthesized from 1 or 2 by reaction with benzoyl isothiocyanate to form the corresponding benzoylthioureas 3 or 4, followed by hydrolysis with 10% sodium hydroxide solution, then S-alkylation with methyl iodide or ethyl iodide. I7-14 were synthesized from 1 or 2 by reaction with methyl isothiocyanate to form the corresponding 1, 3-disubstituted thioureas 7 or 8 which were S-alkylated with methyl iodide or ethyl iodide. I15 and I16 were synthesized from 2 by reaction with dimethyl cyanodithioimidocarbonate. The structures of compounds I1-16 were confirmed by MS, IR, 1HNMR and elementary analysis. The results of preliminary pharmacological test showed that all compounds possessed nNOS inhibitory activity, among which compounds I8, I12 and I14 had good activity.

CONCLUSIONCompounds I8, I12 and I14 showed superior pharmacological profiles to the control compound S-methyl-N-(4-methoxyphenyl) isothiourea. The IC50 values of compounds I8, I12 and I14 inhibiting nNOS were 8.13 x 10(-7) mol.L-1, 1.74 x 10(-7) and 2.23 x 10(-7) mol.L-1 respectively, and it is worth further studying.

Animals ; Cattle ; Cells, Cultured ; Hippocampus ; cytology ; enzymology ; Inhibitory Concentration 50 ; Molecular Structure ; Nerve Tissue Proteins ; antagonists & inhibitors ; metabolism ; Nitric Oxide Synthase ; antagonists & inhibitors ; metabolism ; Nitric Oxide Synthase Type I ; Structure-Activity Relationship ; Thiourea ; analogs & derivatives ; chemical synthesis ; chemistry ; pharmacology

OBJECTIVETo explore the effects of intrathecal injection of neuronal nitric oxide synthase (nNOS) inhibitors 7-Nitroindazole (7-Ni) and inducible nitric oxide synthase(iNOS) inhibitors aminoguanidine (AG) on the behavioral changes of morphine-induced dependent and withdrawal rats; the expression of Fos, nNOS and iNOS in spinal cord.

METHODSTo set up morphine dependence model, rats were subcutaneously injected with morphine (twice a day, for 5 d). The dose of morphine was 10 mg/kg in the first day and was increased by 10 mg/ kg every day. On day 6, 4 h after the injection of morphine (50 mg/kg), morphine withdrawal syndrome was precipitated by an injection of naloxone (4 mg/kg ip). 7-Ni, an nNOS inhibitor or iNOS inhibitors AG were intrathecally injected 30 min before the administration of naloxone respectively. The scores of morphine withdrawal symptom and morphine withdrawal-induced allodynia were observed. One hour after naloxone-precipitated withdrawal, Fos protein expression was assessed by immunohistochemical analysis and Western blot was used to detect the expression of nNOS and iNOS in the rat spinal cord.

RESULTSIntrathecal administration of nNOS inhibitor 7-Ni and iNOS inhibitors AG decreased the scores of morphine withdrawal, attenuated morphine withdrawal-induced allodynia and also inhibited the increase of Fos protein expression in the spinal cord of morphine withdrawal rats. nNOS and iNOS positive neurons in dorsal horn in nNOS group and iNOS group were significantly lower than that in withdrawal group. Compared with withdrawal group, level of nNOS and iNOS protein in spinal cord in nNOS group and iNOS group were significantly lower.

CONCLUSIONIt is suggested that nNOS and iNOS in the spinal cord may contribute to naloxone-precipitated withdrawal in rats and may play different roles in the above-mentioned effect.

Animals ; Guanidines ; pharmacology ; Indazoles ; pharmacology ; Male ; Morphine Dependence ; metabolism ; Naloxone ; pharmacology ; Nitric Oxide Synthase Type I ; antagonists & inhibitors ; metabolism ; Nitric Oxide Synthase Type II ; antagonists & inhibitors ; metabolism ; Rats ; Rats, Sprague-Dawley ; Spinal Cord ; drug effects ; metabolism ; Substance Withdrawal Syndrome ; metabolism

AIMTo get some novel potent compounds with NOS inhibitory activity, a series of new compounds of isothioureas derived from 1,2,3,4-tetrahydroisoquinoline were synthesized.

METHODS1,2, 3,4-Tetrahydroisoquinol-2-yl was introduced into the structure of isothioureas, the NOS inhibitory activity of the new compounds synthesized were measured.

RESULTS AND CONCLUSIONTwenty-two isothiourea derivatives of [alkyl(or aryl) imino] (1,2,3,4-tetrahydroisoquinol-2-yl) methyl alkyl thioethers (I) and S-alkyl-1-phenyl-3-[4-(1,2,3,4-tetrahydroisoquinol-2-yl) methane] phenyl isothioureas (II) were synthesized from thioureas by S-alkylation with alkyl halides, and their structures were identified by IR, 1H NMR, MS and elemental analysis. The preliminary biological test showed that the part of type I (1-9 and 1-13) had higher NOS inhibitory activity than that the control aminoguanidine (AG), but the type II had weak ability to inhibit NOS.

Molecular Structure ; Nitric Oxide Synthase ; antagonists & inhibitors ; metabolism ; Stereoisomerism ; Tetrahydroisoquinolines ; chemistry ; Thiourea ; analogs & derivatives ; chemical synthesis ; chemistry ; pharmacology

Brain hypoxia-ischemia has been considered as critical factors in many human central nervous system diseases, including stroke and neonatal hypoxic-ischemic encephalopathy. In brain hypoxia-ischemia processes, inducible NO synthase (iNOS) is induced to produce excessive nitric oxide (NO) which leads to cascade reactions of inflammation and neuronal death, deteriorating primary brain injury. Inhibiting iNOS expression has opened new perspectives in the treatment of brain hypoxia-ischemia because iNOS inhibitor has been shown as a potent therapeutic agent. This reviews focus on recent research achievements regarding the relationship between iNOS and ischemic-hypoxic brain damage and the perspective of using iNOS inhibitors as therapeutic strategies for brain ischemic-hypoxic brain damage.
Animals ; Humans ; Hypoxia-Ischemia, Brain ; drug therapy ; metabolism ; Nitric Oxide Synthase Type II ; antagonists & inhibitors ; genetics ; physiology