nitroarginine and Brain-Injuries

To evaluate the effect of NG-nitro-L-arginine (L-NA) on inflammatory factor and neuronal apoptosis after focal cerebral ischemic injury in rats and the possible mechanism of protective effect of L-NA against cerebral ischemic injury.. Thirty male SD rats weighing 250-280 g were randomly divided into three groups (n=10): (1) Sham operated group (SH), (2) Ischemic group (IS), (3) L-NA group. In L-NA group L-NA 20 mg/kg was given intraperitoneally twice a day for 3 consecutive days. In IS group normal saline was given instead of L-NA. Focal cerebral ischemia was produced by middle cerebral artery occlusion (MCAO) for 12 h. A nylon thread with rounded tip which was inserted into left internal carotid artery cranially until resistance was felt. The distance from bifurcation of common carotid artery to the tip of the thread was about 18-19 mm. Focal cerebral ischemia was confirmed by left Horner's syndrome and right side hemiplegia. In SH group the carotid artery was exposed but no thread was inserted. The expression of TNF-alpha was determined by immunochemistry and the content of IL-1beta was measured by radio immunity. The Bcl-2 and Bax protein expression were detected by flow cytometry.. The expression of TNF-alpha and the content of IL-1 beta were markedly increased after MCAO. Significantly increased DNA fragmentation indication of apoptosis was detected after MCAO. The expression of TNF-alpha and the content of IL-1 beta was significantly lower in L-NA group than in IS group. The percentage of apoptosis cells and expression of Bax protein were markedly lower in L-NA group than in IS group but still significantly higher than in SH group. The expression of Bcl-2 protein was markedly higher in L-NA group than in IS group. There was no significant difference in the expression of Bcl-2 protein between IS and SH group.. L-NA could inhibit the increase in the expression of TNF-alpha and the content of IL-1beta, and protect neurons from apoptosis induced by focal cerebral ischemia through increasing the Bcl-2 protein expression and inhibiting the Bax protein expression.

Topics: Animals; Apoptosis; bcl-2-Associated X Protein; Brain Injuries; Brain Ischemia; Interleukin-1beta; Male; Nitroarginine; Proto-Oncogene Proteins c-bcl-2; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

We have investigated the role of nitric oxide (NO) as mediator of the secondary growth of a traumatic cortical necrosis. For this purpose, a highly standardized focal lesion of the brain was induced in 46 Sprague-Dawley rats by cold injury. Twenty-four hours later--the timepoint of maximal lesion spread--the animals were sacrificed and brains were removed for histomorphometry of the maximal necrosis area and volume. The animals were divided into five experimental groups. Group I received the NO donor L-arginine as i.v. bolus 10 min prior to trauma (300 mg/kg body weight; n = 10) and a second bolus of the same dosage intraperitoneally 1 h after trauma. Group II (n = 10)--serving as control of group I--was infused with an i.v. bolus of 1 mL/kg isotonic saline 10 min prior to and a subsequent bolus i.p. 1 h after trauma. Group III (n = 8) received 100 mg/kg b.w. of the inducible NOS (iNOS) inhibitor aminoguanidine (AG) 1 h before and 8 h after trauma by intraperitoneal route. Group IV was administered with the nitric oxide synthase (NOS) inhibitor N(G)-nitro-L-arginine (L-NNA; 100 mg/kg b.w., i.p.; n = 8); group V--the controls of group III and IV--was administered with isotonic saline (1 mL/kg b.w. i.p.; n = 10) 1 h before and 8 h after trauma. In the control group with i.v./i.p. sham treatment (II), the focal lesion led to a cortical necrosis with a maximum area of 3.1 +/- 0.3 mm2 and a lesion volume of 5.7 +/- 0.5 mm3 at 24 h after trauma. In animals with administration of L-arginine, the focal lesion had a maximum area of 3.1 +/- 0.3 mm2 and a volume of 5.3 +/- 0.5 mm3. Hence, the NO donor did not affect the secondary growth of necrosis. Animals with i.p. sham treatment (group V) had a maximal lesion area of 3.6 +/- 0.2 mm2 and lesion volume of 6.2 +/- 0.4 mm3. Administration of aminoguanidine afforded significant attenuation of the lesion growth. Accordingly, the maximal area of necrosis spread only to 2.8 +/- 0.2 mm2 with a volume of 4.5 +/- 0.5 mm3, respectively, at 24 h after trauma (p < 0.01 vs group V). On the other hand, administration of L-NNA did not influence the maximal lesion area (3.7 +/- 0.2 mm2) or lesion volume (6.5 +/- 0.5 mm3) evolving at 24 h after trauma. Thus, neither the enhancement of the formation of NO by L-arginine nor gross inhibition of the synthesis of NO by L-NNA did affect the secondary spread of the necrosis from a focal trauma. The marked attenuation of the posttraumatic necrosis growth by the iNOS inhibitor aminoguanidin

Topics: Animals; Arginine; Brain; Brain Injuries; Cold Temperature; Enzyme Inhibitors; Guanidines; Male; Necrosis; Nitric Oxide; Nitric Oxide Donors; Nitric Oxide Synthase; Nitric Oxide Synthase Type II; Nitroarginine; Rats; Rats, Sprague-Dawley; Time Factors

We investigated the role of nitric oxide (NO) in the vascular response to high extraluminal K(+)-concentrations in the in vitro model of isolated rat middle cerebral arteries (MCA). Under control conditions, rat MCA dilated at 20, 30, 40 and 60 mM K(+). At 80 mM K(+), a slight vasoconstriction occurred. The unspecific NO synthase (NOS)-inhibitor L(omega)-nitro-L-arginine (L-NNA) increased the resting tone at 3 mM K(+) by 31+/-5% (P<0.01). While the vasodilatative effect of 20 mM K(+) was unaffected by L-NNA, NOS-inhibition resulted in vasoconstriction at > or = 40 mM K(+) (P<0.01). In presence of L-NNA, the basal vessel diameter was restored by either the NO-donor S-nitroso-N-acetylpenicillamine (SNAP) or the cell-permeable guanosine-3',5'-cyclic monophosphate (cGMP) analogue 8-Br-cGMP. Co-application of L-NNA with either SNAP or 8-Br-cGMP resulted in partial restitution of the vasodilatative effect of 40 mM K(+), respectively. In presence of the soluble guanylyl cyclase inhibitor 1 H-[l,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), the vascular response to 40 mM K(+) was abolished. Our findings together with findings from the literature indicate a modulator role of NO at K(+) > or = 40 mM K(+), involving a cGMP-dependent mechanism.

Topics: Animals; Brain Injuries; Cerebrovascular Circulation; Cyclic GMP; Enzyme Inhibitors; Extracellular Space; Male; Middle Cerebral Artery; Models, Biological; Nitric Oxide; Nitric Oxide Synthase; Nitroarginine; Organ Culture Techniques; Oxadiazoles; Penicillamine; Potassium; Potassium Channels; Quinoxalines; Rats; Rats, Wistar; S-Nitroso-N-Acetylpenicillamine; Vasodilation

Overstimulation of N-methyl-D-aspartate (NMDA) receptors is felt to precipitate the neuronal damage following traumatic brain injury (TBI). NMDA receptor-mediated, glutamate-induced excitotoxicity is thought to be mediated via nitric oxide (NO) formed by neuronal nitric oxide synthase (nNOS). The present study examined the mRNA and protein levels of nNOS in the ipsilateral and contralateral cortex of rats as a function of time (5 minutes to 1 week) after controlled cortical impact (CCI) brain injury. Sham-operated rats served as controls. TBI resulted in a significant increase in the levels of nNOS mRNA (1.5- to 2.8-fold, p < .05) between 2 and 4 hours after the injury. There was also a significant increase in the levels of nNOS protein (by 55% to 90%, p < .05) and binding densities of the nNOS-specific ligand L-[3H]nitroarginine (L-[3H]NOARG) (by 35% to 59%, p < .05) between 2 and 12 hours after the injury. Increased nNOS expression and function may contribute to the concomitant excitotoxic neuronal death after TBI.

Topics: Animals; Brain Injuries; Functional Laterality; Gene Expression Regulation, Enzymologic; Male; Nitric Oxide Synthase; Nitric Oxide Synthase Type I; Nitroarginine; Rats; Rats, Sprague-Dawley; Reverse Transcriptase Polymerase Chain Reaction; RNA, Messenger; Transcription, Genetic; Tritium

The present study was designed to investigate the effect of fluid percussion brain injury (FPI) on vasopressin-induced pial artery vasodilation and the role of superoxide anion generation in those observed effects. In the piglet, it was observed previously the FPI produces pial artery constriction associated with free radical generation. Anesthetized piglets equipped with a closed cranial window were connected to a percussion device consisting of a saline-filled cylindrical reservoir with a metal pendulum. FPI of moderate severity (1.9-2.3 atm) was produced by allowing the pendulum to strike a piston on the cylinder. Vasopressin in physiological and pharmacological concentrations (10 and 1,000 microU/ml) produced vasodilation that was reversed to constriction after FPI (15 +/- 1 vs. -8 +/- 1 and 25 +/- 1 vs. 13 +/- 1% for 10 and 1,000 microU/ml before and after injury, respectively). Vasopressin-induced dilation was associated with increased cerebrospinal fluid guanosine 3', 5'-cyclic monophosphate, and these biochemical changes were blunted by FPI (407 +/- 12 and 720 +/- 28 vs. 4 and 272 +/- 5 fmol/ml for control and 10 microU/ml before and after injury, respectively). In contrast, polyethylene glycol superoxide dismutase (PEG-SOD) and catalase pretreatment 30 min before FPI partially restored vasopressin-induced pial artery dilation (14 +/- 1 vs. 3 +/- 1 and 22 +/- 1 vs. 2 +/- 4% for 10 and 1,000 microU/ml before and after FPI, respectively). Similarly, biochemical changes associated with vasopressin dilation were also partially restored by PEG-SOD and catalase after FPI. These data show that vasopressin is reversed from a dilator to a vasoconstrictor after FPI and suggests the superoxide anion generation contributes to the alteration of vasopressin cerebrovascular effects after injury and that such altered vasopressin cerebrovascular effects contribute to pial vasoconstriction after FPI.

Topics: Animals; Blood Pressure; Brain Injuries; Catalase; Cerebral Arteries; Cyclic GMP; Female; Male; Nitric Oxide Synthase; Nitroarginine; Pia Mater; Polyethylene Glycols; Superoxide Dismutase; Swine; Vasodilation; Vasopressins