Fluorometric assay of nitrite and nitrate in brain tissue after traumatic brain injury and cerebral ischemia

Nitric oxide synthase (NOS) is distributed within the brain, and nitric oxide (NO) is felt to be involved in the pathophysiology of deterioration after head injury and cerebral ischemia. This study determined the levels of the stable end products of NOS (NO_x=nitrite+nitrate) after traumatic brain injury (TBI) and transient cerebral ischemia. A fluorometric assay using nitrate reductase and the NADPH regenerating system was used to quantitate NO_x in ultrafiltered (10-kDa cutoff) cortical and hippocampal extracts after reduction of nitrate. In TBI rats, both the plasma and tissue showed a sharp increase in NO_x levels 5 min after injury. Plasma NO_x returned to control levels by 2 h after injury. Ipsilateral-cortex NO_x levels returned to control levels 6 h after injury and remained constant from 6–24 h. Contralateral-cortex returned near to control levels after 1 h. Hippocampus also followed a similar trend. In gerbils, there was a significant elevation in tissue NO_x levels immediately after 10 min transient cerebral ischemia, which gradually returned to control levels over 24 h reperfusion. This striking burst of NO synthesis immediately after injury is clearly evident whether the injury is head trauma or ischemia, or whether the measurements were performed on tissue or plasma. It is unknown whether endothelial NOS, neuronal NOS, or both caused the elevation of the NO end products seen after the CNS insults.     

Dexamethasone and indomethacin do not affect brain edema following head injury in rats

Head trauma was induced in rats by a weight-drop device, falling over the exposed skull over the left hemisphere. The neurological state of the rats was evaluated by a neurological severity score at 1 h and 18 h post head trauma. At 18 h post head trauma, rats were decapitated and tissue from the vicinity of the injury and from a corresponding area in the contralateral hemisphere was taken for specific gravity (SG) determination using linear gradient columns. Slices were taken from the same sites for incubation in Krebs-Ringer solution, and the concentrations of prostaglandin (PG)E2, 6-keto-PGF1 alpha, and thromboxane B2 accumulated in the medium during 1 h were measured by radioimmunoassay. In one experimental group, rats were pretreated with intraperitoneal dexamethasone sodium phosphate (4 mg/kg) 18 and 2 h before head trauma, and a third dose was given 8 h post head trauma. Another group was treated with intraperitoneal indomethacin (10 mg/kg) 1 h before and 7 h after head trauma. Other groups were treated immediately and 8 h after head trauma with 4, 8, 15, or 30 mg/kg of dexamethasone sodium phosphate. Another group of rats was treated with free dexamethasone (10 mg/kg) right after head trauma and 8 h later. Head trauma induced edema, as expressed by decreased SG, in the left hemisphere of all traumatized rats. Neither treatment protocol affected the neurological severity score of the injured rats or the SG of the contused hemisphere. PG synthesis, on the other hand, was significantly reduced following indomethacin or free dexamethasone, both in sham and traumatized rats, but not in dexamethasone sodium phosphate-treated rats. We conclude that pretreatment with indomethacin, dexamethasone sodium phosphate, or dexamethasone, used in the present protocols, does not affect posttraumatic cerebral edema. Thus, the role of PGs as mediators of edema formation remains unclear.     

实验性脑积水幼鼠脑脊液中一氧化氮及谷氨酸浓度的变化

目的探讨实验性脑积水幼鼠脑脊液中一氧化氮（NO）和谷氨酸（Glu）浓度的动态变化。方法SD幼鼠40只,随机平分为A、B、C实验组和对照组共4组,用显微外科技术向枕大池内注入25%白陶土混悬液,分别在注射后第2（A组）、3（B组）、4周（C组）后行MRI检测,鉴定脑积水形成情况;之后24h内取脑脊液,用硝酸还原酶法测NO浓度、高效液相色谱仪检测Glu浓度。对照组幼鼠于枕大池内注入生理盐水,用同样方法检测。结果实验组21只幼鼠成功诱发脑积水。与对照组相比,实验组脑脊液中NO和Glu浓度显著增加（P〈0.01）。结论脑脊液中高水平的NO和Glu可能参与了实验性脑积水幼鼠的病理损伤过程。     

Effect of Zen Meditation on serum nitric oxide activity and lipid peroxidation

This study was designed to investigate the effect of Zen Meditation on serum nitric oxide activity (NO) and oxidative stress (lipid peroxidation). The experimental group included 20 subjects who had practiced the Zen Meditation program in Meditation Center located in Seoul, South Korea. The control group included 20 subjects who did not practice any formal stress management technique and were age and sex matched with experimental group. To provide an assessment of nitric oxide production, the serum level of nitrate/nitrite was determined using the Griess reagent. Malondialdehyde (MDA) concentration was measured as a convenient index of lipid peroxidation by thiobarbituric acid (TBA) method. Meditation group showed a significant higher level of serum nitrate+nitrite concentration and a significant reduced level of serum malondialdehyde (MDA) than control group. A comprehensive randomized controlled trial should be performed to prove the causal relationship between meditation and level of nitric oxide or oxidative stress in reducing cardiovascular risk factors.     

Possible role of nitric oxide in postoperative ileus: a comparative study

In the present study, the possible involvement of nitric oxide (NO) in the pathogenesis of postoperative ileus was investigated indirectly by measuring nitrate, a stabile metabolite of NO. Plasma levels and 24-h urinary excretion of nitrate and nitrite were determined in the peri-operative period in three different groups of patients undergoing surgery: group 1 (LT, n=11) underwent a laparotomy, group 2 (LS, n=12) underwent a laparoscopic procedure, whereas group 3 underwent an extra-abdominal procedure (EA, n=9). Duration of postoperative ileus was assessed clinically using first occurrence of flatus and defaecation as the end of the period of ileus. Postoperative ileus lasted significantly longer in the LT group (first flatus after 3.0 [3.0-4.0] days) compared with the LS (1.0 [1.0-2.0] days) and EA (1.0 [1.0-3.0] days) groups. Urinary nitrate excretion increased significantly in the LT and EA groups during the first 24 h after surgery (from 797.0 [214.0-810.0] and 551.5 [438.3-1215.8] to 2079.0 [889.0-4644.0] and 1102.5 [315.3-1238. 0] micromol/24 h, median [IQR]), but normalized before the end of postoperative ileus. Plasma levels of nitrate were unchanged after surgery, whereas CRP levels were significantly increased in all groups (LT > LS=EA). In the first 24 h following surgery, urinary nitrate excretion is increased, suggesting increased endogenous synthesis of NO postoperatively. As no correlation was found between urinary nitrate excretion and duration of postoperative ileus, we conclude that assessment of nitrate has no value in predicting clinical outcome after surgery.     

Antioxidant properties of propofol and erythropoietin after closed head injury in rats

Reactive oxygen species play a role during brain injury due to closed head trauma. Enzymatic or nonenzymatic antioxidants may protect brain tissue against oxidative damage. The present study was performed to assess the changes of endogenous indices of oxidative stress in serum from rats subjected to head trauma and whether treatment with propofol and/or erythropoietin (EPO) modifies the levels of endogenous indices of oxidative stress. For these purposes, female Wistar Albino rats were divided into five groups: non-traumatic sham group, trauma performed control, trauma with propofol (i.p.), trauma with EPO (i.p.) and trauma with propofol and EPO performed study groups. At the end of the experimental procedure, blood was taken by cardiac puncture to determine superoxide dismutase (SOD) and xanthine oxidase (XO) activities as well as malondialdehyde (MDA) and nitric oxide (NO) levels in serum. Serum MDA level of control traumatic brain injury (TBI) group was significantly higher than sham operation group (p<0.012). Serum MDA levels in propofol, EPO and propofol+EPO groups were found to be decreased in comparison with control group (p<0.039, p<0.030 and p<0.018, respectively). Serum NO level was found to be increased in TBI group, but difference was not statistically significant when compared to sham-operated group (p=0.092). Propofol, EPO and propofol+EPO administration efficiently reduced serum NO levels to reach sham-operated group (p<0.002, p<0.001 and p<0.015, respectively). These results suggested that acute administration of both propofol and EPO altered the indices of oxidative stress similarly against brain injury due to trauma.     

早期激素干预对急性一氧化碳中毒大鼠迟发性脑病的预防作用

目的观察早期激素干预对急性一氧化碳中毒大鼠迟发性脑病（DEACMP）的预防作用。方法将132只雄性Wistar大鼠随机分成3个实验组：CO中毒组（COP组）、CO中毒＋地塞米松10 mg/kg组（DSMS-10组）和CO中毒＋地塞米松30 mg/kg组（DSMS-30组）,每组40只。另设健康对照组（NC组）,12只。实验组按150 ml/kg腹腔内注射CO制备急性一氧化碳中毒动物模型,健康对照组大鼠注射等体积的空气。在中毒后30 min内DSMS-10组腹腔内注射地塞米松剂量为10 mg/kg/d,共7 d;DSMS-30组腹腔内注射地塞米松剂量为30 mg/kg/d,共7 d;NC组和COP组则注射等剂量生理盐水。监测中毒后90 min、7 d、14 d、21 d各组大鼠血清中髓鞘碱性蛋白（MBP）的含量,并在上述各时间点处死大鼠取脑组织,行HE及MBP免疫组化染色。采用Morris水迷宫实验评估动物的智力状态。结果 Morris水迷宫实验结果显示,COP组中有8只大鼠被判定为迟发性脑病;DSMS-10组中有6只被判定为迟发性脑病;而DSMS-30组和对照组未出现迟发性脑病。COP组大鼠血清中MBP含量增高最显著,DSMS-10组也有增高,DSMS-30组接近正常。差异在中毒后90 min、7 d最明显。病理学检查显示COP组中发生迟发性脑病的大鼠在中毒90 min~21 d后脑海马、皮质下出现神经元损伤、髓鞘碱性蛋白脱失等病理改变,上述病理改变在各实验组中均可观察到,但以COP组大鼠病变程度最重,DSMS-30组最轻。结论10 mg/kg地塞米松可降低急性一氧化碳中毒大鼠迟发性脑病的发生率。30 mg/kg地塞米松则可避免迟发性脑病的发生。     

选择性一氧化氮合成酶抑制剂对脑组织保护作用研究

目的：探讨创伤性脑损伤后脑组织中一氧化氮（NO）含量变化与脑组织病理及超微结构变化之间的关系，及选择性一氧化氮合成酶抑制剂（iNOS）1400W(N-[3-(aminomethyl)benzyl]acetamidine)对脑组织的保护作用。方法：114只大鼠随机分成正常组、假手术组、生理盐水治疗组和1400W治疗组，建立大鼠自由落体脑外伤模型，伤后18h开始分别给予生理盐水和1400W腹腔内注射，每8h一次。测定各组不同时期脑组织NO含量，同时观察脑组织病理及超微结构的改变，将结果进行比较。结果：生理盐水治疗组NO含量于伤后6h开始升高，48h达到高峰，以后逐渐下降。1400W治疗组NO含量降低，与生理盐水治疗组结果比较有统计学意义，72h后逐步恢复正常。生理盐水治疗组组织病理学检查和超微结构检查结果与NO改变同步，1400W治疗组较生理盐水治疗组明显改善。结论：NO对脑外伤后继发性损伤起着重要作用，1400W对脑外伤后脑组织有显的保护作用。     

Production of nitrite by primary rat astrocytes in response to pneumococci

Recent studies using a rat model of pneumococcal meningitis have shown that nitric oxide synthase (NOS) inhibitors greatly attenuated microvascular changes and brain edema formation. The site of NO production during bacterial meningitis is unknown. In this study we tested whether primary astrocyte cultures from neonatal rat cortex can be induced to release NO upon stimulation with pneumococci. NO production was assessed by measuring nitrite in the cell culture supernatant using the Griess reaction. Stimulation with heat-killed unencapsulated pneumococci (HKP) increased nitrite concentrations in astrocyte culture supernatants in a dose-dependent fashion. Administration of AT-nitro-L-arginine (L-NA), aminoguanidine, L-canavanine, cycloheximide, and dexamethasone prevented the increase in nitrite concentrations. Addition of L-arginine, but not of o-arginine, partially reversed the inhibitory effect of L-NA. Administration of SOD increased nitrite accumulation. Moreover, at 72 h after stimulation with heat-killed pneumococci (10⁷ cfu/ml) astrocytes showed an inducible NOS-like immunoreactivity. Accumulation of nitrite was also observed when rat cerebellar neurons and microglia were stimulated with HKP, whereas there was only a slight increase of nitrite in media of rat C6 glioma cells, but no increase of nitrite when the human glioblastoma cell line LN-229 was stimulated with HKP. There was a stronger increase in nitrite levels when astrocytes from Lewis rats were used compared to that from Wistar rats. In conclusion, our study indicates that astrocytes, neurons and microglia are inducible for NO production upon stimulation with pneumococci.     

大鼠实验性脑损伤血浆中NO及NOS的动态变化研究

目的 测定实验性脑损伤后血浆中一氧化氮含量、一氧化氮合酶活性,研究其与脑水肿之间的关系.方法 大鼠随机分组,用硝酸还原酶法测定血清中NO含量、NOS活性,及测定脑组织含水量.并行还原型辅酶Ⅱ依赖性黄递酶(NADPⅡ-d)组化染色检测皮层及脑底NOS阳性细胞.结果 (1)TBI后血浆内NO含量、NOS活力即有升高,与对照组比较有明显差异(P＜0.05).(2)脑组织含水量在外伤后升高,与对照组比较有明显差异(P＜0.05).与血浆中NO含量、NOS活力变化趋势一致.(3) NADPⅡ-d组化染色显示TBI皮层NOS阳性细胞明显多于正常对照组,伤灶脑底也出现了染色块及浓染的细胞群与阳性纤维束.结论 大鼠TBI后NO含量、NOS活性的升高,与脑水肿的发生有关.     

大鼠颅脑外伤致多器官功能障碍综合征模型的建立

目的建立符合临床实际、简便易行的颅脑外伤致多器官功能障碍综合征（MODS）模型。方法采用改进自由落体法建立颅脑外伤致MODS模型,48只Wistar大鼠随机分为正常对照组、假手术组、颅脑外伤不同时间后6个亚组（4,12,24,36,48,72h组）,记录各时相点大鼠颅脑外伤后的症状、体征,检测外周血WBC、肝肾功能、心肌酶学改变。光镜下观察肺、小肠、肝和肾组织病理变化,依据全身炎症反应综合征（SIRS）和MODS的诊断标准判断SIRS和MODS的发生率。结果（1）假手术组与正常对照组相比,其呼吸、心率、体温及外周血WBC、ALT、AST、BUN、Cr、CK的差异无显著意义（P〉0.05）;颅脑外伤组的上述各项指标均高于正常对照组、假手术组（P〈0.01）,并且在24～36h变化最明显;（2）大鼠颅脑外伤后各时相点各脏器组织均有不同程度的炎性损害,颅脑外伤组在24～36h时相点的脏器病理变化最显著,在48h稍有减轻,72h时相点仍可见炎性损害;（3）颅脑外伤组SIRS的发生率为100%;MODS发生率为69.4%,病死率为38.9%。结论（1）采用大鼠改良自由落体法可成功建立颅脑外伤致MODS的实验动物模型;（2）颅脑外伤后存在重要脏器的炎性改变及SIRS,提示SIRS是颅脑外伤致MODS的病理学基础。     

Serum and urine nitrate and nitrite are not reliable indicators of intrathecal nitric oxide production in acute brain injury

This study examined the correlation between nitric oxide (NO) metabolites in the three major body fluid compartments and assessed performance of newly described vanadium-based assay for simultaneous detection of nitrite and nitrate (NO(x)) in human samples. Vanadium reduces nitrate to nitrite, which can be measured after a colorimetric reaction with Griess reagents.Cisternal cerebro spinal fluid (CSF), serum and urine samples from 10 patients with acute brain injury (ABI) were compared to control subjects. Significantly higher CSF NO(x) levels were found in brain injury patients compared to control patients (19.7+/-13.7 vs. 6.5+/-2.3 microM; p=0.01), which persisted for 10-day period of observation. The serum and urine levels of NO(x) on admission were not statistically different (42.8+/-28.2 microM; 584.1+/-337.8 micromol/g Cr, respectively) from controls (36.8+/-14.8 microM; 819.7+/-356.0 micromol/g Cr), but tended to decrease during the disease course reaching the lowest level on day 6 (serum: 19.3+/-8.4 microM, urine: 300.4+/-111.9 micromol/g Cr). CSF levels of NO(x) correlated moderately with those in serum (p=0.001, R=0.5). Serum NO(x) concentrations correlated weakly with urine levels (p=0.04, R=0.3). There was no significant correlation between CSF NO(x) and urine NO(x) levels.In conclusion, patients suffering brain injury had increased NO(x) concentrations in CSF, which remained independent from other body fluid compartments. Serum and urinary NO(x) levels cannot be used as a reliable index to assess intrathecal NO production.     

Nitric oxide involvement in estrous cycle-dependent changes of the behavioral responses of female rats in the elevated plus-maze test

Nitric oxide (NO)/cGMP pathway is known as a mediator in anxiety modulation. In this study, we assessed the involvement of NO pathway in the estrous cycle-related changes of anxiety level in rat. By using elevated plus-maze test, we studied the changes of serum nitrate and nitrite (NO(x)) levels in comparison to the estrous cycle-dependent changes of anxiety state. Then, we tested the effects of nitric oxide synthase (NOS) inhibitor, L-NAME (10, 60mg/kg, i.p.), and the NO precursor, l-arginine (100mg/kg, i.p.) on anxiety modulatory properties of exogenous ovarian hormones in ovariectomized (OVX) rats. Compared with other cycle phases and with OVX rats, cycling rats spent more time in open arms and had lower levels of serum NO(x) levels during metestrous while they spent less time in open arms and had lower levels of serum NO(x) levels during proestrous. In OVX rats, L-NAME (60mg/kg, i.p.) exerted anxiolytic effect while l-arginine showed no effect. In comparison with corn oil-treated controls, estradiol benzoate (10microg/kg, subcutaneously (s.c.)) significantly increased the serum NO(x) level and exerted anxiogenic effect, which was dose-dependently inhibited by L-NAME but was not changed by l-arginine. In contrast, progesterone (25mg/kg, s.c.) significantly decreased the serum NO(x) level and exerted anxiolytic effect, which was abolished by l-arginine but was not affected by L-NAME. These findings suggest that NO system might be involved in the estrous cycle-related changes of anxiety level, probably by mediating the effect of ovarian sex hormones.     

Serum nitrite and nitrate levels in epileptic children using valproic acid or carbamazepine

In experimental epilepsy studies, nitric oxide was found to act as both proconvulsant and anticonvulsant. The objective of this study was to investigate the effects of valproic acid and carbamazepine on serum levels of nitrite and nitrate, which are the metabolites of nitric oxide. To achieve this goal, serum nitrite and nitrate levels were determined in active epileptic 34 children using valproic acid and 23 children using carbamazepine and in non-active epileptic 38 children (control group) not using any antiepileptic drug. In the valproic acid group serum nitrite and nitrate levels were 2.66 +/- 2.11 micromol/l and 69.35 +/- 23.20 micromol/l, 1.89 +/- 1.01 micromol/l and 49.39 +/- 10.61 micromol/l in the carbamazepine group, and 1.22 +/- 0.55 micromol/l, 29.53 +/- 10.05 micromol in the control group, respectively. Nitrite and nitrate levels were significantly high in both valproic acid and carbamazepine groups compared to the control group (P < 0.01). When valproic acid and carbamazepine groups were compared to each other, level of nitrate was found statistically higher in the valproic acid group in relation to the carbamazepine group (P < 0.01), however, there was no statistically significant difference in the levels of nitrite (P > 0.05). No relation could be found between serum drug levels and nitrite and nitrate levels. According to these results, it can be suggested that valproic acid and carbamazepine might have antiepileptic effects through nitric oxide.     

Cerebrospinal fluid nitric oxide metabolites in painful diseases

To elucidate the involvement of NO in pain transmission in humans, we measured NO metabolites (nitrite/nitrate) in the CSF of patients with painful diseases using an NO analyzer based on the Griess method. The nitrite/nitrate levels in patients with degenerative lumbar disease (DLD), but not those with fracture or appendicitis, were significantly higher than those in an age-matched control group. The duration of pain in the DLD group was much longer than that in the fracture or appendicitis group. The nitrite/nitrate levels in the middle-aged and elderly DLD patients depended on the duration of pain. These data probably suggest that the duration of pain is critical for the elevation in nitrite/nitrate levels.     

Correlations between event-related potential components and nitric oxide in maximal anaerobic exercise among sportsmen trained at various levels

Physical exercise has influence on all organs except its effects on the central nervous system have not been fully elucidated. This study attempts to determine whether the degree of training could affect the response to physical stress by comparing the three groups of males in different levels of the physical fitness. Serum samples from high (n = 11), moderate (n = 10), and low physical activity sportsmen (n = 10) were collected to determine nitrite/nitrate levels before and after carrying out an anaerobic maximal exercise test. An "oddball paradigm" of auditory stimuli was used to evoke the N200 and P300 before and after the exercise. The amplitude of the N200 decreased significantly after anaerobic maximal exercise compared to the values of the recorded pre-exercise at Fz area in high physical activity group. There was a negative correlation between event-related potentials component and both nitrite/nitrate serum level changes and the heart rate changes in low physical activity subjects. However, in high and moderate physical activity groups, these relationships were positive.     

Is there a role for nitric oxide activity in cervicogenic headache?

Cervicogenic headache (CEH) is a unilateral headache that can be provoked by neck movement, awkward head positions or pressure on tender points in the neck. The mechanisms underlying the stimulation of pain in CEH are not clearly known. In this study, we measured serum nitrate and nitrite levels as an index of nitric oxide (NO) activity in 15 patients with CEH during headache and headache-free periods and in 15 healthy controls. Total nitrate+nitrite levels were found to be higher in CEH patients during headache periods than in healthy controls (20.7+/-3.8 micromol/l vs 14.4+/-3.6 micromol/l, p<0.001), but not in CEH patients during headache-free periods (16.1+/-2.2 micromol/l) compared with the controls (p>0.05). In the patients with CEH, serum total nitrate+nitrite levels were found to be higher during headache periods than during headache-free periods (p=0.001). It can thus be hypothesized that the changes observed are a cause of the attack rather than a consequence of the disease process.     

Does pinealectomy affect the recovery rate after spinal cord injury?

Previous reports documented demonstrated that melatonin, a free radical scavenger, is important in protecting against oxidative stress-induced tissue damage after spinal cord injury (SCI). This study was undertaken to investigate the effects of pinealectomy (PX) and administration of exogenous melatonin after SCI in rats. These animals were randomized into six groups, each having 12 rats. Group 1 underwent laminectomy alone. Group 2 underwent laminectomy followed by SCI and received no medication. Group 3 underwent laminectomy followed by SCI and received melatonin. Group 4 underwent PX and laminectomy alone. Group 5 underwent PX and laminectomy followed by SCI and received no medication. Group 6 underwent PX and laminectomy followed by SCI and received melatonin. Melatonin (100 mg/kg) was given intraperitoneally immediately after trauma to the rats in the groups 3 and 6. PX caused a significant increase in the malondialdehyde (MDA), nitrite oxide (NO), glutathione (GSH), xanthine oxidase (XO) levels and decrease in GSH levels as compared with the control group. Trauma to the spinal cord results in significantly higher oxidative stress. Melatonin administration significantly reduced MDA, XO and NO levels, and increased GSH levels in the spinal cord after trauma. Exogenous melatonin treatment after trauma attenuated tissue lesion area and accelerated motor recovery rate. These findings suggest that reduction in endogenous melatonin after PX makes the rats more vulnerable to trauma and exogenous melatonin administration has an important neuroprotective effect on the level of the spinal cord.     

Effect of exercise training on oxidized LDL-mediated platelet function in rats

This study investigates how exercise training affects Oxidized LDL (Ox-LDL) mediated-platelet activation. Five-week-old male Wistar rats were assigned to either control or trained groups. Trained rats were treadmill-trained for 10 weeks after familiarization. The following measurements were taken in both control and trained groups: Ox-LDL-mediated platelet aggregability and [Ca2+]i, plasma and platelet-derived nitric oxide (NO) metabolite (nitrite plus nitrate) levels, and antiaggregating activity of NO derived from endothelial cells. Based on those measurements, major findings in this study can be summarized as follows: 1) the trained group had a higher plasma -NO metabolite level than the control group; 2) the trained group had a lower platelet aggregability and [Ca2+]i elevation and a higher platelet derived-NO metabolite level than the control group; 3) the trained group had lower Ox-LDL-potentiated platelet aggregability and [Ca2+]i elevation and Ox-LDL-attenuated NO metabolite in platelet than the control group; 4) treating the platelet with L-arginine inhibited Ox-LDL-potentiated platelet activation in both control and trained groups; 5) Ox-LDL enhances platelet aggregation directly although impairing NO bioactivity but not guanylate cyclase activity in both control and trained groups. Results in this study demonstrate that exercise training decreases Ox-LDL-potentiated platelet activation most likely by enhancing platelet-derived NO release.     

戊四氮致痫大鼠脑脊液神经元特异性烯醇化酶的水平测定

目的通过测定戊四氮致痫大鼠脑脊液中的神经元特异性烯醇化酶(NSE)水平的变化,探讨痫性发作与脑损伤之间的关系。方法110只Wistar大鼠分为实验组和对照组。实验组给予戊四氮(PIZ)腹腔注射。根据痫性发作的强度分为轻度组和重度组。用酶联免疫吸附法(ELISA)测定不同痫性发作强度、不同时间点大鼠脑脊液中NSE水平的变化,并与对照组进行对比。结果重度组脑脊液NSE水平在1h、2h、4h、6h均显著高于轻度组和对照组(P<0.01);轻度组脑脊液NSE含量在1h高于对照组(P<0.05),在2h、4h、6h显著高于轻度组;脑脊液NSE水平在痫性发作后1h迅速升高。4h达到高峰,24h恢复到正常水平。结论痫性发作可对大鼠神经细胞造成明显的损害。损害的程度与痫性发作的程度有关。痫性发作后4h可能是进行早期干预、防止脑细胞损伤的时间窗。