大鼠脊髓损伤后一氧化氮合酶基因表达的变化

目的　探讨大鼠脊髓损伤后3种类型一氧化氮合酶（NOS）mRNA表达的变化规律。方法　成年SD大鼠36只,随机分为种类6组,每组6只大鼠。建立大鼠脊髓压迫伤模型,以逆转录-聚合酶链反应（RT-PCR）法测定伤段脊髓组织神经型（nNOS）、诱导型（iNOS）及内皮型（eNOS）一氧化氮合酶的mRNA表达情况。结果　脊髓压迫伤后nNOSmRNA及NOSRNA表达增强,伤后6h达到高峰0.633±0.012、1.236±0.207;iNOSmRNA表达亦增高,但在伤后24h才达到高峰1.043±0.049。结论　脊髓损伤后NOSmRNA的表达增强,但不同类型的NOSmRNA变化规律不同,增强或抑制不同NOSmRNA的表达可能减轻脊髓继发性损伤。     

The role of constitutive nitric oxide synthase in pathogenesis of secondary lesion after spinal cord injury. Preliminary results

BACKGROUND: Secondary lesion (SL) is an early phenomenon of cellular death following spinal cord injury (SCI). Nitric oxide (NO) could be involved in its pathogenesis. NO is a gaseous metabolite produced by 2 constitutive isoforms of NO synthase (cNOS), constantly active, and by 1 inducible isoform (iNOS), synthesized during inflammation and able to produce large amount of NO. High concentrated NO is toxic for cells; therefore, NO concentration is strictly and finely regulated. We suppose that major inhibitory effect on the iNOS expression is represented by the same physiological concentration of NO, synthesized by cNOS. The aim of this study is to assess the role of the 2 cNOS in pathogenesis of SL after SCI in rat. METHODS: A dorsal SCI has been performed on rats (n=5) by a vascular clip (50 g/mm(2) for 15"). Fifteen minutes after trauma, activity of nNOS and eNOS has been measured (U/mg) in the cervical, dorsal and lumbar segments of spinal cord. Uninjured rats (n=5) served as control group. m-RNA for iNOS in untreated rats (n=2) has been also investigated by Northern blotting. RESULTS: In injured rats nNOS activity has shown a reduction in dorsal and lumbar segments, compared to the control group. eNOS activity, highly variable in the control group, has not been detectable in injured spinal cord. i-NOS mRNA has not been found in spinal cord of uninjured rats. CONCLUSIONS: These results would be in line with our hypothesis and provide the bases for other investigations. New therapeutic strategies for SL prevention, based on the modulation of cNOS, will be evaluated.     

大鼠睾丸内一氧化氮合酶的表达

目的 :阐明一氧化氮合酶 (NOS)在睾丸内的表达 ,探讨一氧化氮 (NO)在睾丸生殖功能中的作用。　方法 :取雄性SD大鼠睾丸于 4 %多聚甲醛中固定 ,常规石蜡切片。用免疫组化ABC法检测成年大鼠睾丸NOS的表达和定位。　结果 :内皮型NOS(eNOS)、神经型NOS(nNOS)、诱导型NOS(iNOS)在睾丸间质细胞内均有表达 ,精曲小管周围肌样细胞、血管内皮细胞和平滑肌细胞内仅为eNOS免疫反应阳性 ,而血管外膜纤维内仅有nNOS表达。免疫反应物质主要定位于细胞质 ,胞核为阴性。在生精细胞内 3种NOS免疫反应均为阴性。　结论 :3种NOS在睾丸内均有表达 ,不同的NOS分布部位有一定区别     

Creatine diet supplement for spinal cord injury: influences on functional recovery and tissue sparing in rats

Creatine-supplemented diet significantly attenuates cortical damage after traumatic brain injury in rodents. The protective mechanism likely involves maintenance of mitochondrial homeostasis. In the present study, we used two separate contusion spinal cord injury (SCI) instruments--the NYU device and the PSI Infinite Horizon (IH) impactor--to assess the efficacy of creatine-supplemented diets on hind limb functional recovery and tissue sparing in adult rats. Rats were fed control versus 2% creatine-supplemented chow for 4-5 weeks prior to SCI (pre-fed), after which most resumed a control diet while some remained on a 2% creatine diet (pre & post-fed). Following long-term behavioral analysis (BBB), the amount of spared spinal cord tissue among the dietary regimen groups was assessed using stereology. Comparatively, both instruments caused similar amounts of gray matter damage while the NYU device rendered a greater loss of white matter, reflected in more severe hind limb functional deficits than with the IH impactor. Relative to the control fed groups injured with either instrument, none of the creatine fed animals showed improvements in hind limb function or white matter tissue sparing. Although creatine did not attenuate gray matter loss in the NYU cohort, it significantly spared gray matter in the IH cohort with pre-fed and pre & post-fed regimens. Such selective sparing of injured spinal cord gray matter with a dietary supplement yields a promising strategy to promote neuroprotection after SCI. The relationship between the efficacy of creatine and the magnitude of the insults is discussed.     

NOS Isoforms in Adult Human Osteocytes: Multiple Pathways of NO Regulation?

Until now, eNOS has been considered to be the predominant osteocytic nitric oxide synthase (NOS) isoform in bone. We previously studied the distribution of eNOS protein expression in the human femoral neck because of its possible involvement in the response to load. Studies in rat and human fracture callus have shown that nNOS mRNA is expressed sometime after fracture, but no study has yet immunolocalized NOS isoforms in mature adult human bone. In this study, we have examined the distribution of NOS isoforms in iliac osteocytes. Frozen sections (10 m) were cut from transiliac biopsies from 8 female osteoporotic patients (range, 56–80 years) and from 7 female postmortem femoral neck biopsies (range, 65–90 years). Sections were incubated overnight in antiserum for eNOS, nNOS, or iNOS followed by peroxidase/VIP substrate detection. We used eNOS and iNOS antisera directed against the C-terminus. For nNOS, three different antisera were used, two binding to different C-terminal epitopes and one binding to N-terminal epitope. Sections were then incubated in propidium iodide or methyl green to detect all osteocytes. eNOS antibody was able to detect eNOS epitopes in osteocytes. All three nNOS antibodies detected nNOS epitopes in osteocytes, but those directed against the C-terminus had higher detection rates. iNOS was rarely seen. In the iliac crest, the percentage of osteocytes positive for nNOS was higher than that for eNOS (cortical: nNOS 84.04%, eNOS 61.78%, P < 0.05; cancellous: nNOS 82.33%, eNOS 65.21%, P < 0.05). In the femoral neck, the percentage of osteocytes positive for nNOS (60.98%) was also higher than that for eNOS (40.41%), although this difference was not statistically significant. In conclusion, both eNOS and nNOS isoforms are present in osteocytes in the iliac crest and femoral neck.     

大剂量甲基强地松龙对大鼠脊髓损伤后iNOS表达及细胞凋亡的影响

目的：探讨大鼠脊髓损伤后应用大剂量甲基强地松龙(MP)对诱导型一氧化氮合酶(iNOS)表达及细胞凋亡的影响。方法：成年大鼠随机分为脊髓损伤后应用大剂量甲基强的松龙治疗组(A组)和应用生理盐水对照组(B组)，损伤后不同时间点(4h、8h、1d、3d、7d、14d、21d)按Tarlov标准评价大鼠双后肢神经功能恢复情况，然后处死。用HE染色观察损伤脊髓组织病理变化，用免疫组化染色检测iNOS阳性细胞，原位末端标记法(TUNEL法)标记凋亡细胞。结果：HE染色镜检发现脊髓组织病理学改变A组明显轻于B组。A、B两组均发现凋亡细胞及iNOS表达，神经细胞凋亡指数及iNOS表达均为B组＞A组(P＜0．01)。结论：大剂量甲基强的松龙能抑制大鼠脊髓损伤后iNOS表达及细胞凋亡。     

诱导型一氧化氮合酶反义核酸对脊髓损伤后神经功能的影响

目的　观察诱导型一氧化氮合酶反义核酸 (ASODN iNOS)对大鼠脊髓损伤 (SCI)后神经功能恢复的影响。方法　设计并合成ASODN iNOS ,微量注入大鼠蛛网膜下腔后制备成脊髓压迫伤动物模型 ,伤后 6h用逆转录 聚合酶链反应 (RT PCR)检测iNOSmRNA表达变化 ,2 4h后用分光光度法测定组织中一氧化氮 (NO)含量和一氧化氮合酶 (NOS)活性 ,4周后用电生理、动物行为学和病理学等指标评价神经功能的恢复情况。对照组为正常组、损伤对照组和无义核酸对照组 (NSODN)。结果　SCI后组织中存在iNOS的表达 ,应用ASODN iNOS可以抑制相应酶的表达 ,并可以降低组织中的NO含量和NOS活性 ,改善神经传导功能 ,与损伤对照相比差异有显著性 ,NSODN没有上述作用。结论　脊髓损伤后应用iNOS反义核酸可以使伤后神经功能得到改善。     

一氧化氮合酶在大鼠大肠癌细胞中的表达及意义

目的研究一氧化氮合酶(NOS)在大鼠大肠癌发生中的表达情况。方法应用免疫组化技术检测1，2二甲基肼(1，2-DMH)诱导的Wistat大鼠大肠癌模型中内皮型NOS(eNOS)，神经元型NOS(nNOS)和诱生型NOS(iNOS)在正常黏膜和大肠癌中的表达情况。结果eNOS和nNOS在正常黏膜中表达，在大肠癌中不表达；iNOS在正常黏膜中表达率很低(10%)，在大肠癌中高表达(87％)。结论在1，2-DMH诱导的大肠癌模型中，iNOS表达与大肠癌的发生关系密切。     

电针对神经病理性痛大鼠脊髓NO/cGMP信号转导通路的影响

目的 探讨电针对神经病理性痛大鼠脊髓一氧化氮/环鸟苷酸(NO/cGMP)信号转导通路的影响.方法 清洁级雄性SD大鼠48只,体重190～210 g,随机分为3组(n=16):假手术组(S组)仅分离坐骨神经,不结扎;神经病理性痛组(NP组)采用坐骨神经慢性压迫性损伤(CCI)法制备神经病理性痛模型;电针组(E组)于CCI后11～17 d时采用穴位神经刺激仪进行电针刺激,刺激大鼠术侧委中穴与环跳穴,刺激频率2 Hz,波宽0.6 ms,起始电流强度1 mA,每10 min递增1 mA,刺激时间30 min,1次/d.于CCI前(基础状态)、CCI后10、16 d时测定机械痛阈和热痛阈.CCI后10 d时痛阈低于基础痛阈的30%为模型制备成功.CCI后17 d时处死大鼠,取脊髓组织,采用分光光度法测定脊髓总一氧化氮合酶(tNOS)、诱导型一氧化氮合酶(iNOS)和神经元型一氧化氮合酶(nNOS)的活性,免疫组化法测定脊髓背角nNOS和iNOS的表达,采用硝酸还原酶法测定脊髓NO含量,采用放射免疫分析法测定脊髓cGMP含量.结果 与基础值比较,NP组和E组CCI后机械痛阈和热痛阈降低(P＜0.01);与CCI后10 d时比较,E组CCI后16 d时机械痛阈和热痛阈均升高(P＜0.01);与S组比较,NP组机械痛阈和热痛阈降低,脊髓tNOS、nNOS活性、NO和cGMP含量升高,nNOS表达上调,E组机械痛阈和热痛阈降低(P＜0.05或0.01),其余指标差异无统计学意义(P＞0.05);与NP组比较,E组机械痛阈和热痛阈升高,脊髓tNOS和nNOS活性、NO和cGMP含量降低,nNOS表达下调(P＜0.05或0.01).3组脊髓iNOS活性和表达比较差异无统计学意义(P＞0.05).结论 电针减轻大鼠神经病理性痛的机制与抑制脊髓NO/cGMP信号转导通路有关.     

米诺环素对大鼠脊髓损伤后线粒体细胞色素C的释放及神经细胞凋亡的影响

目的：探讨大鼠脊髓损伤后应用米诺环素（minocycline）对线粒体细胞色素C的释放及神经细胞凋亡的影响。方法：成年大鼠脊髓损伤后分为应用米诺环素腹腔注射的治疗组（A组）和应用生理盐水的对照组（B组），于损伤后不同时间点取材，采用流式细胞仪磷脂结合蛋白V，碘化丙啶（AnnexinV／PI）双标检测凋亡细胞，HE染色观察损伤脊髓组织病理变化，免疫组化染色检测胞浆中细胞色素C表达阳性的神经细胞以及BBB运动评分观察术后动物行为学。结果：HE染色镜检发现损伤脊髓组织病理学改变A组明显轻于B组；免疫组化染色A、B两组均发现凋亡的神经细胞以及胞浆中细胞色素C的阳性表达，神经细胞凋亡率及细胞色素C表达的阳性细胞率B组均〉A组（P〈0．01）；术后动物行为学观察显示，与B组比较A组大鼠后肢的运动功能显著增强，后肢反射的恢复较快。BBB运动评分B组明显小于A组（P〈0．05）。结论：米诺环素能有效抑制大鼠脊髓损伤后神经细胞凋亡以及线粒体中细胞色素C的释放，促进神经功能的恢复。     

Nitric oxide synthase and renin–angiotensin gene expression and NOS function in the postnatal renal resistance vasculature

Nitric oxide (NO), produced by nitric oxide synthase (NOS), critically counteracts angiotensin-II-enhanced vascular resistance in the immature kidney, perhaps due to the developmental regulation of NOS expression and function in the postnatal preglomerular resistance vessels (PRV). Our experiments measured the messenger ribonucleic acid (mRNA) gene expression of neuronal NOS (nNOS), endothelial NOS (eNOS), and components of the renin-angiotensin system (renin, AT1 and AT2 receptors), by real-time RT-PCR, as well as NOS enzymatic activity by citrulline assay in PRVs (afferent, interlobular, and arcuate arterioles) obtained from swine ages newborn, 7 and 21 days, and adult. NOS enzymatic activity was upregulated in PRVs immediately after birth but decreased to adult levels with maturation. Neuronal NOS, renin, and AT2 receptor expression in PRVs were upregulated in the newborn and decreased with age to lowest levels in the adult. In contrast, eNOS and AT1 receptor expression were downregulated at birth but increased to the highest levels in the adult. Upregulated NOS enzymatic activity in newborn PRVs supports the critical neonatal role for NO renal vascular vasodilation. Upregulated nNOS gene expression, concomitant with downregulated eNOS gene expression in neonatal PRVs, suggests that the nNOS isoform may be responsible for counteracting angiotensin II increased vascular resistance in immature porcine PRVs.     

Changes in nitric oxide and expression of nitric oxide synthase in spinal cord after acute traumatic injury in rats

The aim of this study was to observe the time course of NO production and NOS expression in the spinal cord following acute traumatic injury. Rat spinal cord was injured by extradural static weight-compression, which resulted in an incomplete transverse spinal cord lesion with paralysis of the lower extremities. Using this model, measurement of NO by microdialysis and Griess reaction and histological and immunohistochemical examinations using polyclonal antibodies to nNOS and iNOS were performed from immediately to 14 days after injury. In injured cord, the amount of NO markedly increased immediately after injury and gradually decreased between 1 and 12 h after injury. A second wave of increase in NO level was observed at 24 h and 3 days after injury. Histologically, hematomas and necrotic changes were observed after injury and demyelination of nerve fibers increased with time in the compressed segment. Immunohistochemically, the number of cells with expression of nNOS was increased immediately to 12 h after injury. Expression of iNOS was observed from 12 h to 3 days after injury. These findings suggested that the initial maximal increase of NO production might be caused mainly by nNOS and that the second wave of increase in NO might be due mainly to iNOS.     

Time course of expression of three nitric oxide synthase isoforms after transient middle cerebral artery occlusion in rats

The involvement of nitric oxide synthase (NOS) in ischemia was evaluated by detecting the expression of neuronal NOS (nNOS), endothelial NOS (eNOS), and inducible NOS (iNOS) by the immunohistochemical method in the rat model of middle cerebral artery (MCA) occlusion. Transient MCA occlusion (2 hours) was induced in 32 male Wistar rats by extracranial insertion of a 3-0 nylon thread through the internal carotid artery into the MCA. Animals were killed at 0, 6, 24, 72, and 168 hours after MCA occlusion (n = 6, 6, 8, 6, and 6, respectively). The brains were fixed with periodate-lysine-paraformaldehyde, frozen, and sectioned. Sections were stained with polyclonal antibody against nNOS, eNOS, and iNOS. Each section was evaluated by microscopic observation (x100). The number of nNOS-positive neurons was 41.6 +/- 5.8 (mean +/- SD) in the control hemisphere. nNOS was upregulated in the ischemic hemisphere (88.3 +/- 18.9), especially in the border zone at 6 hours after MCA occlusion. However, the number decreased to 36.4 +/- 3.6 and 26.3 +/- 7.3 in the ischemic hemisphere after 72 and 168 hours, respectively. eNOS immunoreactivity was present in the endothelium of major vessels at each time point. eNOS was not detected in the microvessels before ischemia, but faint staining was found in the endothelium at 6 hours after MCA occlusion. Immunostaining became more intense thereafter. Faint iNOS immunoreactivity was seen in the microvessels at 6 hours after MCA occlusion. Macrophages in the ischemic core and astrocytes in the border zone showed immunoreactivity to iNOS at 72 and 168 hours after MCA occlusion. Three types of NOS must be related to different stages of ischemic brain damage. nNOS may be neurotoxic in ischemia in the early phase, like iNOS in the late phase. On the other hand, eNOS seemed to be neuroprotective in all stages. These observations suggest the necessity for tailored therapeutic intervention against NOS isoforms at each stage in patients with ischemic stroke.