Zhou Y, Zhao Y N, Yang E B, Ling E A, Wang Y, Hassouna M M, Mack P
Department of Experimental Surgery, Singapore General Hospital, 169608, Singapore.
J Surg Res. 1999 Dec;87(2):185-93. doi: 10.1006/jsre.1999.5754.
Motoneurons in the spinal cord are especially vulnerable to ischemic injury and selectively destroyed after transient ischemia. Nitric oxide (NO) has been implicated in both neurodegneration and neuroprotection to ischemic insult. To evaluate the role of NO in pathophysiology to spinal cord ischemia, the expression of neuronal and inducible nitric oxide synthase (n-NOS and i-NOS) and nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) in the motoneurons of the lumbosacral spinal cord was examined in a rat model with transient abdominal aorta (TAA) occlusion.
Male Sprague-Dawley rats were divided into sham-operated (n = 12) and TAA occlusion (n = 24) groups. TAA occlusion was induced by placement of a microvascular clamp around the abdominal aorta for 20 min. Three sham-operated and six TAA occlusion animals were sacrificed at each time interval at 4, 24, and 48 h and 7 days after operation. Tissue sections obtained from the lumbosacral spinal cord were processed for n-NOS, i-NOS, NADPH-d, and hematoxylin-eosin (HE) staining. Histological changes of motoneurons in ventral horn were assessed by HE staining.
In sham-operated control animals, n-NOS-, i-NOS-, and NADPH-d-positive neurons were barely detectable in the ventral horn of the spinal cord. At 4 h after TTA occlusion, n-NOS and NADPH-d expression became evident in the motoneurons and was markedly enhanced at 24 and 48 h. i-NOS expression was also induced in the ventral horn motoneurons of the lumbosacral spinal cord at the same time points. Enzymatic expression in the motoneurons was diminished 7 days after operation. Hyperchromatic neurons indicative of cell death were observed in HE-stained specimens 7 days following TAA occlusion.
The rapid induction of n-NOS, i-NOS, and NADPH-d in the motoneurons of ventral horn suggests that NO may be involved in the selective and delayed neuronal death in the spinal cord to the ischemic insult.
脊髓运动神经元对缺血性损伤尤为敏感，在短暂缺血后会被选择性破坏。一氧化氮（NO）在神经变性和对缺血性损伤的神经保护中均有涉及。为评估NO在脊髓缺血病理生理学中的作用，在大鼠短暂性腹主动脉（TAA）阻断模型中，检测了腰骶部脊髓运动神经元中神经元型和诱导型一氧化氮合酶（n-NOS和i-NOS）以及烟酰胺腺嘌呤二核苷酸磷酸黄递酶（NADPH-d）的表达。
雄性Sprague-Dawley大鼠分为假手术组（n = 12）和TAA阻断组（n = 24）。通过在腹主动脉周围放置微血管夹20分钟诱导TAA阻断。在术后4、24、48小时和7天的每个时间间隔，处死3只假手术动物和6只TAA阻断动物。从腰骶部脊髓获取的组织切片进行n-NOS、i-NOS、NADPH-d和苏木精-伊红（HE）染色。通过HE染色评估腹侧角运动神经元的组织学变化。
在假手术对照动物中，脊髓腹侧角几乎检测不到n-NOS、i-NOS和NADPH-d阳性神经元。TTA阻断后4小时，n-NOS和NADPH-d在运动神经元中的表达变得明显，并在24和48小时显著增强。在相同时间点，腰骶部脊髓腹侧角运动神经元中也诱导出i-NOS表达。术后7天，运动神经元中的酶表达减少。TAA阻断7天后，在HE染色标本中观察到指示细胞死亡的嗜色神经元。
腹侧角运动神经元中n-NOS、i-NOS和NADPH-d的快速诱导表明，NO可能参与脊髓对缺血性损伤的选择性和延迟性神经元死亡。
