Induction of neuronal and inducible nitric oxide synthase in the motoneurons of spinal cord following transient abdominal aorta occlusion in rats.
BACKGROUND
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.


METHODS
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.


RESULTS
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.


CONCLUSIONS
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.
Zhou
Y
Y
Department of Experimental Surgery, Singapore General Hospital, 169608, Singapore. zhouy_twh@yahoo.com
Zhao
Y N
YN
Yang
E B
EB
Ling
E A
EA
Wang
Y
Y
Hassouna
M M
MM
Mack
P
P
D000818:Animals; D001012:Aorta, Abdominal; D001157:Arterial Occlusive Diseases / Q000201:enzymology; D004790:Enzyme Induction; D007150:Immunohistochemistry; D007511:Ischemia / Q000201:enzymology*; D008297:Male; D009046:Motor Neurons / Q000201:enzymology*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009569:Nitric Oxide / Q000502:physiology; D019001:Nitric Oxide Synthase / Q000096:biosynthesis*; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000098:blood supply*
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; D052247:Nitric Oxide Synthase Type II; C496322:Nos1 protein, rat; C496318:Nos2 protein, rat; D009252:NADPH Dehydrogenase