Antisense oligos to neuronal nitric oxide synthase aggravate motoneuron death induced by spinal root avulsion in adult rat.
The present study used nitric oxide synthase (nNOS) antisense oligos (nNOS AS-ODN) to assess the role of nNOS in motoneuron death induced by spinal root avulsion. A right seventh cervical (C7) spinal root avulsion was performed on adult male Sprague-Dawley rats. Two weeks later, FITC-labeled random oligos (FITC-R-ODN), nNOS AS-ODN, R-ODN or TE buffer was applied to the lesioned side of the C7 spinal segment and refreshed every 3 days. FITC-R-ODN was first detected inside the injured motoneurons at 10 h, accumulated to a maximum by 24 h and faded out from 72 h. Following avulsion, nNOS AS-ODN decreased the number of nNOS-positive motoneurons in the lesioned segment compared either with buffer (P < 0.001 at 15 days, 3 and 4 weeks post-injury) or with R-ODN control (P = 0.002 at 15 days, P < 0.001 at 3 and 4 weeks post-injury). Interestingly, nNOS AS-ODN also decreased the number of surviving motoneurons compared either with buffer (P = 0.005 at 15 days, P < 0.001 at 3 or 4 weeks) or with R-ODN control (P < 0.001 at 3 or 4 weeks). Meanwhile, there were no significant differences between R-ODN and buffer control either in the number of nNOS-positive motoneurons (P = 0.245 at 15 days, P = 0.089 at 3 weeks and P = 0.162 at 4 weeks) or in the number of surviving motoneurons (P = 0.426 at 15 days, P = 0.321 at 3 weeks or P = 0.344 at 4 weeks). These findings indicate that nNOS AS-ODN, applied from 2 weeks after avulsion, aggravates the motoneuron death due to root avulsion by specifically down-regulating nNOS gene expression and that the expression of nNOS in adult spinal motoneurons in response to root avulsion may play a beneficial role in the survival of injured neurons.
Zhou
Lihua
L
Department of Anatomy, Faculty of Medicine, The University of Hong Kong, 21 Sassoon Road, Hong Kong, China.
Wu
Wutian
W
D000818:Animals; D002452:Cell Count; D016923:Cell Death / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D016650:Fluorescein-5-isothiocyanate; D005456:Fluorescent Dyes; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D007150:Immunohistochemistry; D007278:Injections, Spinal; D008297:Male; D009046:Motor Neurons / Q000473:pathology*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D052248:Nitric Oxide Synthase Type I / Q000096:biosynthesis / Q000235:genetics*; D016376:Oligonucleotides, Antisense / Q000008:administration & dosage / Q000138:chemical synthesis / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013116:Spinal Cord / Q000473:pathology; D013119:Spinal Cord Injuries / Q000473:pathology*
D005456:Fluorescent Dyes; D016376:Oligonucleotides, Antisense; D052248:Nitric Oxide Synthase Type I; D009252:NADPH Dehydrogenase; D016650:Fluorescein-5-isothiocyanate