The recovery of 5-HT transporter and 5-HT immunoreactivity in injured rat spinal cord.
METHODS
Experimental spinal cord injury.


OBJECTIVE
To determine the role of serotonin (5-HT) and 5-HT transporter in recovery from spinal cord injury.


METHODS
We examined 5-HT and 5-HT transporter of spinal cord immunohistologically and assessed locomotor recovery after extradural compression at the thoracic (T8) spinal cord in 21 rats. Eighteen rats had laminectomy and spinal cord injury, while the remaining three rats received laminectomy only. All rats were evaluated every other day for 4 weeks, using a 0-14 point scale open field test.


RESULTS
Extradural compression markedly reduced mean hindlimbs scores from 14 to 1.5 +/- 2.0 (mean +/- standard error of mean). The rats recovered apparently normal walking by 4 weeks. The animals were perfused with fixative 1-3 days, 1, 2 and 4 weeks (three rats in each) after a spinal cord injury. The 5-HT transporter immunohistological study revealed a marked reduction of 5-HT transporter-containing terminals by 1 day after injury. By 4 weeks after injury, 5-HT transporter immunoreactive terminals returned to the control level. The 5-HT immunohistological study revealed a reduction of 5-HT-containing terminals by 1 week after injury. By 4 weeks after injury, 5-HT immunoreactive fibers and terminals returned to the control level.


CONCLUSIONS
We estimated the recovery of 5-HT transporter and 5-HT neural elements in lumbosacral ventral horn by ranking 5-HT transporter and 5-HT staining intensity and counting 5-HT and 5-HT transporter terminals. The return of 5-HT transporter and 5-HT immunoreactivity of the lumbosacral ventral horn correlated with locomotor recovery, while 5-HT transporter showed closer relationship with locomotor recovery than 5-HT. The presence of 5-HT transporter indicates that the 5-HT fibers certainly function. This study shows that return of the function of 5-HT fibers predict the time course and extent of locomotory recovery after thoracic spinal cord injury.
Saruhashi
Yasuo
Y
Department of Orthopedic Surgery, Shiga University of Medical Science, Setatsukinowacho Otsu, Shiga, 520-2192, Japan. saruhasi@belle.shiga-med.ac.jp
Matsusue
Yoshitaka
Y
Fujimiya
Mineko
M
D000818:Animals; D004195:Disease Models, Animal; D007150:Immunohistochemistry; D008297:Male; D009043:Motor Activity; D051381:Rats; D017208:Rats, Wistar; D020127:Recovery of Function; D012701:Serotonin / Q000032:analysis* / Q000378:metabolism; D050486:Serotonin Plasma Membrane Transport Proteins / Q000032:analysis* / Q000378:metabolism; D013116:Spinal Cord / Q000737:chemistry* / Q000378:metabolism; D013117:Spinal Cord Compression / Q000378:metabolism*; D013904:Thoracic Vertebrae; D016896:Treatment Outcome
D050486:Serotonin Plasma Membrane Transport Proteins; D012701:Serotonin