Previous reports documented demonstrated that
melatonin, a
free radical scavenger, is important in protecting against oxidative stress-induced tissue damage after
spinal cord injury (SCI). This study was undertaken to investigate the effects of
pinealectomy (PX) and administration of exogenous
melatonin after SCI in rats. These animals were randomized into six groups, each having 12 rats. Group 1 underwent
laminectomy alone. Group 2 underwent
laminectomy followed by SCI and received no medication. Group 3 underwent
laminectomy followed by SCI and received
melatonin. Group 4 underwent PX and
laminectomy alone. Group 5 underwent PX and
laminectomy followed by SCI and received no medication. Group 6 underwent PX and
laminectomy followed by SCI and received
melatonin.
Melatonin (100 mg/kg) was given intraperitoneally immediately after
trauma to the rats in the groups 3 and 6. PX caused a significant increase in the
malondialdehyde (MDA),
nitrite oxide (NO),
glutathione (GSH),
xanthine oxidase (XO) levels and decrease in GSH levels as compared with the control group.
Trauma to the spinal cord results in significantly higher oxidative stress.
Melatonin administration significantly reduced MDA, XO and NO levels, and increased GSH levels in the spinal cord after
trauma. Exogenous
melatonin treatment after
trauma attenuated tissue lesion area and accelerated motor recovery rate. These findings suggest that reduction in endogenous
melatonin after PX makes the rats more vulnerable to
trauma and exogenous
melatonin administration has an important
neuroprotective effect on the level of the spinal cord.