Ss. Haghighi et al., Effects of methylprednisolone and MK-801 on functional recovery after experimental chronic spinal cord injury, SPINAL CORD, 38(12), 2000, pp. 733-740
Study design: An experimental study was conducted to evaluate the effects o
f methylprednisolone and MK-801 after the compressive injury of spinal cord
in rats.
Objectives: To investigate the effect of methylprednisolone and non-competi
tive NMDA antagonist MK-801 in long-term functional outcome after spinal co
rd injury (SCI).
Methods: A randomized group A of Sprague-Dawley rats were treated with MK-8
01 (1.0 mg/kg, n=10; Group A) after a compression injury. A group of methyl
prednisolone (MP)-treated (30 mg/kg, n=10; Group B) and non-treated animals
(n=9; Group C) were included for comparison. The functional motor outcome
such as inclined plane (IP), toe spreading reflex (TSR), and modified Tarlo
v scale (TS) were measured in each animal at regular time points up to 8 we
eks post-treatment. Histologically the injury site was scored in four group
s and immunohistochemically Wallerian Degeneration (WD), astrocytosis and e
xpression of beta -amyloid protein was identified.
Results: In examining the IP data, no significant difference was recognized
between the group means (P-value > 0.5). For the TSR, there were no differ
ences in the group responses. For the TS, the differences were not statisti
cally significant. Only group B showed significance in cavitation scores co
mpared to group A (P > 0.0094), WD was significantly different than group C
(P > 0.03), astrocytosis was significantly higher than group A (P > 0.001)
and modest presence of beta -amyloid protein.
Conclusion: Our data indicate that one time bolus administration of MK-801
lacks any significant effect on axonal function in chronically injured rats
. Daily bolus administration of MP at 30 mg/kg also did not ensure a better
functional outcome. Immunohistochemically we have been able to show signif
icant differences in WD, astrocytosis and small insignificant changes in be
ta -amyloid protein.