Neuroprotective Effects of Hypothermia After Spinal Cord Injury in Rats Comparative Study Between Epidural Hypothermia and Systemic Hypothermia

Study Design. An experimental comparative study on moderate epidural hypothermia (MEH) versus moderate systemic hypothermia (MSH) after spinal cord injury (SCI). Objective. To compare neuroprotective effects of hypothermia between MEH and MSH after SCI in rats. Summary of Background Data. Experimental MEH or MSH has been attempted for neuroprotection after ischemic or traumatic SCI. However, there is no comparative study on neuroprotective effect of MEH and MSH after SCI. If hypothermia is to be considered as 1 modality for treating SCI, further studies on the advantages and disadvantages of hypothermia will be mandatory. Methods. A spinal cord contusion was produced in all 32 rats, and these rats were randomly divided into 4 groups-8 rats in each group: (1) the control group (spinal cord contusion only), (2) the methylprednisolone group, (3) the MEH group (28 degrees C for 48 hr), and (4) the MSH group (32 degrees C for 48 hr). The functional recovery was assessed using Basso, Beattie, Bresnahan scale and antiapoptotic and anti-inflammatory effects were assessed. Results. The Basso, Beattie, Bresnahan scale scores in both the hypothermia groups were significantly higher than that in the control group at 6 weeks. The numbers of terminal deoxynucleotidyl transferase dUTP nick end labeling-positive cells and OX-42 positive cells were significantly lower in both the MEH and MSH groups than that in the control group. The p38 mitogen-activated protein kinases expression of the treated groups was significantly lower than that of the control group. The expression of caspase-8 and caspase-9 significantly decreased in the treated groups compared with that of the control group. However, in terms of caspase-3, only the MSH group has shown to be significantly lower than that of the control group. Conclusion. This study presented that both systemic and epidural hypothermia demonstrated neuroprotective effects after SCI. Systemic hypothermia showed more neuroprotective effect by antiapoptotic and anti-inflammatory effects.