Induction of Phosphorylated BAD in Motor Neurons After Transient Spinal Cord Ischemia in Rabbits

Abstract

The mechanism of spinal cord injury has been thought to be related to the vulnerability of spinal motor neuron cells against ischemia. We previously reported that spinal motor neurons might be lost by programmed cell death, and investigated a possible mechanism of neuronal death by immunohistochemical analysis for Phosphorylated Bad (P-Bad) and Bad. We employed rabbit spinal cord ischemia model with an use of balloon catheter. The spinal cord was removed at 8 hours, 1, 2, or 7 days after 15 min of transient ischemia, and western blot analysis for P-Bad and Bad and double-label fluorescence immunocytochemical studies were performed. Western blot analysis revealed no immunoreactivity for P-Bad and Bad in the sham-operated spinal cords. However, they became apparent at 8 hours after transient ischemia, which returned to the baseline level at 1 day. Double-label fluorescence immunocytochemical study revealed that both P-Bad and Bad were positive at 8 hours of reperfusion in the same motor neurons which eventually die. These results suggest that transient spinal cord ischemia activates both cell death and survival pathways after ischemia. The induction of P-Bad protein at the early stage of reperfusion may be one of the factor responsible for the delay in neuronal death after spinal cord ischemia.