X-Ray Exposure Induces Apoptosis of Some Proliferative Epidermal Cells Following Traumatic Spinal Cord Injury in Adult Rats

Abstract

We investigated whether X-ray radiation induced apoptosis of the proliferative ependymal cells (ECs) in adult rats with spinal cord injury (SCI) and the effect of X-ray radiation on the proliferative activities of ECs. A rat model with SCI was developed and used to determine the proliferation and apoptosis of ECs in the spinal cords after X-ray exposure. TUNEL assay and BrdU incorporation were used to detect apoptosis and proliferation respectively. We found that there were few TUNEL-positive cells in proliferative ependymal zone (EZ) after SCI except at the epicenter, and approximately half of the irradiated ECs became TUNEL-positive. However, these radiated ECs did not lose their proliferative activity until 1 week later and started to decrease rapidly after 1 week. The observation suggested that only part of ECs were sensitive to radiation and the nonsensitive cells continued their mitosis process. These findings indicated that X-ray exposure of the rats with SCI in early stage induced apoptosis of the proliferative ECs and partially inhibited their proliferative activities.

Keywords:

• apoptosis
• ependymal cells
• proliferation
• spinal cord injury

Abbreviations:
SCI	=	spinal cord injury
NSCs/NPCs	=	neural stem/precursor cells
ECs	=	ependymal cells
TUNEL	=	terminal deoxynucleotidy transferase-mediated dUTP nick end labeling
FITC	=	fluorescein isothiocyanate
TRITC	=	tetraethyl rhodamine isothiocyanate
EZ	=	ependymal zone
PBS	=	phosphate buffered saline
PB	=	phosphate buffer

Abbreviations:
SCI	=	spinal cord injury
NSCs/NPCs	=	neural stem/precursor cells
ECs	=	ependymal cells
TUNEL	=	terminal deoxynucleotidy transferase-mediated dUTP nick end labeling
FITC	=	fluorescein isothiocyanate
TRITC	=	tetraethyl rhodamine isothiocyanate
EZ	=	ependymal zone
PBS	=	phosphate buffered saline
PB	=	phosphate buffer