Functional protection of pentoxifylline against spinal cord ischemia/reperfusion injury in rabbits: necrosis and apoptosis effects.
BACKGROUND
Little is known about neuronal death mechanisms following spinal cord ischemia. The present study aimed to investigate the protective effect of pentoxifylline (PTX) against spinal cord ischemia/reperfusion (I/R) injury.


METHODS
Rabbits sustained spinal cord ischemia following 45 minutes cross-clamping of the infrarenal aorta. Experimental groups were as follows: the first group of animals (sham, n = 8) underwent laparotomy alone and served as the sham group; the second group (I/R, n = 20) received carrier (3 ml saline solution) and served as the control group; the third group (PTX-A, n = 20) received PTX intravenously 10 minutes prior to ischemia; and the fourth group (PTX-B, n = 20) received PTX intravenously at the onset of reperfusion. Rabbits were evaluated for hind-limb motor function with the Tarlov scoring system at 48 hours. Serum was assayed with enzyme-linked immunosorbent assay for tumor necrosis factor alpha (TNF-alpha) and spinal cords were harvested for myeloperoxidase (MPO) activity, histopathological analysis, terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling staining, platelet/endothelial cell adhesion molecule-1 (PECAM-1) and caspase-3 immunohistochemistry, and the number of necrotic and apoptotic neuron were counted and data analyzed at 12, 24, 48 and 72 hours of reperfusion. Spinal cords were studied by electron microscopy.


RESULTS
Improved Tarlov scores were seen in PTX-treated rabbits as compared with ischemic control rabbits at 48 hours. A significant reduction was found in TNF-alpha in serum, activity of MPO and immunoreactivity of the PECAM-1 and caspase-3 in PTX-treated rabbits. There were fewer apoptotic neurons than necrotic neurons (P < 0.05). A significant decrease in both necrotic and apoptotic neurons was observed in the PTX-treated groups (PTX-A and PTX-B) compared with the I/R group (P < 0.05). Both necrotic and apoptotic neurons were found with the electron microscope.


CONCLUSIONS
PTX may induce protection against ischemia injury in the spinal cord, thereby preventing both necrosis and apoptosis. A major mode of cell death in spinal cord ischemia/reperfusion injury is necrosis while apoptosis is not dominant.
Zhu
Dan-jie
DJ
Department of Orthopedics, Zhejiang Provincial People's Hospital, Hangzhou, Zhejiang 310014, China. zhudj@126.com
Xia
Bing
B
Bi
Qing
Q
Zhang
Shui-jun
SJ
Qiu
Bin-song
BS
Zhao
Chen
C
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3 / Q000378:metabolism; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D046529:Microscopy, Electron, Transmission; D009336:Necrosis; D010431:Pentoxifylline / Q000494:pharmacology* / Q000627:therapeutic use; D011817:Rabbits; D015427:Reperfusion Injury / Q000517:prevention & control*; D013116:Spinal Cord / Q000098:blood supply / Q000473:pathology / Q000648:ultrastructure; D020760:Spinal Cord Ischemia / Q000517:prevention & control*; D014665:Vasodilator Agents / Q000494:pharmacology / Q000627:therapeutic use
D014665:Vasodilator Agents; D053148:Caspase 3; D010431:Pentoxifylline