[Apoptosis and caspase-12 expression in progressive compressive spinal cord injury: experiment with rats].

Objective: To investigate the apoptosis and caspase-12 expression in progressive compression of spinal cord (PCSC).
Methods: 120 adult Wistar rats were randomly divided into 2 equal groups, experimental group, undergoing operation so as to establish PCSC models, and control group, undergoing sham operation. 1, 3, 7, 14, 21, and 28 days after the operation, 5 rats from each group were anesthetized with their spinal cords taken out. TUNNEL method was used to observe the apoptosis of the neurons in the compressed segments. Another 5 rats from each group at different time points were anesthetized with their spinal cords as well. Immunohistochemistry was used to detect the mRNA expression of caspase-12 in the compressed segments. Western blotting was used to detect the protein expression of caspase-12.
Results: The apoptotic rates of neurons and gliocytes 1, 3, 7, 14, 21, and 28 days after were 12.5% +/- 2.3%, 13.0% +/- 3.6%, 17.2% +/- 4.3%, 29.4% +/- 4.4%, 36.1% +/- 6.5%, and 2.3% +/- 7.9% respectively, with significant differences among the values 14, 21, and 28 days and those at other time points after the operation (all P < 0.05). Immunohistochemistry showed that the number of caspase-12 positive neurons increased since 1 day after, and became remarkably high 14, 21, and 28 days after with significant differences among different time points (all P < 0.05). Western blotting showed that the protein expression of caspase-12 was low 1, 3, and 7 days after, and peaked 14 days after, and then gradually decreased, however, the expression levels 21 and 28 days after were still significantly higher then those 1, 3, and 7 days after (all P < 0.05).
Conclusion: Caspase-12 is involved in the apoptosis of neurons in PCSC.