Changes of endogenous Spastin expression after sciatic nerve injury in rats

Abstract

To investigate the expression change of endogenous Spastin after sciatic nerve injury in rats, and to discuss the role and significance in the peripheral nerve regeneration. Thirty-six adult male Sprague Dawley rats weighing 180-220 g were randomly divided into the experimental group ( n=30) and the control group ( n=6). Sciatic nerve compression damage model was established in the experimental group, and the sciatic nerve was only exposed in the control group. The L 4-6 spinal cord tissue was obtained to detect Spastin mRNA and protein levels by real-time fluorescence quantitative PCR and Western blot at 1, 3, 7, 14, and 28 days after operation in the experimental group ( n=6) and at 7 days in the control group. Meanwhile, the sciatic nerve at 5 mm distal to the injured site was obtained to observe the ultrastructure of the distal axon by transmission electron microscope (TEM). The expression trends of Spastin gene and Spastin protein in L 4-6 spinal cord tissue of 2 groups were basically identical. In the experimental group, the expressions of Spastin gene and protein decreased at the beginning, and then increased; the expressions reduced to the minimum at 7 days after operation, and came back to the initial level at 28 days. The expression levels of Spastin mRNA and protein at 3, 7, and 14 days were significantly lower in the experimental group than the control group ( P<0.05), but no significant difference was noted between 2 groups at 1 and 28 days ( P>0.05). The expression levels of Spastin mRNA and protein at 3, 7, and 14 days were significantly lower than those at 1 and 28 days in the experimental group ( P<0.05), but no significant difference was noted between at 1 day and 28 days ( P>0.05). At 1, 3, and 7 days after operation, the myelin damage was observed by TEM; at 14 days, there were regenerating Schwann cells; at 28 days, a large number of myelinated nerve fibers were seen, which were closed to normal form. In the process of sciatic nerve regeneration after injury, a complex succession of changes take place in the expression of endogenous Spastin protein in rats, indicating that Spastin protein plays an important role in the process.