Biological differences and molecular mechanism of different peripheral nerves after injury.

OBJECTIVE: The aim of the study was to analyze the apoptosis of neurons and the differences in expression of Bcl-2 and Bax protein in the neurons in the corresponding spinal cord segment after the repair of the tibial nerve (TN) and common peroneal nerve (CPN) in rats.

MATERIALS AND METHODS: 126 healthy male Sprague-Dawley (SD) rats aged 7-8 weeks were randomly divided into group A (control group), group B (TN was cut and sutured), and group C (CPN was cut and sutured), with 42 rats in each group. The spinal cord tissues of rats in different groups were stained with hematoxylin-eosin (HE) on the 1st, 3rd, 7th, 14th, 21st, and 28th day after surgery; the number of neurons in anterior horn of spinal cord, axon density (AD), axon passage rate (APR), and recovery rate (RR) of muscle cell cross-sectional area (MCCA) were calculated; and differences in the expression of Bcl-2 and Bax proteins in the three groups of rats were analyzed by immunohistochemistry.

RESULTS: The results showed that there was no statistically significant difference in the muscle wet weight (MWW) RR of the three groups of rats on the 14th day after the surgery (p>0.05), and the MWW RRs of rats in groups B and C were higher at the 28th day after surgery in contrast to group A (p<0.05). The number of motor neurons in the anterior horn of spinal cord in group B was higher than that in group C at the 3rd, 7th, 14th, and 21st day after surgery (p<0.05); the MWW RR, MCCA, and CSARR of rats in group B were lower than those in group C (p<0.05); the proximal AD, distal AD, and APR in group B were higher than those of group C on the 14th and 28th day after the surgery (p<0.05); and there were no positive staining results in the spinal cord tissue of rats in group A after staining. The expressions of Bcl-2 and Bax in group B were higher observably than the expressions in group C (p<0.05), which indicated that the recovery ability of TN was stronger than that of the CPN; the expression of Bcl-2 and Bax in TN was notably higher than that of the CPN.

CONCLUSIONS: The expression of Bcl-2 and Bax was related to cell apoptosis and nerve regeneration after nerve injury. It provided a reference basis for clinical diagnosis and treatment of peripheral nerves.