| Successful regeneration of peripheral nerve involves protecting neuronal cell bodies, regeneration of axon, and formation of functional synapses. At the present, there are three main approaches used to improve the regeneration and functional rehabilitation of peripheral nerves, namely mechanical rehabilitation (microsurgical operation), implantation of Schwann cells(SCs), electrical stimulation and the application of neurotrophic factors. Neurotrophic factors play an important role in the rescue of damaged neuron, the preventing degeneration and necrosis of neurons, and the increasing axonal regeneration rate. And thus it provided a beneficial microenvironment for the regeneration of nerves and functional recovery in a regeneration nerve. Ciliary neurotrophic factor (CNTF) has many biological activities, such as protective effect on the neuron post-injury, especially for motor neuron. CNTF is widely expressed in peripheral nerves as well as in the central nervous system. Its receptors are composed of CNTFRa, LIFR- and gp130. CNTFR, confers specificity for CNTF on the tripartite CNTF receptors. CNTF and its receptors have specific change style after peripheral nerve injury. They play important roles in the nerve regeneration.Neuronal physiological functions are closely relative to neurotrophic factors. The differences in neuronal survival, regeneration of axon, and formation of functional synapses may be due to the expressions of CNTF and its receptors in rats of different ages after nerve injury.Juvenile, adult and senile rats were used in this study .Their sciatic nerves were transected and connected the two ends with silica gel tubules .This study was divided into two parts:(l)The changes and its expressions of CNTF and CNTFRaat mRNA level and protein level in the spinal cord and the sciatic nerve tissues. They were detected by reverse transcriptase PCR (RT-PCR), in situ hybridization(ISH), immunohistochemistry(IHC), and Western blotting.(2) The neuronal damage was detected by Nissl's staining, hematoxylin and eosin (HE) staining and acetylcholinesterase (ACHE) staining. The apoptotic cells in spinal cord were detected by terminal deoxynucleotidy transferease-mediated biotinylated deoxyuridine triphosphate nick end labelling(TUNEL), flow cytometry( Annexin V /PI), and electron microscopy. The expressions of caspaseS and Bcl-xl in spinal cord were detected by IHC and Western blotting. CaspaseS activity was detected by Caspase3 activity assay. The regeneration of nerve was detected by electron microscopy and horseradish peroxidase(HRP) tracing. The ACHE activity of motor endplate was detected by histochemical staining. The functional recovery of nerve was detected by passive movement and nerve conduction velocity (NCV). The main results are as follows:1. The expressions and distribution of CNTF and CNTFR0 in the spinal cord and sciatic nerve in rats of different ages.The positive immunoreactive substances of CNTF and CNTFRa stained by IHC method were brownish yellow. While the positive reactive substances of CNTF and CNTFRa labeled by BCIP/NBT ISH were blue purple. They were all located and detected in the cytoplasm.The results of RT-PCR and Western blotting are as follows:(1) The expression of CNTF and CNTFR. mRNA and protein were detected in sciatic nerve and spinal cord in normal rats of different ages. The expressions of CNTF and CNTFRamRNA and protein in rats of the normal juvenile group were remarkable than those of the normal adult group and thenormal senile group(P<0.05).No differences were found between rats of the normal adult group and the normal senile group(P>0.05).The results may be correlated with the different requirement of CNTF in normal rats of different ages.(2) The expressions of CNTF and CNTFR . mRNA and protein were weakened at Id, 3d, Iw post-injury in the injured sciatic nerve, increased at Id post-injury in the injured side of spinal cord(P<0.05). The expressions of CNTF and CNTFRamRNA and protein increased at 2w, 4w, and decreased at 8w, 12w...
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