Expression Of Platelet Derived Growth Factor-B After Acute Spinal Cord Injury In Rats

Background and objective: Neuronal regeneration has been the front edgetopic of the field of neuroseienee after spinal cord injury. There are various neurotrophie factorsparticipating in the pathologic process of spinal cord injury. Platelet-derived growth factor(PDGF) is combined and secreted by many cells, when it combines the specific receptors onnerve cells, they can promote nerve cell proliferation, differentiation and prevent programmedcell death. PDGF, especially PDGF-B and its receptor are wildly expressed in the nervous system,which are closely related to brain tumors, eerebrovaseular disease and other diseases of thenervous system demyelinating disease. To further comprehend the role of PDGF in the centralnervous system after injury to nerve repair, we used a spinal cord injury model in adultSprague-Dawley rats by the New York University(NYU) restructuredâ…¡device, then we usedimmunohistochemistry method to detect the expression of platelet derived growthfactor-B(PDGF-B) protein; and used RT-PCR to monitor the changes of PDGF-B mRNAMaterials and Methods: Forty-eight health SD female rats weighing 160-200gwere randomly divided into mormal group with 8 rats (as control) and SCI group with 40. Ratswere anesthetized with sodium pentobarbital (30mg/kg, i.p.). New York University (NYU)restructuredâ…¡device was used to impact T₁₀ of exposed spinal cord. Then we observed thechanges of behavior after operation, evaluated motor function of lower limbs by BBB scoring. Atseveral time points (1, 3, 7, 14, 28 d) following the SCI, groups of rats (n=8 each group) wereremoved with the thoracic 9～11 of spinal cord. The segments were sectioned continuously into5μm paraffin slices (n=5 each time) for hematoxylin-eosin (HE) staining andimmunohistochemistry staining with antibody to PDGF-B. Total RNA were extracted, theexpression of PDGF-B mRNA was examined by RT-PCR(n=3).Results: After SCI, the expression of PDGF-B was different from that of control group. 1d later, the number of PDGF-B positive cell showed increased tendency, then the expression ofPDGF-B in neurons becomes high, and maintained at a certain level at 7 d. Until 28 d, thenumber of PDGF-B positive cell reached the peak. Expression of PDGF-B mRNA: 1 d after SCI,expression of PDGF-B mRNA was low, then increased gradually, until to the point of 3 d, the level of PDGF-B mRNA approached the normal level. Then the level of PDGF-B mRNAdescended a little. At 14 d, it began to increase, and to 28 d, the level of PDGF-B mRNA retrivedto the normal level.Conclusion: After SCI, PDGF-B participates in the stress response after nerve injury,and protects endangered neurons. Following by stimulating the role of glial cell proliferation anddifferentiation, it involves in the glial cell activation, proliferation of pathological changes. Onthe other side, PDGF-B can combine with PDGF-B receptor of endangered neurons to genetateneuroprotective effect, it is noted that PDGF-B can support and give nutrition to nerve cells. So,after spinal cord injury, PDGF-B plays an important role in spinal cord functional recovery.