ABSTRACT
PURPOSE: The neurotrophic factor fibroblast growth factor-2 (FGF-2, bFGF) and Ca++ binding protein S100ß are expressed by the Schwann cells of the peripheral nerves and by the satellite cells of the dorsal root ganglia (DRG). Recent studies have pointed out the importance of the molecules in the paracrine mechanisms related to neuronal maintenance and plasticity of lesioned motor and sensory peripheral neurons. Moreover, cultured Schwann cells have been employed experimentally in the treatment of central nervous system lesions, in special the spinal cord injury, a procedure that triggers an enhanced sensorymotor function. Those cells have been proposed to repair long gap nerve injury. METHODS: Here we used double labeling immunohistochemistry and Western blot to better characterize in vitro and in vivo the presence of the proteins in the Schwann cells and in the satellite cells of the DRG as well as their regulation in those cells after a crush of the rat sciatic nerve. RESULTS: FGF-2 and S100ß are present in the Schwann cells of the sciatic nerve and in the satellite cells of the DRG. S100ß positive satellite cells showed increased size of the axotomized DRG and possessed elevated amount of FGF-2 immunoreactivity. Reactive satellite cells with increased FGF-2 labeling formed a ring-like structure surrounding DRG neuronal cell bodies.Reactive S100ß positive Schwann cells of proximal stump of axotomized sciatic nerve also expressed higher amounts of FGF-2. CONCLUSION: Reactive peripheral glial cells synthesizing FGF-2 and S100ß may be important in wound repair and restorative events in the lesioned peripheral nerves.
OBJETIVO: O fator neurotrófico fator de crescimento de fibroblastos-2 (FGF-2, bFGF) e a proteína ligante de Ca++ S100ß são expressos pelas células de Schwann dos nervos e por células satélites do gânglio da raiz dorsal (GRD). Estudos recentes indicam a importância das moléculas nos mecanismos parácrinos relacionados à manutenção neuronal e à plasticidade de neurônios periféricos motores e sensoriais. Além disso, células de Schwann cultivadas têm sido empregadas experimentalmente no tratamento de lesões no sistema nervo central, especialmente na lesão da medula espinal, a qual mostrou uma melhora da função sensoriomotora. Estas células são ainda propostas no reparo do nervo lesado com perda de tecido. MÉTODOS: Usamos a dupla marcação imunohistoquímica e o Western blot para caracterizar melhor in vitro e in vivo a presença das proteínas nas células de Schwann e nas células satélites do GRD assim como sua regulação nessas células após a compressão do nervo ciático de ratos. RESULTADOS: FGF-2 e S100ß estão presentes nas células de Schwann do nervo ciático e nas células satélites do GRD. Células satélites do GRD axotomizado positivas para S100ß possuíam quantidade aumentada de imurreatividade da FGF-2. Células satélites reativas apresentando maior quantidade de FGF-2 formaram um anel ao redor dos corpos neuronais do GRD. Células de Schwann do coto proximal à axotomia do nervo ciático e positivas para S100ß também expressaram quantidades aumentadas de FGF-2. CONCLUSÃO: As células gliais periféricas ao sintetizar FGF-2 e S100ß podem ser importantes no reparo de cicatrização e em eventos restaurativos nas lesões do nervo.
Subject(s)
Animals , Male , Rats , /metabolism , Ganglia, Spinal/metabolism , Nerve Growth Factors/metabolism , Peripheral Nerves/injuries , /metabolism , Schwann Cells/metabolism , Axotomy , Blotting, Western , Cells, Cultured , /analysis , Ganglia, Spinal/chemistry , Ganglia, Spinal/cytology , Immunohistochemistry , Nerve Crush , Nerve Growth Factors/analysis , Paracrine Communication , Peripheral Nerves/physiology , Peripheral Nerves/surgery , Rats, Wistar , /analysis , Satellite Cells, Perineuronal/metabolism , Schwann Cells/cytology , Sciatic Nerve/cytology , Sciatic Nerve/injuries , Sciatic Nerve/metabolismABSTRACT
Objective:To investigate the expression of GDNF mRNA on proximal end of sciatic nerve and T 12 L 1 spinal cord after sciatic nerve was cut in rats. Methods:The sciatic nerve of proximal end and spinal cord paralleling T 12 L 1 nerve root was taken respectively before and after sciatic nerve were severed. The level of GDNF mRNA on proximal end of sciatic nerve and spinal cord was observed and compared before and after sciatic nerve cut. Semi quantitative RT PCR method with ? actin as an inner consult was used to detect the expression of GDNF mRNA. Results:GDNF mRNA expression decreased by 10% 24 h after sciatic nerve was cut, 38% 7 d later, 45% 14 d and 52% 28 d in proximal end, while it decreased by 20%, 68%,80% and 85% on 1, 7, 14 and 28 d respectively in the spinal cord. Conclusion:The reduction of GDNF mRNA level on proximal end and homologous segmental spinal cord may be caused by losing the support of GDNF mRNA from the target tissue after sciatic nerve cut. This study provides a foundation for foreign GDNF to be used in treating SCI.