RESUMO
In this work, we have immunohistochemically analyzed the effects of single injections of apotransferrin (aTf) on the expression of myelin (myelin basic proteins [MBPs]) and axonal (protein gene product 9.5 [PGP 9.5] and beta(III)-tubulin [beta(III)-tub]) proteins in colchicine-injected and crushed sciatic nerves of adult rats. A protein redistribution was seen in the distal stump of injured nerves, with the appearance of MBP- and PGP 9.5-immunoreactive (IR) clusters which occurred earlier in crushed nerves (3 days post-injury [PI]) as compared to colchicine-injected nerves (7 days PI). beta(III)-tub-IR clusters appeared at 1 day PI preceding the PGP 9.5- and MBP-IR clusters in colchicine-injected nerves. With image analysis, the peak of clustering formation was found at 14 days PI for MBP and at 3 days PI for beta(III)-tub in colchicine-injected nerves. At 28 days of survival, the protein distribution patterns were almost normal. The intraneural application of aTf, at different concentrations (0.0005 mg/ml, 0.005 mg/ml, 0.05 mg/ml, 0.5 mg/ml), prevented nerve degeneration produced by colchicine, with the appearance of only a small number of MBP- and beta(III)-tub-IR clusters. However, aTf was not able to prevent clustering formation when the nerve was crushed, a kind of injury that also involves necrosis and blood flow alterations. The results suggest that aTf could prevent the colchicine effects by stabilizing the cytoskeleton proteins of the nerve fibers, avoiding the disruption of the axonal transport and thus the myelin degeneration. Transferrin is proposed as a complementary therapeutic avenue for treatment of cytotoxic nerve injuries.
Assuntos
Apoproteínas/farmacologia , Axônios/efeitos dos fármacos , Proteínas do Tecido Nervoso/efeitos dos fármacos , Neuropatia Ciática/tratamento farmacológico , Transferrina/farmacologia , Degeneração Walleriana/tratamento farmacológico , Degeneração Walleriana/prevenção & controle , Animais , Transporte Axonal/efeitos dos fármacos , Transporte Axonal/fisiologia , Axônios/metabolismo , Colchicina/antagonistas & inibidores , Colchicina/toxicidade , Citoesqueleto/efeitos dos fármacos , Citoesqueleto/metabolismo , Citoesqueleto/patologia , Modelos Animais de Doenças , Relação Dose-Resposta a Droga , Imuno-Histoquímica , Microtúbulos/efeitos dos fármacos , Microtúbulos/metabolismo , Microtúbulos/patologia , Proteína Básica da Mielina/efeitos dos fármacos , Proteína Básica da Mielina/metabolismo , Bainha de Mielina/efeitos dos fármacos , Bainha de Mielina/metabolismo , Bainha de Mielina/patologia , Proteínas do Tecido Nervoso/metabolismo , Fármacos Neuroprotetores/farmacologia , Neurotoxinas/antagonistas & inibidores , Neurotoxinas/toxicidade , Ratos , Ratos Wistar , Neuropatia Ciática/metabolismo , Neuropatia Ciática/fisiopatologia , Resultado do Tratamento , Tubulina (Proteína)/efeitos dos fármacos , Tubulina (Proteína)/metabolismo , Ubiquitina Tiolesterase/efeitos dos fármacos , Ubiquitina Tiolesterase/metabolismo , Degeneração Walleriana/fisiopatologiaRESUMO
In this work we analyzed variations in the expression of MBPs and P0 in ligated sciatic nerves of young and adult rats at 3, 7, and 14 days postligation (PL), by immunohistochemistry and SDS-PAGE of isolated myelin. A protein redistribution was seen in the distal stump of ligated nerves with the appearance of immunoreactive clusters. Using the KS400 image analyzer, immunostained area values were obtained from the different nerves dissected. In adult rats, there was an increase of the immunostained area for MBP from 3 to 7 days PL, coincident with a reorganization of the marker in clusters, followed by a marked decrease at 14 days. P0 immunolabeling gave similar results without, however, a decrease of the immunostained area at the longer survival time tested. Young animals showed an acceleration in the process of protein redistribution and digestion within ligated nerves, which followed a similar pattern as that of adult animals. Analysis by electrophoresis showed a marked decrease in P0 and MBP at 7 days PL in young rats and 14 days PL in adult rats. The functional significance of protein clustering within myelin in injured nerves deserves further analysis.