Transferrin effects on the expression of myelin basic protein (MBP) after colchicine injection

J. B. AQUINO; M.F. CORONEL; J.M. PASQUINI; E.F. SOTO; C.P. SETTON-AVRUJ; M.J. VILLAR

Orlando, USA

Congreso; Society for Neurosience; 2002

Society for Neuroscience

Myelin basic proteins (MBPs), are major proteins which account for about 30% of total myelin protein content in peripheral nervous system. MBP redistribution was seen in the distal stump of ligated sciatic nerves with the appearance of immunoreactive clusters (Setton-Avruj et al. SFN 1999). Similar effect is produced by colchicine injection into the nerve (Aquino et al. SFN 2001). The peak of appearance of protein clusters is observed at 7 days post-injury. In this work we have analyzed variations in the expression of MBPs in the sciatic nerve after colchicine and apotransferrin (Tf) injection into the sciatic nerve toward the ganglia. Animals were anaesthetized and their right sciatic nerves exposed at the level of the thigh and injected with 1 m l of 10 mM colchicine (in saline) and 1m l of Tf at different dilutions, together. To identify the site of injection a suture was made in the muscle. Animals were allowed to survive for 6 days. Sham animals with saline and colchicine injections were also prepared. The animals were perfused and the ipsilateral and contralateral sciatic nerves were processed with antibodies against MBPs. The results showed a normal pattern of MBPs-like immunoreactivity (LI) in contralateral sciatic nerves. In sham operated animals occasional and localized clusters of MBPs-LI were detected distally to the injection site and seem to be artifacts of the technique. These clusters were observed on the whole distal part of colchicine-injected nerves. Interestingly, with Tf injection a significantly lower appearance of clusters with MBP-LI was observed in the distal region of the nerve. The functional significance of the clusters displaying MBPs-LI has been interpreted as a sign of degradation of the myelin into the injured sciatic nerve. Whether or not the lower numbers of these clusters in Tf injected animals is a sign of protection of the injured nerve by blockage of normal degradative mechanisms after lesion is currently under study.