Investigation of the effects of experimental demyelinization process on peripheral nerve velocity and excitability

Damage to Schwann cells of neurons forming the peripheral nervous system, demyelination; the healing process of this damage is also called remyelination. Remyelination does not occur completely in all cases; therefore, various peripheral nervous system diseases occur. One of the methods used to model these diseases on animals is injecting lysophosphotidylcholine into the nerve sheath by microinjection. In order to detect injuries in nerve cells, the electrical properties of these cells are examined. Threshold tracking method provides data collection on electrical properties of nerve cells such as membrane capacitance and resistance, and ion channel kinetics by applying different pulse patterns to nerves. Different pulse patterns are expressed by different protocols. Protocols named stimulus-response relationship, strength-duration time constant, recovery cycle, threshold electrotonus and current-threshold reduction address different electrical properties of nerve cells. In this study, in order to monitor the demyelination and remyelination processes, to capture their onset and to examine how the channel kinetics in the nerve fiber change during these processes, excitability measurements were made 3 days, 7 days, 10 days and 20 days after the injection of lysophosphotidylcholine from different animals and compared with the control group. When the findings obtained as a result of this study are examined, the course of group averages in many parameters gives results that are generally compatible with the literature. Although there is no significant difference in maximum compound action potential (CAP) amplitude, it is roughly seen that demyelination and remyelination occur and the LPC microinjection model is successfully applied when considered together with the stimulus strength required for 50% of the maximum response. When the rheobase and SDTC values are examined, it is seen that demyelination with LPC is achieved in an average of 3 days and then remyelination occurs. Stimulus charge-width values also support the result in the previous sentence. These data show that the ion channel distribution changes with demyelination and returns to its previous state, albeit partially, with remyelination.