| The ion channels, voltage-gated sodium channel (VGSC) and delayed-rectifier potassium channel (DRPC), which are responsible for the saltatory conduction of nerve impulses in peripheral myelinated nerve, are paid less attention in the demyelinated neuropathy. The ion channels in lymphocytes, voltage-gated potassium channel (Kvl.3) and intermediate-conductance calcium-activated potassium channel (IKCal), which are thought to be the potential targets of immunosuppression, are essential to the initiation and developing of immune response in vitro. But their functions in vivo are not clarified to this day. Tripterygium polyglucoside (TP) is an immunosuppressive agent from traditional Chinese herb medicine and is regarded as a potential medicine to Guillain-Barre syndrome (GBS). In this study, we induced experimental allergic neuritis in Lewis rats and investigate the effects of VGSC/DRPC on nerve conduction in peripheral nerve and the relationship between Kvl.S/IKCal and immunologic reaction in lymphocytes from EAN rats. In addition, we observe the therapeutical effect of TP on EAN. Methods and Results:1. Part I The relationship between ion channels and nerve conduction in peripheral nerve form EAN rats.EAN is induced in male Lewis rats by inoculation with bovine peripheral myelin (BPM) and the clinical signs are evaluated. On day 9, 16, 23, 30, 44, 85 post-immunization (p.i.), we observed the histopathology of sciatic nerve and the immunohistochemistry of VGSC, DRPC, myelin associated glycoprotein (MAG) and galactocerebroside (GaiC) in single nerve fibers. We also measured the latency, amplitude and duration of distal compound muscle action potential (CMAP) and calculated motor conduction velocity of sciatic nerve. For investigation of relationship between ion channels and nerve conduction, we calculated the correlation coefficients among the parameters. Results: (1) The clinical signs of EAN onset on about day 9 p.i., reached the maximum on day 16 and disappeared on day 44. (2) The conductionvelocity of sciatic nerve decreased from day 9 p.i., the amplitude and duration of distal CMAPs decreased from day 16, the latency extended from day 23. The changes of all the parameters reached the peak on day 44, and then began to improve slowly. (3) Few inflammatory cells and demyelinated fibers could be found in sciatic nerves of BAN rats on day 16 p.i.. But on day 23, most parts of the nerves were infiltrated by inflammatory cells and large number of the fibers lost. The immunohistochemisrry of myelin basic protein (MBP) and neurofilament (NF) showed that both myelin and axon were damaged. The inflammatory reaction disappeared on day 44 and the nerves had a normal appearance on day 85. (4) Immunohistochemistry of single fibers showed VGSC, DRPC, and MAG decreased significantly on day 9 p.i.. On day 16, the Schwann cell membrane stained by GalC had a vague outline and there were several ripple-like myelin sheaths detached from fibers. On day 23, most parts of the fibers demyelinated and had a foamy appearance, the stain of VGSC, DRPC, and MAG nearly disappeared. On day 30, there were segmental demyelination and ripple-like myelin sheaths, few ion channels and MAG could be found. On day 44, myelin sheath seemed intact and most parts of the fibers had ion channels and MAG stained, although the channel stains looked much weak and less than the normal ones. On day 85, the ion channel clusters still seemed different from the normal ones. (5) According to the correlation coefficients, the ion channels have a high correlation with MAG (about 0.96) and amplitude of distal CMAP (about 0.82), but low correlation with NF and clinical signs (about 0.6).2. Part II The relationship between ion channels and cellular/humoral immunity in lymphocytes from EAN rats.On day 9, 16, 23, 30 p.i., we isolated mononuclear cells from inguinal lymph nodes and spleens in EAN rats and assessed their mRNA expressions of Kvl.3 and IKCal by semi-quantification RT-PCR. After stained with CFSE, the isolated cells were cultured with control pro...
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