Technique assessment of demyelination from endoneurial injection

Solutions or sera can be subperineurally injected into rat nerve to test their neuropathologic and, especially, their demyelinating effects. In the present study we assessed the effect of the endoneurial injection technique itself. The rate of axonal degeneration and segmental demyelination increased wth extraneous movement (of the needle or the animal), increasing needle size, rapid injection, and large volumes of injectate. We showed that graded evaluation of the pathologic abnormalities of teased fibers provides a more sensitive measure of demyelination than does evaluation of transverse sections. Transverse sections provide an inadequate approach to assess the rate of axonal degeneration. Using these approaches, no difficulty was encountered in demonstrating the greatly increased demyelinating activity of 5 nmol lysolecithin (lysophosphatidylcholine) compared with lactated Ringer's solution.