The effect of injections of lysophosphatidyl choline into white matter of the adult mouse spinal cord

ABSTRACT The action of lysophosphatidyl choline, LPC, on myelinated fibres in the dorsal white matter of the spinal cord of the adult mouse has been studied electron microscopically, and compared with the recently described activity of LPC in the peripheral nerve fibre. Control injections of sterile isotonic saline and injections of LPC both produced oedematous zones in the white matter; within these zones, many fibres exhibited the characteristic changes of Wallerian degeneration. After injection of LPC, however, an area of demyelination was observed, extending within and beyond the Wallerian degeneration. Ultrastructurally, demyelination involved progressive disruption of the previously-compact sheath, observed initially as a splitting of the intraperiod line within 30 min. Subsequent breakdown was-indicated by the appearance of strands of 4-6 nm repeat lamellar material, itself further degraded through quintuple- and triple-layered lamellar units to disorganized membranous networks around undamaged axons. The significance of the demyelinating activity of LPC is discussed in terms of its known action in in vitro systems of isolated central nervous tissue, and its action in vivo in the peripheral nervous system.