Abnormal nerve conduction studies in mice expressing a mutant form of the POU transcription factor SCIP

• Published in: Journal of neuroscience research Vol. 50; no. 5; pp. 821 - 828
• Main Authors: Bieri, Phyllis L., Arezzo, Joseph C., Weinstein, David E.
• Format: Journal Article
• Language: English
• Published: New York John Wiley & Sons, Inc 01.12.1997
• Subjects: Animals; axon; Evoked Potentials; Mice; Mice, Transgenic; myelin; nerve conduction velocity; Nerve Fibers - physiology; Nerve Fibers - ultrastructure; Nerve Fibers, Myelinated - physiology; Nerve Fibers, Myelinated - ultrastructure; Nerve Tissue Proteins - biosynthesis; Neural Conduction - genetics; Octamer Transcription Factor-6; Peripheral Nerves - abnormalities; Peripheral Nerves - physiology; Peripheral Nerves - ultrastructure; SCIP; Sural Nerve - physiology; Tail - innervation; Tibial Nerve - physiology; Transcription Factors - biosynthesis; Transcription Factors - genetics; transgenic mouse
• ISSN: 0360-4012; 1097-4547
• DOI: 10.1002/(SICI)1097-4547(19971201)50:5<821::AID-JNR18>3.0.CO;2-3

We have previously described transgenic mice that harbor a dominant‐negative antagonist of the POU protein SCIP (termed ΔSCIP). Native SCIP is expressed in promyelinating Schwann cells, where it represses expression of the myelin structural genes. The ΔSCIP mice display morphologic and behavioral abnormalities, including decreased axonal diameter, increased myelin thickness, developmentally early myelination, and clinical features of neuropathy. To assess the neurophysiologic correlates of these abnormalities, a series of electrophysiologic tests was performed. Despite having smaller diameter axons, mice expressing the ΔSCIP transgene had similar maximum conduction velocities in caudal, sural, and tibial nerves compared to wild‐type controls. Therefore, conduction in ΔSCIP animals was faster than predicted by axon diameter alone. Compound amplitude responses were 38% higher in the ΔSCIP caudal nerve. ΔSCIP tibial F‐wave responses showed less difference between minimum and maximum latencies than controls, suggesting less variance between fastest and slowest conducting fibers. These data further characterize the functional components of the ΔSCIP phenotype. In addition, these studies address the physiologic sequelae of altering the g‐ratio in the absence of demyelination or axonal degeneration. J. Neurosci. Res. 50:821–828, 1997. © 1997 Wiley‐Liss, Inc.