Modulation of Motoneuron Excitability by Brain-Derived Neurotrophic Factor. Gonzalez, Michael and William F. Collins, III. Department of Neurobiology and Behavior, SUNY at Stony Brook, Stony Brook, New York 11794-5230.
APStracts 3:0218N, 1996.
The influence of neurotrophins on motoneuron survival and development has been well documented in cell cultures and neonates. In the present study, the role of BDNF in the maintenance of motoneuron electrical properties was investigated. In adult male rats, BDNF- or saline-saturated gelfoam was inserted between the medial and lateral heads of the gastrocnemius muscles. After 5 days survival, in vivo intracellular recordings were obtained, and motoneuron biophysical properties were measured. In BDNF-treated rats, significant decreases in mean rheobase and in total cell capacitance of medial gastrocnemius motoneurons were observed. In addition, a concommitant increase in input resistance and decrease in membrane time constant were noted in BDNF treated rats but were not statistically significant. No significant treatment effect was observed in motoneuron conduction velocity, action potential amplitude, equalizing time constant, electrotonic length, after- hyperpolarization amplitude and duration, and membrane potential sag during current injection. The observed changes in motoneuron rheobase and total cell capacitance suggest that application of BDNF produces an increase in motoneuron excitability coincident with a reduction in size. These data are discussed with respect to the possible role of BDNF as a muscle-derived trophic factor for the regulation of motoneuron excitability.

Received 14 June 1996; accepted in final form 18 September 1996.
APS Manuscript Number J475-6.
Article publication pending J. Neurophysiol.
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996