Journal of Neuroscience, Vol 15, 6926-6938, Copyright © 1995 by Society for Neuroscience
Recovery of tail-elicited siphon-withdrawal reflex following unilateral axonal injury is associated with ipsi- and contralateral changes in gene expression in Aplysia californica
F Noel, WN Frost, LM Tian, MA Colicos and PK Dash
Department of Neurobiology and Anatomy, University of Texas-Houston Health Science Center 77225, USA.
Behavioral, cellular and molecular changes were examined following axonal
injury in the marine mollusc Aplysia californica. Unilateral nerve injury
was performed by crushing the pleural-pedal connective and the peripheral
pedal nerves innervating one side of the posterior body wall and the tail.
The injury procedure severs the axons of the pleural sensory neurons
resulting in the blockade of the tail-elicited siphon- withdrawal reflex.
Partial reflex recovery is observed within 3 d and reaches 50% of the
pretest value by six weeks postinjury. Retrograde staining of injured
nerves combined with electrophysiological recordings from siphon motor
neurons show that axons can regenerate through the crushed site and
reconnect with the tail by three weeks postinjury. Moreover, the behavioral
and electrophysiological measurements suggest that the contralateral
sensory neurons may contribute to the early recovery of the
siphon-withdrawal reflex. The levels of mRNAs coding for actin and
calreticulin are elevated while the mRNAs coding for intermediate filament
protein, sensorin A, FMRFamide are reduced in the ipsilateral pleural
ganglia as detected by Northern blots. In the contralateral pleural
ganglia, the levels of mRNAs coding for actin, sensorin A and FMRFamide are
elevated. These molecular changes in both the ipsi- and contralateral sides
are consistent with the hypothesis that both sides are participating in the
behavioral recovery following unilateral axonal injury.
Previous Article | Next Article
