Jf. Hamilton et Sm. Fredman, CHARACTERIZATION OF NEURONAL REGENERATION IN THE ABDOMINAL-GANGLION OF APLYSIA-CALIFORNICA, Journal of neurobiology, 35(2), 1998, pp. 160-172
The ability of neurons in the abdominal ganglion of Aplysia to regener
ate their axons following brachial nerve crush was studied using retro
grade straining and intracellular dye injection, The duration of the g
ill withdrawal reflex (GWR) was measured prior to and following nerve
crush. Three days after crushing the nerve, the duration of the gill w
ithdrawal reflex was reduced to 20% of control levels. There was rapid
recovery 19 days after crushing the branchial nerve. The GWR duration
returned to control levels by postlesion days 25-27. Same of the beha
vioral recovery can be attributed to axonal regeneration. Regeneration
, as evidenced by retrograde staining, was first observed by postlesio
n day 15. The number of stained neurons in ganglia with crushes increa
sed until postlesion day 33. The number of stained neurons in experime
ntal animals was always less than that of controls (67 +/- 9% at postl
esion day 56). More axonal regeneration was seen in the hemiganglion i
psilateral to the branchial nerve. Regeneration after 32 days postlesi
on was 60 +/- 5% of controls in the ipsilateral hemiganglion, as oppos
ed to 29 +/- 6% in the contralateral hemiganglion. Regeneration of ind
ividual neurons was also demonstrated. Identified neuron R2 was shown
by intracellular dye injection and electrical stimulation of antidromi
c action potentials to have an axon in the branchial nerve in all gang
lia allowed to regenerate for longer than 32 days. These results indic
ate that in Aplysia, despite behavioral recovery, complete axonal rege
neration does not occur in a large segment of the neurons in the adult
central nervous system. (C) 1998 John Wiley & Sons, Inc.