DISASSEMBLY OF THE CHOLINERGIC POSTSYNAPTIC APPARATUS INDUCED BY AXOTOMY IN MOUSE SYMPATHETIC NEURONS - THE LOSS OF DYSTROPHIN AND BETA-DYSTROGLYCAN IMMUNOREACTIVITY PRECEDES THAT OF THE ACETYLCHOLINE-RECEPTOR
Ml. Zaccaria et al., DISASSEMBLY OF THE CHOLINERGIC POSTSYNAPTIC APPARATUS INDUCED BY AXOTOMY IN MOUSE SYMPATHETIC NEURONS - THE LOSS OF DYSTROPHIN AND BETA-DYSTROGLYCAN IMMUNOREACTIVITY PRECEDES THAT OF THE ACETYLCHOLINE-RECEPTOR, Journal of neuropathology and experimental neurology, 57(8), 1998, pp. 768-779
In mouse sympathetic superior cervical ganglion (SCG), cortical cytosk
eletal proteins such as dystrophin (Dys) and beta 1 Sigma 2 spectrin c
olocalize with beta-dystoglycan (beta-DG), a transmembrane dystrophin-
associated protein, and the acetylcholine receptor (AChR) at the posts
ynaptic specialization. The function of the dystrophin-dystloglycan co
mplex in the organization of the neuronal cholinergic postsynaptic app
aratus was studied following changes in the immunoreactivity of these
proteins during the disassembly and subsequent reassembly of the posts
ynaptic specializations induced by axotomy of the ganglionic neurons.
After axotomy, a decrease in the number of inh aganglionic synapses wa
s observed (t1/2 8 h 45'), preceded by a rapid decline of postsynaptic
specializations immunopositive for beta-DG, Dys, and alpha 3 AChR sub
unit alpha 3AChR (t1/2 3 h 45', 4 h 30' and 6 h, respectively). In con
trast, the percentage of postsynaptic densities immunopositive for bet
a 1 Sigma 2 spectrin remained unaltered. When the axotomized neurons b
egan to regenerate their axons, the number of intraganglionic synapses
increased,as did that of postsynaptic specializations immunopositive
for beta-DG, Dys, and alpha 3AChR. The latter number increased more sl
owly than that of Dys and beta-DG. These observations suggest that in
SCG neurons, the dystrophin-dystroglycan complex might play a role in
the assembly-disassembly of the postsynaptic apparatus, and is probabl
y involved in the stabilization of AChR clusters.