Hj. Kim et al., AMOUNT OF SYMPATHETIC SPROUTING IN THE DORSAL-ROOT GANGLIA IS NOT CORRELATED TO THE LEVEL OF SYMPATHETIC DEPENDENCE OF NEUROPATHIC PAIN IN A RAT MODEL, Neuroscience letters, 245(1), 1998, pp. 21-24
Incomplete peripheral nerve injury often leads to neuropathic pains, s
ome of which are relieved by sympathectomy, and results in sympathetic
postganglionic nerve fiber sprouting in the dorsal root ganglion (DRG
). This study was performed to see whether the sprouting in the DRG pl
ays a key role in the sympathetic dependence of neuropathic pain. To t
his aim, we compared two groups of rats, both of which were subjected
to unilateral transection of the inferior and superior caudal trunks a
t the levels between the S1 and S2, S2 and S3, and S3 and S4 spinal ne
rves, with respect to sympathetic fiber sprouting; one group showed ne
uropathic pain behaviours (i.e. mechanical and cold allodynia signs) w
hich were very sensitive to phentolamine, alpha adrenergic blocker, an
d the other group exhibited no sensitivity. Immuno-histochemical stain
ing with tyrosine hydroxylase antibody or the S1-S3 DRGs was not corre
lated with the sensitivity to phentolamine. These results suggest that
the degree of sympathetic dependence of neuropathic pain is not a fun
ction of the extent of the sympathetic postganglionic nerve fiber spro
uting in the DRG. (C) 1998 Elsevier Science Ireland Ltd.