No sympathetic nerve sprouting in rat trigeminal ganglion following painful and non-painful infraorbital nerve neuropathy

Following sciatic nerve injury sympathetic invasion acid basket formation i s seen in dorsal root ganglia. We examined whether this phenomenon occurs i n trigeminal ganglion (TG) following axotomy (IOA(x)) or chronic constricti on injury to the infraorbital nerve (IOCCI). The IOCCI rats developed hyper responsiveness to pinprick stimulation consistent with this model and the I OAx rats remained hyporesponsive for most of the study period. Immunocytoch emistry employing antibodies to tyrosine hydroxylase showed no sympathetic invasion or basket formation 2 and 7 weeks post surgery. This study confirm s previous work that found no sympathetic invasion of TG following injury, and shows that this finding is unaffected by the presence or absence of ner ve injury induced hyperresponsiveness. (C) 2001 Published by Elsevier Scien ce Ireland Ltd.