TIME-COURSE OF DEGENERATIVE AND REGENERATIVE CHANGES IN THE DORSAL HORN IN A RAT MODEL OF PERIPHERAL NEUROPATHY

The time course of histochemical changes in the dorsal horn of rats su bjected to an experimental peripheral neuropathy has been examined. Qu alitative and quantitative analyses of the changes in dorsal horn stai ning were made for soybean agglutinin (SBA)-binding glycoconjugates, t he soluble lectins RL-14.5 and RL-29, the growth-associated protein (G AP)-43, and the neuropeptides substance P (SP) and calcitonin gene-rel ated peptide (CGRP). These analyses were made at various time points a fter chronic constriction of the sciatic nerve. Quantitative analysis indicated that staining density increased in the normal territories st ained fur SBA-binding glycoconjugates, RL-14.5, RL-29, and GAP-43 on t he neuropathic side compared with the control side. In addition, there was an extension of the territories stained for SEA-binding glycoconj ugates and RL-29 ipsilateral to the injury The peak increases occurred at 14 or 28 days, followed by a decrease toward control levels by 70 days. In contrast, the staining density for SP in the ipsilateral dors al horn decreased at 3 and 5 days and reached a peak decrease at 14 da ys. Then, the staining for SP returned toward control values. The stai ning or CGRP was unchanged at all time points examined. Dorsal rhizoto mies ipsilateral to the nerve injury in neuropathic rats indicated tha t the increases in staining were attributable to changes in primary af ferent neurons. These data suggest that peripheral neuropathy causes c omplex degenerative and regenerative changes in the central branches o f primary afferent neurons. The associated synaptic reorganization may contribute to the sensory abnormalities that accompany peripheral neu ropathy. (C) 1997 Wiley-Liss, Inc.