Identification of differentially expressed genes in dorsal root ganglia following partial sciatic nerve injury

Partial sciatic nerve injury, a model of neuropathic pain, elicits a variet y of neurochemical, electrophysiological and neuroanatomical changes in pri mary sensory neurons. We have used the technique of messenger RNA different ial display to identify genes with altered expression in these neurons whic h may contribute to the development of aberrant sensation following such pe ripheral nerve damage. This approach identified 14 distinct complementary D NA clones, representing transcripts with increased ipsilateral expression i n L4/5 dorsal root ganglia, two weeks after unilateral partial ligation of the rat sciatic nerve. Both Zucker diabetic fatty rats and their lean count erparts were used in this study but none of the transcripts identified show ed an induction that was confined to one of the two groups. The majority of the clones did not show significant sequence similarity to previously repo rted genes and therefore may represent novel messenger RNA sequences or, al ternatively, unknown regions of partially characterised messenger RNAs, Two of the clones represented transcripts for the known proteins muscle LIM pr otein and acidic epididymal glycoprotein, neither of which had previously b een associated with expression in the nervous system. Reverse transcriptase -polymerase chain reaction analysis and in situ hybridization confirmed tha t the messenger RNA expression of both muscle LIM protein and acidic epidid ymal glycoprotein was induced in an ipsilateral-specific manner. Their loca lisations, examined with in situ hybridization in L5 dorsal root ganglia, w ere limited in each case to a sub-population of neuronal profiles. Those ne uronal profiles that demonstrated muscle LIM protein hybridization were dis tributed across the profile size range, whereas the distribution of acidic epididymal glycoprotein-positive profiles appeared to be skewed towards sma ller profiles. The induction of muscle LIM protein and acidic epididymal glycoprotein in d orsal root ganglia may play an important functional role in the adaptive re sponse of primary sensory neurons following partial sciatic nerve injury. ( C) 1999 IBRO. Published by Elsevier Science Ltd.