GAP-43, AFGF, CCK AND ALPHA-CGRP AND BETA-CGRP IN RAT SPINAL MOTONEURONS SUBJECTED TO AXOTOMY AND OR DORSAL-ROOT SEVERANCE

The mRNA levels for growth-associated protein 43 (GAP-43), acidic fibr oblast growth factor (aFGF), alpha- and beta-calcitonin gene-related p eptide (CGRP), cholecystokinin (CCK) and choline acetyltransferase (Ch AT) in rat lumbar spinal motoneurons were studied by in situ hybridiza tion 1, 5 and 21 days and 20 weeks following unilateral peripheral ner ve sectioning, ventral rhizotomy or dorsal rhizotomy. Furthermore, CGR P- and aFGF-like immunoreactivities in the ventral horn were studied u sing immunohistochemistry. One to 21 days after axotomy, GAP-43 and al pha-CGRP mRNAs increased in lesioned motoneurons, while the aFGF mRNA levels were marginally higher in motoneurons on the lesion side as com pared to the control side. Beta-CGRP, CCK and ChAT mRNA levels, on the other hand, decreased during the short-term response (1 - 21 days) to axotomy. After ventral rhizotomy, but not peripheral axotomy, there w as complete disappearance of aFGF-like immunoreactivity in the ventral root proximal to the lesion. In animals subjected to long-term surviv al (20 weeks) after peripheral axotomy, the expression of all studied substances had returned to normal levels. Unilateral dorsal rhizotomy did not induce any substantial short- or long-term shifts in the cellu lar expression of the GAP-43, aFGF, CGRP and CCK peptides or their mRN As in motoneurons of lesioned segments. These results indicate that pe ptides/proteins in motoneurons are expressed differentially after axot omy. Whereas alpha-CGRP and GAP-43 are up-regulated, CCK and beta-CGRP become down-regulated and aFGF is largely unaffected.