Glycosaminoglycan‐promoted muscle reinnervation and insulin‐like growth factor‐I levels are affected by anti‐growth hormone‐releasing hormone exposure

Abstract The present study shows that exposure to antibodies to growth hormone‐releasing hormone (GHRH) partially counteracted the promoting effects of treatment with glycosaminoglycans (GAGs) on muscle reinnervation. Sciatic nerve crush was performed in 2‐day‐old rats, and reinnervation of the extensor digitorum longus muscle was monitored. The extent of reinnervation was rather poor in saline‐treated rats, whereas in GAG‐treated rats the extent of muscle reinnervation, the recovery of nerve‐evoked muscle twitch tension, and the number of motor neurons reinnervating the extensor digitorum longus muscle were greatly enhanced. In addition, treatment with glycosaminoglycans increased markedly insulin‐like growth factor‐I (IGF‐I) levels in denervated muscles. Both types of stimulatory action exerted by GAGs were affected by concomitant exposure to anti‐GHRH, with abolition of IGF‐I muscle increase and a smaller enhancement in muscle reinnervation. J Neurosci. Res. 66:1112–1117, 2001. © 2001 Wiley‐Liss, Inc.