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

The present study shows that exposure to antibodies to growth hormone-relea sing hormone (GHRH) partially counteracted the promoting effects of treatme nt with glycosaminoglycans (GAGs) on muscle reinnervation. Sciatic nerve cr ush was performed in 2-day-old rats, and reinnervation of the extensor digi torum longus muscle was monitored. The extent of reinnervation was rather p oor in saline-treated rats, whereas in GAG-treated rats the extent of muscl e reinnervation, the recovery of nerve-evoked muscle twitch tension, and th e number of motor neurons reinnervating the extensor digitorum longus muscl e were greatly enhanced. In addition, treatment with glycosaminoglycans inc reased markedly insulin-like growth factor-I (IGF-I) levels in denervated m uscles. Both types of stimulatory action exerted by GAGs were affected by c oncomitant exposure to anti-GHRH, with abolition of IGF-I muscle increase a nd a smaller enhancement in muscle reinnervation. (C) 2001 Wiley-Liss, Inc.