ALPHA-MSH BUT NOT ORG-2766 INDUCES EXPRESSION OF C-FOS IN CULTURED RAT SPINAL-CORD CELLS

Alpha-MELANOCYTE stimulating hormone (alphaMSH) and Org 2766 (an adren ocorticotrophic hormone (ACTH) MSH4-9 analogue) stimulate sprouting af ter nerve damage in vivo. in cultures of rat spinal cord cells only al phaMSH enhances neurite outgrowth. In order to analyse the mode of act ion of alphaMSH and to get a clue why its action differs from that of Org 2766, we studied whether expression of c-fos was induced in spinal cord cells by treatment with alphaMSH or Org 2766. We found a rapid a nd transient induction of both c-fos mRNA and protein after treatment with 100 muM alphaMSH. Treatment with Org 2766 (100 pM-100 muM) had no effect on c-fos expression. These results suggest that c-fos is invol ved in the signal transduction system of alpha-MSH stimulated neuronal outgrowth in vitro.