Effects of melanocyte-stimulating hormone on wild-type and white axolotl neural crest cells.

The goals of the current research were twofold: to study the effects of melanocyte-stimulating hormone (MSH) on undifferentiated axolotl (Ambystoma mexicanum) neural crest cells and to determine whether wild-type or white mutant axolotl neural crest cells respond differently to MSH or to either of two agonists of the MSH signal transduction pathway (cholera toxin or N6,O2-dibutyryl adenosine 3',5'-monophosphate (dbcAMP). We found that MSH induces melanophore differentiation in axolotl neural crest cells in a dose-dependent manner; however, white, but not wild-type, neural crest cells are inhibited by the highest concentration of MSH (6 x 10(-6) M) tested. The effects of cholera toxin and dbcAMP indicate that the differentiation of melanophores from white neural crest cells may be more cAMP sensitive than wild-type neural crest cells. These results suggest that MSH is likely to play a regulatory role in the initial pigment pattern formation of wild-type and white axolotls.