Effects of forskolin, isoproterenol and lithium ions on leucophores of a teleost, Oryzias latipes: evidence for involvement of adenylate cyclase in pigment-dispersion response.

Forskolin, a stimulator of adenylate cyclase, induced a dose-dependent and reversible dispersion of pigment within fish leucophores. Li+, known as an inhibitor of the enzyme, depressed pigment-dispersion response of leucophores to either forskolin or isoproterenol, inducing an aggregation of pigment within the cells. These results indicate that Li+ acted on the cells through inhibition of forskolin- or isoproterenol-stimulated adenylate cyclase activity. The results suggest that adenylate cyclase is involved in the pigment-dispersion response of leucophores and that cAMP acts as a second messenger in the response.