Octopamine and cyclic AMP stimulate protein phosphorylation in the central nervous system of Schistocerca gregaria

Abstract The effect of octopamine and cyclic AMP on the incorporation of 32 P into protein was studied in both intact and homogenized preparations of S. gregaria cerebral ganglia. Two criteria for incorporation were used; (i) the 32 P remaining in trichloroacetic acid-insoluble pellets after extraction with acidified chloroform/methanol and treated with ribonuclease (termed total protein), (ii) the 32 P bound to individual proteins was determined by solubilizing the proteins with SDS and separating them by polyacrylamide/SDS gel electrophoresis (termed specific protein). In intact ganglia octopamine stimulated an increased phosphorylation of total protein and that of a protein with a relative molecular weight of 39,000. Dibutyryl cyclic AMP also stimulated the phosphorylation of this protein in addition to at least seven other proteins. In homogenates octopamine also stimulated the phosphorylation of the 39,000 dalton protein as well as the phosphorylation of two other proteins ( M r 51,000 and 21,000). This occurred under conditions which favoured the prior elevation of cyclic AMP levels. Cyclic AMP stimulated an increased incorporation of 32 P into these proteins in addition to other proteins. These results indicate that cyclic AMP mediated protein phosphorylation may be involved in the physiological actions of octopamine in S. gregaria CNS.