SYNTHESIS AND CONTENT OF NEUROTRANSMITTERS AND THEIR EFFECT ON CYCLIC NUCLEOTIDE ACCUMULATION IN THE CENTRAL NERVOUS-SYSTEM OF MANDUCA-SEXTA

In this study the ability of the intact nerve cord of Manduca sexta to synthesize 5-hydroxytryptamine (serotonin) and acetylcholine from labelled precursors is shown. The endogenous levels of amino acids in haemolymph and nervous tissue and the levels of dopamine, norepinephrine, 5-hydroxytryptophan and 5-hydroxytryptamine are presented. The accumulation of cyclic AMP and cyclic GMP in nerve cords from Manduca sexta was investigated after in vitro incubation in solutions containing putative neurotransmitters. Basal cyclic AMP levels were in agreement with results of other workers using insect systems. Serotonin elevated cyclic AMP levels. Acetylcholine and the amino acids aspartate, glutamate, glycine and γ-aminobutyrate, elevated cyclic GMP levels. These results support roles for serotonin and acetylcholine in neuronal function mediated by cyclic AMP and cyclic GMP, respectively. © 1979.