EFFECT OF THE NEUROTRANSMITTERS DOPAMINE, SEROTONIN AND NOREPINEPHRINE ON THE CILIARY ACTIVITY OF MUSSEL (MYTILUS-EDULIS) LARVAE

The acute and long-term effects of neurotransmitters dopamine (DA), serotonin (SE) and norepinephrine (NE) on the feeding rates of Mytilus edulis veliger larvae were investigated through concentration-response curves. Increasing DA concentrations increasingly inhibited food uptake. Acute exposure to high levels of DA caused long-term inhibitory effects on feeding rates (greater than or equal to 10(-5) MDA) and growth rates (greater than or equal to 3 x 10(-4) MDA). Feeding activity was also inversely related to NE concentration. SE concentrations between 10(-8)-3 x 10(-7) M supported enhanced feeding rates. Neither NE nor SE showed long-term inhibitory effects on feeding at concentrations < 10(-4) M. These results were consistent with the observed effects of the different neurotransmitters on the swimming pattern of the larvae. The experimental evidence supports the model of ciliary control in adult mussels, involving dual innervation of the ciliated cells of the velum, with excitatory serotonergic and inhibitory dopaminergic fibers.