Figure 5

Effect of α2 ADR agonist and antagonist on light-induced swimming response in C. intestinalis larva. Muscle field potentials are recorded from the larval tail (see Methods) as an index of its contractile states. Response of Ciona larva to a five-second exposure to dark in control (upper trace), drug-treated (middle trace), and washed (lower trace) preparations are shown for fluoxetine (20 μM, left panel), dexmetedomidine (middle panel) and atipamizole (right panel). The blocking effect on light-off induced swimming of fluoxetine, is reproduced by the ADRα2 antagonist, whereas the ADRα2 agonist had an opposite effect, suggesting these receptors are mediating the effect of released monoamines (probably DA) on the photomotor response. These are representative example of all the experiments we have performed (n = 5 to 10 depending on the drug used).