Presence of Octopamine and an Octopamine Receptor in Crassostrea virginica.

Octopamine is a biogenic amine first identified in octopus. It has been well studied in arthropods and a few gastropods, serving as a neurotransmitter and hormone. The presence of octopamine has rarely been reported in bivalves and has not been reported in Crassostrea virginica. We utilized HPLC to identify and measure octopamine in cerebral ganglia, visceral ganglia, gill, palps, mantle, heart and hemolymph of C. virginica. Endogenous octopamine levels increased when animals were treated with tyramine, an octopamine precursor. A preliminary study in our lab found that octopamine has a cardio-excitatory action on C. virginica heart. In the present study we also used immunoblotting techniques to identify an octopamine-like receptor (Pan TAAR, trace amine-associated receptor) in oyster heart. The study confirms the presence of octopamine in the nervous system, innervated organs and hemolymph of C. virginica and identifies the presence of an octopamine-like receptor in heart, strengthening the contention that octopamine is important in the physiology of C. virginica as it is in other invertebrates.