effect of stress on levels of octopamine, dopamine and serotonin in the American cockroach (Periplaneta americana L.)

1. Various biogenic amines including octopamine, dopamine and serotonin, and their precursors and metabolites in haemolymph and the central nervous system from American cockroaches (Periplaneta americana L.) were measured using electrochemical detection.

2. Octopamine was found in similar high relative abundances in haemolymph and the central nervous system.

3. The amount of octopamine was much higher than that of tyramine and synephrine in haemolymph and thoracic nerve cord, whereas tyramine was at the highest level followed by octopamine and synephrine in the brain.

4. Insects were stressed by vibrating at 100 or 1000 Hz, visually by flashing light at 4 Hz for 15 min or by immersing the insect in water at 60°C for 30 sec, which resulted in the elevation of octopamine, tyramine, synephrine and tyrosine levels in thoracic nerve cord.