Octopamine changes in nervous and non-nervous tissues of the locust, Locusta migratoria L., after different flight conditions

Abstract

1. After different durations of flight octopamine content was determined in nervous tissues—brain, optic lobes and metathoracic ganglia—and non-nervous tissues—hemolymph, flight muscles and fat body. 2. A single short 10 min flight resulted in an increase in octopamine in the optic lobes and metathoracic ganglia as well as in the hemolymph and fat body, whereas octopamine concentration decreased in brain and muscles. 3. Repeated 10 min flights resulted in an increase in octopamine in the brain, optic lobes and hemolymph with no change in metathoracic ganglia. Important decreases in the muscles were observed after repeated flights. 4. The use of inhibitors of dopa decarboxylase (RO 44602) or of dopamine β-hydroxylase (fusaric acid) resulted in an important octopamine decrease in nervous tissues. 5. Pretreatment with fusaric acid before flight was followed by the accumulation of p-tyramine in cephalic and metathoracic ganglia and to a lesser extent in the optic lobes suggesting an increased turnover of octopamine in these nervous tissues. 6. The tyramine concentration was either not detected in muscles or not significantly changed in hemolymph. 7. The origin of the high release of octopamine in hemolymph following short flight conditions is discussed.