Amphetamine and reserpine deplete brain biogenic amines and alter blow fly feeding behavior.
HPLC with electrochemical detection was used to determine the levels of p-hydroxyphenylethanolamine (octopamine), 3,4-dihydroxyphenylethylamine (dopamine), and 5-hydroxytryptamine (5-HT) in the brains of control, reserpine, and d-amphetamine-treated blow flies, Phormia regina Meigen. Parallel studies were carried out to assess the effects of the two drugs on fly feeding behavior, measured as mean acceptance threshold: the minimum sucrose concentration to which the average fly in a population will respond by proboscis extension when its tarsi contact the solution. In saline-injected control flies, all three amines were found at levels of approximately 2 pmol/brain. Thirty minutes after injection with d-amphetamine (12 micrograms/fly), brain octopamine was depleted by 85%, whereas dopamine and 5-HT were depleted by 70%. Reserpine (5 micrograms/fly) caused 70% depletion of dopamine and greater than 90% depletion of both octopamine and 5-HT 24 h after injection. However, the effect of reserpine was much slower in onset (hours versus minutes) and more persistent (days versus hours) than was the effect of d-amphetamine. With either drug, the time course of amine depletion closely matched the time course of the increase in feeding threshold observed in drug-treated flies. These results suggest that CNS pools of the biogenic amines, octopamine, dopamine, and 5-HT are important in governing blow fly responsiveness to food stimuli.
D000588:Amines / Q000378:metabolism*; D000661:Amphetamine / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D004175:Diptera / Q000502:physiology*; D004298:Dopamine / Q000378:metabolism; D005247:Feeding Behavior / Q000187:drug effects; D007700:Kinetics; D009655:Octopamine / Q000378:metabolism; D012110:Reserpine / Q000494:pharmacology*; D012701:Serotonin / Q000378:metabolism
D000588:Amines; D009655:Octopamine; D012701:Serotonin; D012110:Reserpine; D000661:Amphetamine; D004298:Dopamine