Amphetamine and Reserpine Deplete Brain Biogenic Amines and Alter Blow Fly Feeding Behavior

Abstract

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.

Development of an identified serotonergic neuron in the antennal lobe of the moth and effects of reduction in serotonin during construction of olfactory glomeruli

“…Other pharmacological agents commonly used in vertebrates for 5-HT depletion, for example, pchlorophenylalanine, reserpine, and 5,7-dihydroxytryptamine, were not tried. The selectivity and efficacy of these agents when used in insects varies widely (Omar et al, 1982;Sloley and Owen, 1982;Pandey et al, 1983;Brookhart et al, 1987). Also, when these agentsdo cause a depletion of CNS 5-HT in invertebrate preparations, in most cases it is a partial and short-term depletion, not the total depletion for the long durations needed for our experiments in Mundzica (Glover and Kramer, 1982;Lent and Dickinson, 1984;Murphy et al, 1984;Nassel and Elekes, 1985;Gadotti et al, 1986;Orchard, 1990, 1993).…”

Octopamine mediates rapid stimulation of protein kinase A in the antennal lobe of honeybees

“…Reserpine interferes with the vesicular uptake of monoamines in nerve terminals and has been widely used to block neurotransmission by monoamines. In the blowfly, reserpine decreases the brain level of octopamine more readily than that of dopamine or serotonin (Brookhart et al, 1987). Applied to the honeybee, immunohistochemical methods showed that reserpine reduces monoamines in the brain below detection levels (Braun and Bicker, 1992).…”

“…Reserpine depletes the brain of monoamines (Brookhart et al, 1987;Braun and Bicker, 1992). The strong reduction in the intensity of the proboscis extension response to sucrose solution caused by reserpine (Braun and Bicker, 1992) was used to monitor the success of this treatment.…”

Efectos de reserpina y p-cloranfetamina en el metabolismo y la liberación de 5-HT en el ganglio cerebral de Inachis io (Lepidoptera).

“…It is well known that reserpine administration in mammals reduces the levels of brain amines (39), leading to characteristic alterations in behaviour. Several studies in insects indicate that reserpine also non-specifically reduces the levels of serotonin, octopamine and dopamine from the central nervous system (5,20,41,46). PCA is a potent neurotoxin which has been shown to induce rapid release and depletion of 5-HT in the brain of rats (48).…”