Differential effects of serotonergic and catecholaminergic drugs on ingestive behavior.
The serotonergic agonists fenfluramine and fluoxetine and the catecholaminergic agonists amphetamine and phenylpropanolamine are well known to cause a reduction in intake in rats. In the studies reported here we investigated the effects of these drugs on the microstructure of licking behavior of the rat ingesting 0.4 M sucrose. The purpose was to examine the similarities in the behavioral effects within and between these two classes of anorectic agents. The serotonergic agonists fenfluramine and fluoxetine caused a reduction in intake primarily by reducing the size of bursts and clusters of licking within the test meal without affecting the duration of the meal, suggesting a reduction in the palatability of the test solution. The catecholamine agonists amphetamine and phenylpropanolamine reduced intake primarily by reducing the number of bursts and clusters without affecting their size, suggesting a fractionation in the organization of the normal pattern of ingestion. The differences between the two serotonin and the two catecholamine agonists on the microstructure of the licking behavior suggest a different effect of the two neurotransmitters on the motor system that controls ingestive behavior. The similarities between the two different agonists within each class suggests a common neurotransmitter mechanism responsible for these two different effects on the behavior of the animals.
Abbott Laboratories, Neuroscience Research Division, Abbott Park, IL 60064.
K E
KE
Asin
J D
JD
Davis
L
L
Bednarz
D000818:Animals; D003913:Dextroamphetamine / Q000494:pharmacology; D004435:Eating / Q000187:drug effects*; D005277:Fenfluramine / Q000494:pharmacology; D005473:Fluoxetine / Q000494:pharmacology; D008297:Male; D010277:Parasympathomimetics / Q000494:pharmacology*; D010665:Phenylpropanolamine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*
D010277:Parasympathomimetics; D017366:Serotonin Receptor Agonists; D005473:Fluoxetine; D005277:Fenfluramine; D010665:Phenylpropanolamine; D003913:Dextroamphetamine