Augmented cocaine-induced accumbal dopamine efflux, motor activity and place preference in rats fed with a tryptophan-deficient diet.
In the present study we demonstrate that consumption of a tryptophan-deficient diet for a period of 14 days decreased the striatal serotonin and 5-hydroxyindolacetic acid tissue content in rats, whereas the level of dopamine remained unchanged. Under this condition of diminished serotonergic tone, a challenge dose of cocaine (10mg/kg, i.p.) significantly increased motor activity and dopamine extracellular content in the nucleus accumbens compared to rats fed with a balanced diet. We moreover found that pretreatment with cocaine (7 and 10mg/kg, i.p.) produced a significant increase in preference for a cocaine-associated environment in the tryptophan-deficient group compared to control rats. Our experiments show that a low tone of serotonergic system, augments the behavioural reinforcing effect of cocaine and that this effect may be due to a increased cocaine-induced accumbal dopamine release. These data indicate that a tryptophan-deficient diet alters the behavioural and neurochemical effect of psychostimulants, such as cocaine, and suggest an important role of serotonin in modulation of these effects.
Carta
M
M
Department of Applied Sciences for Biosystems, Section of Physiology and Human Nutrition, University of Cagliari, Via Porcell 4, Cagliari 09124, Italy.
Collu
M
M
Fadda
F
F
Stancampiano
R
R
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D003042:Cocaine / Q000378:metabolism / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000378:metabolism / Q000503:physiopathology; D004195:Disease Models, Animal; D004298:Dopamine / Q000378:metabolism*; D004780:Environment, Controlled; D005106:Exploratory Behavior / Q000187:drug effects / Q000502:physiology; D045604:Extracellular Fluid / Q000187:drug effects / Q000378:metabolism; D005526:Food, Formulated; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D006948:Hyperkinesis / Q000139:chemically induced / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology; D009714:Nucleus Accumbens / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000096:biosynthesis*; D014364:Tryptophan / Q000172:deficiency*
D012701:Serotonin; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D003042:Cocaine; D004298:Dopamine