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.
Department of Applied Sciences for Biosystems, Section of Physiology and Human Nutrition, University of Cagliari, Via Porcell 4, Cagliari 09124, Italy.
M
M
Carta
M
M
Collu
F
F
Fadda
R
R
Stancampiano
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