A physiological method to selectively decrease brain serotonin release.
In this protocol the effect of both an acute and chronic tryptophan (TRP)-free diet on brain serotonin (5-HT) release was studied in rats. Extracellular levels of cortical 5-HT, assessed by in vivo microdialysis, revealed a decrease in the release of this monoamine. Indeed, 120 min after the acute administration of a TRP-free diet, cortical 5-HT release decreased significantly by about 40% with respect to a balanced diet and the decrease persisted for more than 6 h. The chronic intake of a TRP-free diet induced a gradual reduction in 5-HT release. Five days after the diet consumption, our HPLC system detected no 5-HT in cortical dialysate. On the contrary, the acute or chronic administration of the TRP-free diet made no significant change in extracellular noradrenaline content in the frontal cortex, suggesting a specific action of the diet on the serotonergic system. Therefore, the administration of a TRP-free amino acid diet offers a non-pharmacological means for effectively decreasing brain 5-HT release. This diet can be used to study the physiological and behavioral effects of reduced brain 5-HT function.
Fadda
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F
Department of Applied Sciences for Biosystems, Section of Human Physiology, University of Cagliari, Via Porcell 4, I-09124, Cagliari, Italy. ffadda@vaxca1.unica.it
Cocco
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S
Stancampiano
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R
D000818:Animals; D001921:Brain / Q000378:metabolism*; D004032:Diet; D008297:Male; D017551:Microdialysis; D009446:Neurobiology / Q000379:methods*; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D012701:Serotonin / Q000378:metabolism*; D012726:Sexual Behavior, Animal / Q000187:drug effects; D014364:Tryptophan / Q000494:pharmacology*
D012701:Serotonin; D014364:Tryptophan; D009638:Norepinephrine