A tryptophan-free diet markedly reduces frontocortical 5-HT release, but fails to modify ethanol preference in alcohol-preferring (sP) and non-preferring (sNP) rats.
It has been hypothesised that rat lines genetically selected for their alcohol preference consume large amounts of ethanol because they have a low 5-HT content. Since brain tryptophan (TRP) availability controls the rate at which neurons synthesise and release serotonin (5-HT), we assessed whether the administration of a TRP-supplemented or TRP-free diet for 3 consecutive days influenced alcohol intake in alcohol-preferring and non-preferring sP and sNP rats, respectively. In the same animals extracellular 5-HT concentration was monitored by microdialysis in the frontal cortex. A TRP-free diet progressively and markedly decreased cortical extracellular 5-HT in sP and sNP rats during the treatment period with respect to a balanced diet. However, the TRP-free diet failed to modify alcohol consumption and preference in sP and sNP rats. The TRP-supplemented diet also failed to alter the intake of alcohol in either group of rats. Therefore, these results do not support a specific role of 5-HT transmission in ethanol intake and preference in sP and sNP rats.
Fadda
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F
Department of Biochemistry and Human Physiology, University of Cagliari, Italy. ffadda@vaxca1.unica.it
Cocco
S
S
Rossetti
Z L
ZL
Melis
G
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Stancampiano
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R
D000818:Animals; D002492:Central Nervous System Depressants / Q000378:metabolism*; D003259:Consummatory Behavior; D000431:Ethanol / Q000378:metabolism*; D005518:Food Preferences / Q000502:physiology*; D005625:Frontal Lobe / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D018377:Neurotransmitter Agents / Q000134:cerebrospinal fluid / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000134:cerebrospinal fluid / Q000378:metabolism*; D014364:Tryptophan / Q000008:administration & dosage / Q000378:metabolism*
D002492:Central Nervous System Depressants; D018377:Neurotransmitter Agents; D012701:Serotonin; D000431:Ethanol; D014364:Tryptophan