Caffeine can increase brain serotonin levels.
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D002110:Caffeine / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism; D051381:Rats; D012701:Serotonin / Q000378:metabolism*; D014364:Tryptophan / Q000378:metabolism
D012701:Serotonin; D002110:Caffeine; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan; D000242:Cyclic AMP