The relation between cerebral serotonin levels and conditioned behaviour in the rat following the administration of LSD-25 and UML.
Successive daily injections of LSD-25 and UML (1-methyl-d-lysergic acid butanolamide) caused progressive depression of brain 5-HT levels in the rat.  On the fourth day, the decrease was significant with respect to the highly significant fall observed after a single administration, whereas it had been shown earlier that conditioned behaviour is no longer affected by LSD-25 after 3 days and that simultaneous administration of a single dose of LSD-25 and UML is equally ineffective in this respect.  Its depression of 5-HT levels, however, has now been shown to be equal to that of LSD-25 alone at doses that influence conditioned behaviour.  The findings indicate that changes in such behaviour are not dependent on brain 5-HT levels and that no link exists between such levels and the psychotomimetic effect of LSD-25 in man.
D000818:Animals; D001923:Brain Chemistry / Q000187:drug effects*; D003213:Conditioning, Psychological / Q000187:drug effects*; D003864:Depression, Chemical; D004305:Dose-Response Relationship, Drug; D007274:Injections, Intraperitoneal; D008238:Lysergic Acid Diethylamide / Q000008:administration & dosage / Q000494:pharmacology*; D008297:Male; D008784:Methysergide / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D012701:Serotonin / Q000032:analysis*; D013997:Time Factors
D012701:Serotonin; D008238:Lysergic Acid Diethylamide; D008784:Methysergide