Serotonin involvement in aversive conditioning: reversal of the fear retention deficit by long-term p-chloroamphetamine but not p-chlorophenylalanine.
5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT), a serotonin (5-HT) agonist, fenfluramine and p-chloroamphetamine (PCA), which are 5-HT releasers, produce deficits in fear retention as indicated by a notable lack of the immobility resulting from inescapable shocks. Depletion of central 5-HT neurones after long-term PCA treatment (2 X 10 mg/kg) completely blocked the retention impairment resulting from acute PCA (2.5 mg/kg) and fenfluramine (5 mg/kg), and partially blocked the deficit produced by 5-MeO-DMT (4 mg/kg). 5-HT depletion after p-chlorophenylalanine (PCPA) treatment (200, 100, 100 mg/kg, 72, 48 and 24 h before) did not do so; this is in agreement with other findings which suggest the involvement of different 5-HT stores in the action of PCA and PCPA. These data further underline the importance of the ascending 5-HT pathway in aversive conditioning in the rat.
D000662:Amphetamines / Q000494:pharmacology*; D000818:Animals; D001362:Avoidance Learning / Q000187:drug effects* / Q000502:physiology; D003213:Conditioning, Psychological / Q000187:drug effects* / Q000502:physiology; D004924:Escape Reaction / Q000187:drug effects; D005239:Fear / Q000187:drug effects* / Q000502:physiology; D010134:Fenclonine / Q000494:pharmacology*; D005277:Fenfluramine / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects*; D008732:Methoxydimethyltryptamines / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D012153:Retention, Psychology / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000502:physiology*; D010133:p-Chloroamphetamine / Q000494:pharmacology*
D000662:Amphetamines; D008732:Methoxydimethyltryptamines; D005277:Fenfluramine; D012701:Serotonin; D010133:p-Chloroamphetamine; D010134:Fenclonine