Contrasting effects of diazepam and repeated restraint stress on latent inhibition in mice.
The effects on latent inhibition (LI; a delay in conditioning when a CS has been pre-exposed without consequences) of repeated restraint stress and the anxiolytic drug diazepam were examined in C57BL/6 mice to know whether previous aversive events or anxiolysis are factors determining the expression of LI. The LI model was optimized for this strain particularly sensitive to stress (using both the CER and the conditioned freezing procedures) and characterized with typical (haloperidol) and atypical (clozapine and olanzapine) antipsychotic drugs administered either during the conditioning or the pre-exposure phases. An acute challenge with amphetamine, a dopamine releaser, was done to verify the enhancement of hyperactivity in C57BL/6 mice after the restraint stress sensitization. At all doses tested, diazepam decreased latent inhibition when administered during the pre-exposure phase (similarly to atypical antipsychotic drugs). Repeated restraint stress enhanced LI by blocking the CS-induced freezing in pre-exposed mice. In contrast, pre-treatment with diazepam before pre-exposure allowed the expression of CS-induced freezing in stressed mice pre-exposed to the tone. It is suggested that stress and anxiolytic drugs can have opposite effects on attention or perseveration processes during learning of conflicting contingency responses.
Mongeau
Raymond
R
Neuroscienze PharmaNess S.c.a.r.l., Scientific and Technological Park of Sardinia, ma c/o Sardegna Ricerche, Ed.5, Loc.Piscinamanna, 09010 Pula (CA), Italy. raymond.mongeau@chups.jussieu.fr
Marcello
Stefania
S
Andersen
Jacob Sparre
JS
Pani
Luca
L
D000661:Amphetamine / Q000494:pharmacology; D000818:Animals; D014151:Anti-Anxiety Agents / Q000627:therapeutic use*; D014150:Antipsychotic Agents / Q000494:pharmacology; D001522:Behavior, Animal / Q000187:drug effects; D000697:Central Nervous System Stimulants / Q000494:pharmacology; D003213:Conditioning, Psychological / Q000187:drug effects; D003975:Diazepam / Q000627:therapeutic use*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004644:Emotions / Q000187:drug effects; D005239:Fear; D046352:Freezing Reaction, Cataleptic / Q000187:drug effects; D006220:Haloperidol / Q000494:pharmacology; D007266:Inhibition, Psychological; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012149:Restraint, Physical / Q000379:methods; D013315:Stress, Psychological / Q000188:drug therapy* / Q000209:etiology / Q000523:psychology
D014151:Anti-Anxiety Agents; D014150:Antipsychotic Agents; D000697:Central Nervous System Stimulants; D000661:Amphetamine; D006220:Haloperidol; D003975:Diazepam