RATIONALE: We have recently shown that post-extinction exposure of rats to a sub-threshold reminder shock can reactivate extinguished context-related freezing and found that chronic treatment with fluoxetine before fear extinction prevents this phenomenon. OBJECTIVES: In the present study, we examined whether these findings would be confirmed with auditory fear conditioning. METHODS: Rats were initially submitted to a session of five tone-shock pairings with either a 0.7- or 0.1-mA shock and underwent, 3 days later, a session of 20 tone-alone trials. RESULTS: At the beginning of this latter session, we observed cue-conditioned freezing in rats that received the strong, but not the weak, shock. At the end, both groups (strong and weak shocks) displayed similar low levels of freezing, indicating fear extinction in rats exposed to the strong shock. These rats exhibited again high levels of cue-evoked freezing when exposed to three tone-shock pairings with 0.1-mA shock. This reemergence of cue-conditioned fear was completely abolished by chronic (over a 21-day period) fluoxetine treatment which spared, when administered before the initial fear conditioning, the original tone-shock association. CONCLUSIONS: These data extend our previous findings and suggest that chronic fluoxetine treatment favor extinction memory by dampening the reactivation of the original tone-shock association.
RATIONALE: We have recently shown that post-extinction exposure of rats to a sub-threshold reminder shock can reactivate extinguished context-related freezing and found that chronic treatment with fluoxetine before fear extinction prevents this phenomenon. OBJECTIVES: In the present study, we examined whether these findings would be confirmed with auditory fear conditioning. METHODS:Rats were initially submitted to a session of five tone-shock pairings with either a 0.7- or 0.1-mA shock and underwent, 3 days later, a session of 20 tone-alone trials. RESULTS: At the beginning of this latter session, we observed cue-conditioned freezing in rats that received the strong, but not the weak, shock. At the end, both groups (strong and weak shocks) displayed similar low levels of freezing, indicating fear extinction in rats exposed to the strong shock. These rats exhibited again high levels of cue-evoked freezing when exposed to three tone-shock pairings with 0.1-mA shock. This reemergence of cue-conditioned fear was completely abolished by chronic (over a 21-day period) fluoxetine treatment which spared, when administered before the initial fear conditioning, the original tone-shock association. CONCLUSIONS: These data extend our previous findings and suggest that chronic fluoxetine treatment favor extinction memory by dampening the reactivation of the original tone-shock association.
Authors: E Cavazzuti; A Bertolini; A V Vergoni; R Arletti; R Poggioli; A Forgione; A Benelli Journal: Psychopharmacology (Berl) Date: 1999-03 Impact factor: 4.530
Authors: Catherine A Hartley; Morgan C McKenna; Rabia Salman; Andrew Holmes; B J Casey; Elizabeth A Phelps; Charles E Glatt Journal: Proc Natl Acad Sci U S A Date: 2012-03-19 Impact factor: 11.205
Authors: N C R McLaughlin; D Strong; A Abrantes; S Garnaat; A Cerny; C O'Connell; R Fadok; C Spofford; S A Rasmussen; M R Milad; B D Greenberg Journal: Behav Brain Res Date: 2014-11-12 Impact factor: 3.332
Authors: Paul J Fitzgerald; Nigel Whittle; Shaun M Flynn; Carolyn Graybeal; Courtney R Pinard; Ozge Gunduz-Cinar; Alexxai V Kravitz; Nicolas Singewald; Andrew Holmes Journal: Neurobiol Learn Mem Date: 2013-11-11 Impact factor: 2.877