Behavioural neuroscienceMidazolam disrupts fear memory reconsolidation
Section snippets
Animals
Adult male Wistar rats provided by the Facultad de Veterinaria, Universidad Nacional de La Plata weighing 270–300 g at the start of the experiments were used. All animals were housed in standards laboratory Plexiglas cages in groups of three per cage at the animal colony of the Department of Pharmacology of the Facultad de Ciencias Químicas, and left without manipulation for 2 weeks for acclimation. Food and water were available ad libitum. Animals were maintained on a 12-h light/dark cycle
MDZ does not disrupt contextual fear memory when administered shortly following the training session
As can be seen in Fig. 1 rats that received systemic injection of MDZ displayed similar levels of freezing than animals injected with SAL immediately after conditioning. Analysis revealed no difference between the groups [F(1,20)=1.18, P=0.29].
MDZ disrupts contextual fear memory when given shortly after reminder
Fig. 2b and 2c depict freezing behavior assessed in animals whether subjected to the retrieval session or not. As shown in Fig. 2b both groups of rats (SAL and MDZ) showed a comparable freezing behavior during reactivation. Rats injected with MDZ shortly
Discussion
The main goal of the current study was to evaluate the effect of systemic MDZ administered after a reactivation procedure on the reconsolidation of a contextual fear memory. As expected, rats exposed to a context previously associated with footshock displayed considerable levels of freezing when exposed to test 1. These findings extend and confirm evidence from this and other laboratories demonstrating a reliable conditioned freezing response through the use of a contextual fear learning
Conclusion
In summary, the present data strongly suggest that BDZ administered shortly after the reactivation of an early fear memory with an appropriate cue (training context) disrupts memory reconsolidation. If these evidences are confirmed in humans, the reactivation of a “traumatic memory” through the presentation of a selective and appropriate cue could be susceptible of interference by BDZ compounds, becoming an additional tool for the treatment of patients which have experienced severe and
Acknowledgments
This work was supported by grants from SECyT, FONCyT, Agencia Córdoba Ciencia y CONICET to VAM. Thanks are extended to Dolores Trebucq for English technical assistance.
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