Date Thesis Awarded


Access Type

Honors Thesis -- Access Restricted On-Campus Only

Degree Name

Bachelors of Science (BS)




Joshua A. Burk

Committee Members

Shanta D. Hinton

Claire McKinney


Background – PTSD is a chronic and debilitating mental illness with limited available treatments. New medications, including Angiotensin Type 1 Receptor inhibitors, have been found to improve extinction learning retention in rodents and could be a means of improving the efficacy of exposure and cognitive based therapies for PTSD and other anxiety related disorders. Studies of new medications use an ideal model of extinction that does not mirror the inconsistencies of human therapy and recovery. The present experiment attempted to model the inconsistent nature of exposure therapy and examine whether the AT1R inhibitor, losartan, would still improve extinction learning.

Methods – Using the fear-potentiated startle paradigm as an extinction paradigm, the study investigated whether acute treatment with losartan, an angiotensin type 1 receptor inhibitor, could still augment extinction retention. Following Pavlovian fear conditioning, an animal model for PTSD, subjects were treated to losartan and tested for extinction learning over the course of two days.

Results – Groups treated with losartan showed consistent significant fear-potentiated startle in both tests following initial fear conditioning. In contrast, groups treated with saline did not show significant changes in fear-potentiated startle or trend towards a significant increase in startle reactivity on either day.

Conclusions – The significant increase exhibited by the group treated with losartan could be an implication that losartan could augment fear memory as well as extinction retention, but further study will be necessary to confirm whether the Fear-Potentiated Startle paradigm can truly demonstrate fear extinction in animals.

On-Campus Access Only