Potential Mechanisms Underlying the Facilitation of Fear Memory Extinction by Cotinine
Valentina Echeverria *
Research and Development Service, Department of Veterans Affairs, Bay Pines VA Healthcare System, Bay Pines Florida 33744, USA and Research Service, Department of Veterans Affairs, Tampa, Florida 33612, USA and Department of Molecular Medicine, University of South Florida, Tampa, Florida 33647, USA.
Alex Iarkov
Research and Development Service, Department of Veterans Affairs, Bay Pines VA Healthcare System, Bay Pines Florida 33744, USA.
*Author to whom correspondence should be addressed.
Abstract
Posttraumatic stress disorder is a type of anxiety disorder that manifests after exposure to a traumatic event that was perceived as life threatening. Individuals with posttraumatic stress disorder have a deficiency in the extinction of fear memory. Moreover, environmental cues similar to the ones present during the trauma induced abnormal symptoms of fear and anxiety. Current therapies only help a small percentage of patients with this condition, thus pharmacological interventions to reduce the conditioned fear response are needed. Nicotine and its main metabolite, cotinine, have been shown to help in the extinction of fear memories in animal models. In this article we will discuss potential mechanisms and brain regions that may be underlying the effect of cotinine in enhancing the extinction of fear response after fear conditioning. The relevance of these mechanisms in posttraumatic stress disorder is discussed.
Keywords: Tobacco smoking, fear conditioning, trauma, anxiety, depressive-like behavior