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Effects of Essential Oil on Fear Memory and the Immune Response: A Potential Alternative Therapy for Post Traumatic Stress Disorder (PSTD)
Author(s) -
Moshfegh Cassandra,
Swiercz Adam P,
Hopkins Lauren,
Hurr Chansol,
Young Colin N,
Marvar Paul J
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.882.5
Subject(s) - immune system , fear conditioning , freezing behavior , extinction (optical mineralogy) , inflammation , medicine , conditioning , psychology , immunology , psychiatry , anxiety , biology , statistics , mathematics , paleontology
Chronic stress plays an integral role in activation and exacerbation of inflammation in the peripheral immune system. Peripherally circulating immune cells are also capable of crossing the blood‐brain barrier and can promote inflammation in the central nervous system (CNS), which has been suggested to contribute to mental health disorders, such as post traumatic stress disorder (PTSD). However, the association between fear memory and the immune system is not well characterized. Moreover, there are only two FDA‐‐approved medications currently for PTSD. Therefore we sought to examine orange essential plant oil (OEPO), previously been found to have CNS depressant‐‐like effects, on fear memory and immune cell activation in a mouse model of PTSD (Pavlovian Fear Conditioning). The treatment group (n=8) was administered 25% OEPO via olfactory exposure prior to and after fear conditioning. Mice exposed to 25% OEPO showed no difference in percent freezing during fear acquisition compared to controls. However, when tested for extinction retention 48 hours later the treatment group experienced a significant decrease in freezing behavior (17.1 ± 1.6 % (p < 0.01) versus control (3.67 ± 2.13%), suggesting that OEPO affects extinction of fear memory in mice. Next we examined the peripheral and central immune response following extinction of fear memory using flow cytometry analysis. A significant decrease in the number of effector memory T cells CD62loCD44hi 7.955(± 0.48)% was observed in the treatment group relative to control 12.05(± 0.708)% (p < 0.05). To evaluate the effect of OEPO on the central immune response, we performed an immunological challenge with intraperitoneal injected lipopolysaccharide (LPS) and assessed immune cell populations in the meningeal compartment. Our preliminary evidence suggest that LPS injected mice treated with OEPO for 2hrs have decreased CD45+CD11b+ cells 54.2% compared to LPS injected mice treated with water 68.7%. These data suggest that OEPO may modulate the neuroimmune response during fear memory recall. Further studies are required to determine the neuroimmune mechanism(s) responsible for the extinction of fear memory in OEPO treated mice. Support or Funding Information NIH R00 HL107675‐‐03