Graduate Thesis Or Dissertation


The Effects of Heat-Killed Soil-Derived Saprophytic Bacterium Mycobacterium Vaccae on Stress-Induced Fear Behavior and Serotonergic Systems Public Deposited
  • The "Old Friends" hypothesis proposes that inflammatory diseases are increasing in modern urban societies, due in part to reduced exposure to microorganisms that drive immunoregulatory circuits and a failure to terminate inappropriate inflammatory responses. Inappropriate inflammation is also emerging as a risk factor for anxiety disorders, affective disorders, and trauma-and stressor-related disorders, including posttraumatic stress disorder (PTSD), which is characterized as persistent re-experiencing of the trauma after a traumatic experience. Traumatic experiences can lead to long-lasting fear memories and fear potentiation of the acoustic startle reflex. Mycobacterium vaccae is a soil-derived bacterium with anti-inflammatory and immunoregulatory properties that has demonstrated to increase stress resilience in a mouse model of PTSD. To determine if immunizations with M. vaccae NCTC 11659 also has protective effects in a fear-potentiated startle paradigm, male adult Sprague Dawley rats were immunized with M.vaccae (0.1 mg, s.c., in 100 uL borate-buffered saline) or vehicle. Additionally, we tested whether M. vaccae immunization given after fear conditioning would have protective effects in a fear-potentiated startle paradigm. Finally, it was determined if M. vaccae would also have protective effects in additional Pavlovian fear conditioning paradigms involving stress-induced exaggeration of fear and resistance to fear extinction. Together with previous studies, these data are consistent with the hypothesis that anti-inflammatory and immunoregulatory strategies, such as immunization with M. vaccae, have potential for both prevention and treatment of trauma- and stressor-related psychiatric disorders.

Date Issued
  • 2019
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Last Modified
  • 2019-12-19
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