1. 5-HT2C Receptors in the BNST Modulate Contextual Fear Conditioning Without Affecting Acute Early Life Stress-Enhanced Fear Learning in Adult Rats
- Author
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Brianna L. Minshall, Catherine F. Wasylyshyn, Kate M. Brand, Caroline M. Bartoszek, Kennedy A. Seipel, Madeline M. Booms, Lucy C. Chappell, Amanda N. Reichert, Jacob R. Dowell, Angeles L. Buck, Henry T. Beckett, Christopher A. Lowry, and Jennifer J. Quinn
- Subjects
early-life stress ,post-traumatic stress disorder ,serotonin ,bed nucleus of the stria terminalis ,stress-enhanced fear learning ,SEFL ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Background/Objectives: Rodents provide a useful translational model of fear- and anxiety-related behaviors. Previously stressed animals exhibit physiological and behavioral stress responses that parallel those observed in anxious humans. Patients diagnosed with post-traumatic stress disorder (PTSD) present with a spectrum of debilitating anxiety symptoms that result from exposure to one or more traumatic events, with individuals exposed to early adverse experiences and women having increased vulnerability for diagnoses; however, the mechanisms of this increased vulnerability remain unknown. PTSD involves a complex network of highly interconnected brain regions, including the bed nucleus of the stria terminalis (BNST). Serotonin (5-HT) release into the BNST yields an increased expression of both fear and anxiety, specifically through 5-HT2C receptor signaling. The present experiment addressed whether 5-HT2C receptor signaling in the BNST is necessary for the acquisition of early-life stress (ELS)-induced enhancements in adult contextual fear learning. Methods: Rats received 0 or 15 footshocks on postnatal day 17, an established model of acute ELS (aELS) that yields enhanced adult fear learning. In adulthood, rats received bilateral infusions of a vehicle, a 5-HT2C receptor antagonist (RS-102221), or a 5-HT2C receptor agonist (MK-212) into the BNST 15 min prior to one-footshock contextual fear conditioning in a novel context. The next day, rats were returned to the fear-conditioning context to assess their fear memory (freezing). Results: Females demonstrated aELS-induced enhancement in contextual fear learning, while males did not. BNST infusions of RS-102221 reduced contextual fear conditioning, independent of aELS condition and sex. Infusions of MK-212 had no effect. Conclusions: Taken together, these data suggest that serotonergic signaling through 5-HT2C receptors in the BNST contributes to contextual fear conditioning, but not aELS-induced stress-enhanced fear learning (SEFL).
- Published
- 2024
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