Key result
Extinction training significantly attenuated the conditioned mean arterial pressure response to a conditioned stimulus in fear-conditioned mice compared to no extinction training (106 vs 122 mmHg, p<0.05).
Why the study?
Does extinction training attenuate conditioned cardiovascular fear reactivity (MAP and HR responses) in fear-conditioned mice?
Does extinction training attenuate conditioned cardiovascular fear reactivity (MAP and HR responses) in fear-conditioned mice?
Absolute Event Rate: 106% vs 122%
p-value: p=<0.05
Extinction learning in a mouse model attenuates acute mean arterial pressure responses to conditioned fear stimuli, suggesting a potential mechanism to mitigate cardiovascular risk in PTSD.
Extinction training merits testing in cardiovascular PTSD models; leaves open translation from this mouse evidence.
Post-traumatic stress disorder (PTSD) is characterized by a heightened emotional and physiological state and an impaired ability to suppress or extinguish traumatic fear memories. Exaggerated physiological responses may contribute to increased cardiovascular disease (CVD) risk in this population, but whether treatment for PTSD can offset CVD risk remains unknown. To further evaluate physiological correlates of fear learning, we used a novel pre-clinical conditioned cardiovascular testing paradigm and examined the effects of Pavlovian fear conditioning and extinction training on mean arterial pressure (MAP) and heart rate (HR) responses. We hypothesized that a fear conditioned cardiovascular response could be detected in a novel context and attenuated by extinction training. In a novel context, fear conditioned mice exhibited marginal increases in MAP (∼3 mmHg) and decreases in HR (∼20 bpm) during CS presentation. In a home cage context, the CS elicited significant increases in both HR (100 bpm) and MAP (20 mmHg). Following extinction training, the MAP response was suppressed while CS-dependent HR responses were variable. These pre-clinical data suggest that extinction learning attenuates the acute MAP responses to conditioned stimuli over time, and that MAP and HR responses may extinguish at different rates. These results suggest that in mouse models of fear learning, conditioned cardiovascular responses are modified by extinction training. Understanding these processes in pre-clinical disease models and in humans with PTSD may be important for identifying interventions that facilitate fear extinction and attenuate hyper-physiological responses, potentially leading to improvements in the efficacy of exposure therapy and PTSD-CVD comorbidity outcomes.
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Swiercz et al. (2018) studied Fear conditioning (PTSD model). Extinction training vs. No extinction training was evaluated on Peak mean arterial pressure (MAP) during conditioned stimulus presentation after extinction training (p=<0.05). Extinction training significantly attenuated the conditioned mean arterial pressure response to a conditioned stimulus in fear-conditioned mice compared to no extinction training (106 vs 122 mmHg, p<0.05).
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