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The
stress response elicited by shock delivery with an implantable cardioverter
defibrillator (ICD) has both a psychogenic component and a physical component.
Using this unique human stress paradigm, we plan to investigate whether
the psychogenic component (i.e., anticipating self-activation of the ICD
shock) releases oxytocin (OT) in men and women, a finding that has not
been demonstrated in humans. We will also determine the extent of
arginine vasopressin (AVP) release in response to the physical component
of the shock experience (i.e., shock delivery). Furthermore, we will
explore whether release of OT or AVP alters or modulates the adrenal response
to stress. We hypothesize that anticipation of shock delivery releases
OT in men and women, a finding that has not yet been demonstrated in humans,
whereas AVP release occurs immediately post shock in response to the intense
discomfort. We will test these hypotheses by analyzing serial blood
samples that have already been collected as part of a clinical study of
ICD shock experience. Both OT and AVP plasma concentrations will
be determined using in-house, state-of-the-art radioimmunoassay techniques.
Based on preliminary data, we expect to see varying degrees of OT release
prior to shock delivery which may be sustained after the shock is delivered
in some individuals. AVP should be consistently released to some
extent immediately after shock in all patients. Investigating the
neuroendocrine stress response in patients with ICDs is particularly important
because of the direct association between stress and cardiovascular disease.
Specifically, this study focuses on hormonal biomarkers which may modulate
anticipatory anxiety and physical stress related to the shock experience.
This knowledge will increase our understanding of the causal mechanisms
underlying the psychopathological sequelae of ICD therapy which may ultimately
translate into treatment strategies for clinical populations.
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