Pharmacology reveals neuropeptide Y as a novel differential regulator of adrenal steroids in the globally invasive red-eared slider turtle (Trachemys scripta elegans)

The regulation of adrenal steroid secretion during acute stress has been poorly explored in reptiles. Using pharmacological manipulations of adrenocorticotropic hormone (ACTH), dexamethasone (DEX), neuropeptide Y (NPY), and NPY receptor antagonists, we examined glucocorticoid and DHEA responses to identify pathways potentially linking stress adaptation and energy homeostasis in the red-eared slider (Trachemys scripta elegans). Acute handling stress increased corticosterone concentrations as did injection with ACTH, but NPY and receptor antagonist treatments prevented this endogenous increase in corticosterone. In contrast, cortisol, and DHEA were not impacted by handling stress or ACTH, but both steroids increased in response to injection with NPY and with an established Y2 receptor antagonist. Together these data reveal the possibility that both ACTH and NPY act to regulate adrenal steroid synthesis, through a complicated and currently poorly understood mechanism. As red-eared sliders are highly invasive on a global scale, these insights can enhance our understanding of reptilian stress physiology to inform management strategies as well as bridge the gap between fundamental biology and applied conservation efforts, demonstrating the broader value of integrative research in addressing ecological and biomedical challenges.