Integrative Physiological Insights into Molecular Mechanisms of Stress Adaptation in Vertebrates

All vertebrates have evolved a highly sophisticated system of physiological and molecular responses to stress. Acute stress results in a fast neuroendocrine and autonomic activation, like HPA and SAM axes, cardiovascular changes, changes on respiratory function or metabolic alteration. Molecularly, stress activates heat shock proteins, mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K)/Akt signalling pathways, antioxidant responses and transcriptional and epigenetic programming. In contrast, chronic stress results in maintained elevation of glucocorticoids that modulate immunity, plasticity of behavior and cognition, structural remodeling of the nervous system, or developmental or reproductive adaptation. These interlocking systems reveal the vertebrate ability to cope in the short term and adaptively alter plasticity in the long run, weighing survival against potential physiological costs. An understanding of these mechanisms is key to the interpretation of stress responses in ecological, clinical and experimental research.