Neuroendocrine Contribution to Sex-Related Variations in Adverse Air Pollution Health Effects
Air pollution exposure is ranked as a leading environmental risk factor for adverse health effects. Current evidence links some air pollution health outcomes with activation of neuroendocrine sympathetic-adrenal-medullary and hypothalamic-pituitary-adrenal (HPA) stress axes, and resultant increases in adrenal-derived stress hormones as circulating mediators of multi-organ stress reactions. Epidemiological and experimental investigations also demonstrate sex-specific responses to air pollutant inhalation, which may be explained by hormonal interactions within the stress and reproductive axes. Sex hormones (androgens and estrogens) interact with neuroendocrine functions to influence hypothalamic responses, subsequently augmenting stress-mediated metabolic and immune changes. This neurohormonal interactions likely contributes to innate sex-specific responses to inhaled irritants, causing differing individual susceptibility. In this review, we discuss: 1) neuroendocrine co-regulation of the HPA axis by gonadal hormones, 2) experimental evidence demonstrating sex-specific respiratory and systemic effects of air pollutant inhalation, and 3) proposed mechanisms of stress and sex hormone interactions during air pollution-related stress.