Independent roles of beta-adrenergic and glucocorticoid receptors in systemic and pulmonary effects of ozone
Citation:
Henriquez, A., S. Snow, Mette C. Schladweiler, C. Miller, AND U. Kodavanti. Independent roles of beta-adrenergic and glucocorticoid receptors in systemic and pulmonary effects of ozone. INHALATION TOXICOLOGY. Taylor & Francis, Inc., Philadelphia, PA, 32(4):155-169, (2020). https://doi.org/10.1080/08958378.2020.1759736
Impact/Purpose:
Dual therapy of beta adreneregic and glucocorticoid agonists is widely used for the treatment of chronic lung diseases such as asthma and COPD. When a systemic stress response is activated, a coordinated release of the stress hormones epinephrine followed by glucocorticoids (endogenous adrenergic and glucocorticoid receptor agonists, respectively) is necessary to orchestrate homeostatic metabolic and immunological changes. These data show that beta adrenergic receptors independent of glucocorticoid receptor participate in mediating ozone-induced inflammation and protein leakage. The systemic metabolic effects of ozone might be mediated by both receptor sub-types. Since these receptor types are extensively manipulated therapeutically, the potential air pollution drug interactions could exacerbate ozone/air pollution effects.
Description:
Background: The release of catecholamines is preceded by glucocorticoids during a stress response. We have shown that ozone-induced pulmonary responses are mediated through the activation of stress hormone receptors. Objective: To examine the interdependence of beta-adrenergic (βAR) and glucocorticoid receptors (GRs), we inhibited βAR while inducing GR or inhibited GR while inducing βAR and examined ozone-induced stress response. Methods: Twelve-week-old male Wistar-Kyoto rats were pretreated daily with saline or propranolol (PROP; βAR-antagonist; 10 mg/kg-i.p.; starting 7-d prior to exposure) followed-by saline or dexamethasone (DEX) sulfate (GR-agonist; 0.02 mg/kg-i.p.; starting 1-d prior to exposure) and exposed to air or 0.8 ppm ozone (4 h/d × 2-d). In a second experiment, rats were similarly pretreated with corn-oil or mifepristone (MIFE; GR-antagonist, 30 mg/kg-s.c.) followed by saline or clenbuterol (CLEN; β2AR-agonist; 0.02 mg/kg-i.p.) and exposed. Results: DEX and PROP + DEX decreased adrenal, spleen and thymus weights in all rats. DEX and MIFE decreased and increased corticosterone, respectively. Ozone-induced pulmonary protein leakage, inflammation and IL-6 increases were inhibited by PROP or PROP + DEX and exacerbated by CLEN or CLEN + MIFE. DEX and ozone-induced while MIFE reversed lymphopenia (MIFE > CLEN + MIFE). DEX exacerbated while PROP, MIFE, or CLEN + MIFE inhibited ozone-induced hyperglycemia and glucose intolerance. Ozone inhibited glucose-mediated insulin release. Conclusions: In summary, 1) activating βAR, even with GR inhibition, exacerbated and inhibiting βAR, even with GR activation, attenuated ozone-induced pulmonary effects; and 2) activating GR exacerbated ozone systemic effects, but with βAR inhibition, this exacerbation was less remarkable. These data suggest the independent roles of βAR in pulmonary and dependent roles of βAR and GR in systemic effects of ozone.
URLs/Downloads:
DOI: Independent roles of beta-adrenergic and glucocorticoid receptors in systemic and pulmonary effects of ozone