Repeated intranasal exposure to microcystin-LR affects lungs but not nasal epithelium in mice

Microcystin-LR (MC-LR) is a harmful cyanotoxin able to induce adverse outcomes in the respiratory system. We aimed to examine the lungs and nasal epithelium of mice following a sub-chronic exposure to MC-LR. Swiss mice were intranasally instilled with 10 mu L of distilled water (CTRL, n = 10) or 6.7 ng/kg of MC-LR diluted in 10 pi of distilled water (TOX, n = 8) during 30 consecutive days. Respiratory mechanics was measured in vivo and histology measurements (morphology and inflammation) were assessed in lungs and nasal epithelium samples 24 h after the last intranasal instillation. Despite the lack of changes in the nasal epithelium, TOX mice displayed an increased amount of PMN cells in the lungs ( x 10(-3)/mu m(2)), higher lung static elastance (cmH(2)O/mL), resistive and viscoelastic/inhomogeneous pressures (cmH(2)O) (7.87 +/- 3.78, 33.96 +/- 2.64, 1.03 +/- 0.12, 1.01 +/- 0.08, respectively) than CTRL (5.37 +/- 4.02, 26.65 +/- 1.24, 0.78 +/- 0.06, 0.72 +/- 0.05, respectively). Overall, our findings suggest that the nasal epithelium appears more resistant than lungs in this model of MC-LR intoxication. (C) 2015 Elsevier Ltd. All rights reserved.