Proceedings of The Physiological Society

Physiology 2016 (Dublin, Ireland) (2016) Proc Physiol Soc 37, PCA088

Poster Communications

Acute exposure to cylindrospermopsin: Pulmonary and cardiac outcomes after a 7-day treatment with anti-inflammatories

W. A. Zin1, P. A. Barboza1, G. C. Carvalho1, T. S. Almeida1, M. N. Machado1

1. Institute of Biophysics, Federeal University of Rio de Janeiro, Rio de Janeiro, RJ, Brazil.

INTRODUCTION: Cylindrospermopsin (CYN) is a cyanobacterial toxin of increasing worldwide environmental importance, as it can lead to disease if absorbed by human beings. LASSBio 596 (596) is a drug candidate with anti-inflammatory properties. We aimed at evaluating the lung and cardiac outcomes of a 7-day treatment with 596 or dexamethasone (DEX) of mice exposed to CYN. METHODS: The experiments were approved by the Ethics Committee on the Use of Animals in Scientific Experimentation, Health Sciences Center, Federal University of Rio de Janeiro (IBCCF Protocol 063/15). Male BALB/c mice (n=40) received by gavage distilled water (200 µl, n=18) or a sub-lethal dose of CYN (70 µg/kg in 200 µl of distilled water, n=22 (under isoflurane nasal cone anesthesia). 18 h later, the animals were gavaged under isoflurane anesthesia with either distilled water (200 µl) [groups CA (water+water, n=6) and CYNA (CYN+water, n=10)], or 596 (50 mg/kg by gavage) [groups CL (water+596, n=6) and CYNL (CYN+596, n=6)], or DEX (2 mg/kg by gavage) [groups CD (water+DEX, n=6) and CYND (CYN+DEX, n=6)]. Mice were treated every 12 h for 7 d. EKG was run before and after treatments. On the 8th day mice were sedated (diazepam, 5 mg, i.p.) and anesthetized (sodium pentobarbital, 20 mg/kg, i.p.), which maintains general anesthesia for at least 1 h, paralyzed (pancuronium bromide, 0.1 mg i.v.) and underwent mechanical ventilation. We measured pulmonary mechanics (6-10 cycles per animal) and EKG. The experiments lasted 15 min. The animals were quickly euthanized by sectioning of abdominal aorta and inferior vena cava after an extra shot of pentobarbital. Then, we fixed the left lungs for morphometric measurements, and homogenated the right lung for determination of inflammatory mediators IL-6, IL-1β, KC and TNF-α. Statistical analysis used one-way ANOVA, followed by Bonferroni's test when necessary, p<0.05 was considered statistically significant. Values are mean±SEM. RESULTS: EKG revealed a slower heart rate in CYN treated mice (CYNA: 467±25.85 vs. CA: 470±25.85; CYND 510±12.56 vs. CD 558±22.08; CYNL 571±15.98 vs. CL 596±17.70 bpm). TNF-α was higher in CYNA than in CA (205±34.34 vs. 113±3.89 pg/mg lung weight). CONCLUSIONS: The presently used dose of cylindrospermopsin, originally employed for intratracheal exposure, did not change either lung mechanics or morphology, but decreased heart rate in all intoxicated groups and increased TNF-α production solely in intoxicated, non-treated mice, suggesting that both dexamethasone and LASSBio 596 were able to block inflammation. Furthermore, possibly a higher oral dose would be required to trigger more serious outcomes.

Where applicable, experiments conform with Society ethical requirements