Morphological and histological abnormalities of the neotropical toad, Rhinella arenarum (Anura: Bufonidae) larvae exposed to dexamethasone

ANA PAULA CUZZIOL BOCCIONI; ., PELTZER, P.M., .; ATTADEMO A.M.,; MARTINUZZI C; LEON EJ; LAJMANOVICH, R.C.,

JOURNAL OF ENVIRONMENTAL SCIENCE AND HEALTH. PART B - PESTICIDES, FOOD CONTAMINANTS, AND AGRICULTURAL WASTES

TAYLOR & FRANCIS INC

Lugar: Londres; Año: 2021

0360-1234

Dexamethasone (DEX) is a glucocorticoid highly effective as an anti-inflammatory, immunosuppressantand decongestant drug. In the present study, a preliminary acute toxicity test wasassayed in order to determinate DEX median-lethal, lowest-observed-effect and the no-observedeffectconcentrations (LC50, LOEC and NOEC, respectively) on the common toad embryos (Rhinellaarenarum). Also, morphological and histological abnormalities from five body larval regions, livermelanomacrophages (MM) and glutathione S-transferase (GST) activity were evaluated in the toadlarvae to characterize the chronic sublethal effects of DEX (1?1,000 mg LL). Results of the acutetest showed that the LC50 of DEX at 96 h of exposure for the toad embryos (GS 18?20) was10.720mg Lg, and the LOEC was 1 mg Lg. In the chronic assay, the larval development and bodylength were significantly affected. DEX exposition also induced teratogenic effects. Most frequentexternal abnormalities observed in DEX-treated larvae included abdominal edema and swollenbody, abnormal gut coiling and visceral congestion. Intestinal dysplasia was recurrent in cross-sectionof all DEX-treated larvae. Neural, conjunctive and renal epithelial cells were also affected.Significant increase in liver MM number and size, and GST activity levels were also registered inDEX treatments with respect to controls. The evaluation of a variety of biomarkers provided clearevidence of toad larvae sensitivity to DEX, and the ecotoxicological risk of these pharmaceuticals,commonly found in different water bodies worldwide on aquatic animals.