Análise de biomarcadores morfológicos em girinos de rã-touro, Lithobates catesbeianus (Shaw, 1802), expostos a nanotubos de carbono de parede múltipla e ao seu surfactante isolado Pluronic TM F-127

Abstract

This work assessed the hepatic effect of carbon nanotubes (CNT) [10 mg.L-1] (NT group; n=9) associated with Pluronictm F-127 (0,1%), as well as its isolated effect (ST group; n=9), by the analysis of hepatic biomarkers in bullfrog tadpoles, Lithobates catesbeianus (SHAW, 1802), after 96h of exposure. The melanomacrophage cells area (A.MMC), sinusoidal area (A.SINUS), parenchymal area (A.HP), and the number of hepatocytes (C.HP) were assessed using hematoxylin-eosin (HE). The percentage of area occupied by lipids (A.SB) were assessed using a histochemistry technique (Sudan Black). We observed a reduction of the A.SINUS (P<0,001) for ST and NT groups compared to the CT group (n=9), as well as for the C.HP (P<0,001). In the latter, we also observed differences (P<0,001) between the ST and NT groups. For A.SB, were observed differences among all the groups (CT<ST, CT<NT, ST<NT). Our findings indicate that the reduction of A.SINUS (i.e., reduced hepatic vascularization) may trigger the cell death, leading to the C.HP reduction. The lower blood flux leads to lipidic cytoplasmic accumulation (hepatic steatosis), with increases in the A.SB and, hence, lead to the hepatocytes’ hypertrophy. However, the calculation of the IBR index (Integrated Biomarker Response) demonstrated that the A.SINUS was a very slight responsive biomarker. Therefore, the C.HP reduction should be associated with the synthesis of reactive oxygen species (ROS), which also leads to hepatic steatosis. This increases the A.SB, leading to cell death and to the reduction of the C.HP. Although future studies with distinct biomarkers are needed, the present study points to the urgency of the Brazilian regulating agencies to define safe normatives regarding the production and disposal of nanomaterials.