Alterações histológicas dos rins e expressão das metalotioneínas e das proteínas de choque térmico em ratos Wistar após exposição ao fungicida tirame

Abstract

The histological alterations and the expression of metallothionein (MTs) and heat shock protein (Hsp70) in the kidney of Wistar rats after thiram fungicide exposure were evaluated. Animals were distributed into three groups: standard diet group, standard diet + corn oil group and thiram group. Significant differences were found (P<0,05) in the evolution of body weight between rats in the thiram group and those in the control and corn oil groups, and no histological lesions were evident in the animals’ kidneys. Differences were found among animals in the group exposed to thiram and the control and oil groups regarding histomorphometric characteristics of the renal corpuscle – except for the proportion in the area of Bowman’s capsule: glomerulus area – and regarding the height of the epitelium in the distal tubules. In rats exposed to thiram, a positive moderate to strong immunoexpression was observed for MTs, in the cortical convulated tubules decreasing the cortex towards the medulla, and a strong immunoexpression for Hsp70 in the cortex and medulla areas, in the glomerulus and convulated tubules. The results suggest that thiram may have chronic toxicity in mammals affecting their growth, and that the expression of MTs and Hsp70, a probable cellular adaptive response to the oxidative stress caused by thiram, may be used as a biomarker of exposure to this chemical. Keywords: rat, kidney, thiram, histology, metallothioneins, heat shock proteins (Hsp70)