Pesticide Dichlorvos Promotes Morphological Alternations in the Rat Prostate

Abstract

The complex process of carcinogenesis can be modulated by the action of environmental endocrine disruptors, such as the organophosphate pesticide Dichlorvos (DDVP), capable of interfering in homeostasis of different organs and leading to the development of neoplastic lesions. Considering that prostate cancer is the second most common neoplasm in men, worldwide, it is emphasized the importance of studying morphological alterations using animal models. In rodents, tumor initiation can be induced by the carcinogen N‐methyl‐N‐nitrosourea (MNU) and tumor promotion can be stimulated by the administration of testosterone, combinated or not with the use of pesticides. The present study aimed to evaluate the influence of DDVP on the development of morphological alterations in the ventral prostate of rats, after chemical induction by MNU. Thereunto, 32 Fischer 344 rats, aged 90 days, were randomly separated into four experimental groups: Control, DDVP, MNU, MNU+DDVP. For chemical induction, the MNU and MNU+DDVP groups were inoculated with MNU (15 mg/kg), followed by daily subcutaneous injections of testosterone cypionate (2.5 mg/kg), for 20 days. Animals of the DDVP and MNU+DDVP groups, from 120 to 240 days old, received the basal diet supplemented with 10 mg/kg of DDVP. Subsequent to the experimental period, the prostatic ventral lobe of each animal was collected and subjected to morphometric‐stereological and histopathological analysis, for the classification of the lesions found. The incidence of alterations in epithelium and stroma of all experimental groups was evaluated, such as epithelial hyperplasia (increased cell population with stratification, without atypia) (Figure A and B); atrophy (retraction of the epithelium with reduction of the secretory cytoplasm) (Figure C and D); periacinary inflammatory foci (presence of inflammatory cell infiltrate) (Figure E and F); cell atypia with presence of cytoplasmic inclusions (Figure G and H) and metaplasia with stromal hyperplasia (change in the pattern of the original epithelium without proliferative change, with an increase in the adjacent stroma) (Figure I to L). The results showed a significant increase of epithelial hyperplasia areas in MNU and MNU+DDVP groups, with 100% of the animals showing this lesion (Table 1), which demonstrates a relation between chemical induction and the proliferative process. The morphometric‐stereological analysis confirmed this finding, revealing a relatively greater volume of the epithelial compartment in MNU+DDVP, compared to the Control group (Table 2). Thus, it can be concluded that DDVP, even in low concentration, associated with chemical induction by MNU, was able to disturb the morphology of the ventral prostate, promoting proliferative epithelial lesions, strongly associated with the process of carcinogenesis.