Simulação de pulverização ambiental de herbicidas e seus efeitos reprodutivos masculinos em modelo animal

Abstract

The herbicides 2,4-D (dichlorophenoxyacetic acid) and glyphosate (N-phosphonomethyl-glycine) are widely used in agriculture. Both herbicides can lead to toxicity and changes in the reproductive system. Thus, the objective of the study was to evaluate the impacts of chronic oral and inhalational exposure to 2-4D herbicides and glyphosate on reproductive health in an experimental model, using an environmental spray simulation model. The study was carried out in two experiments: (1) 2,4-D exposure and (2) glyphosate exposure. In each experiment, Wistar rats were divided into 8 experimental groups (n=10/group): 4 inhalation exposure groups (control and 3 concentrations) and 4 oral exposure groups (control and 3 concentrations). The concentrations of herbicides used were: 0 (control group - CG), 20.69 (low concentration group - LCG), 34.63 (medium concentration group - MCG) or 51.66 ppm per day (high concentration group - HCG), The animals (inhalational route) or feed (oral route) were exposed to herbicides daily for 15 minutes, by means of nebulization, for 180 days. After the exposure period, the animals were euthanized and the reproductive organs were collected and weighed. The following parameters were analyzed: organ weight, counts, motility, sperm morphology and vitality, testicular and epididymal histology. At this point, only the results referring to oral exposures will be presented. In the 2,4-D exposure experiment, the percentage of progressively moving sperm and daily sperm production decreased in all groups exposed to the herbicide. Sperm count in the epididymis was reduced in MCG and HCG, and sperm transit time delayed in LCG. There was a negative impact on sperm morphology and plasma membrane integrity in MCG and HCG, respectively. Germ cell desquamation in the testis and epithelial vacuolization in the epididymis were found in the HCG. In the glyphosate exposure experiment, the percentages of progressive and non-progressive moving sperm were reduced and increased, respectively, in HCG. Sperm plasma membrane integrity was not affected by the herbicide. However, there was an increase in head and tail changes in MCG and HCG sperm. Testicular sperm count and testicular and epididymal histology were altered in the three groups exposed to the herbicide. In the testis, seminiferous tubules with structural disorganization and loss of germ cells, exfoliated germ cells in the lumen and intraepithelial vacuolization were found. In the epididymis, specific changes were observed, such as vacuolization of the epithelium, immature germ cells exfoliated in the lumen. Thus, chronic oral exposure to 2,4-D and glyphosate herbicides caused damage to spermatogenesis and sperm quality, with possible repercussions for fertility.