Avaliação do epitélio pulmonar em ratos submetidos ao malation

Abstract

The consumption of pesticides in Brazil has been growing more and more, causing changes in human health and ecosystems. We can identify impacts on the health of both workers and consumers of food contaminated with residues, with product applicators being the most affected. The greatest use of organophosphate pesticides is in agriculture, but they are also used in public health. Malathion is one of the most used organophosphates in Brazil, it has great utility in rural and urban areas. The toxic action of organophosphate compounds is related to the inhibition of numerous enzymes. Inhibition of acetylcholine occurs through the process of phosphorylation of the hydroxyl group of the serine residue of the enzyme. The hydrolysis of the neurotransmitter acetylcholine will be compromised, leading to the accumulation of this neurotransmitter in the synapses of the central and peripheral nervous system, promoting a hyperstimulation of the muscarinic and nicotinic receptors (cholinergic receptors) triggering a variety of signs and symptoms that characterize the “cholinergic syndrome”. The present study aimed to analyze changes in the pulmonary epithelium in rats submitted to the organophosphate insecticide, Malathion, through histopathological analysis of the pulmonary epithelium of rats submitted to Malathion orally. Thirty female Wistar rats were used, with an initial age of 21 days, from the Central Animal Facility of the State University of Londrina – UEL, Protocol CEUA-7109. The animals were randomly distributed into three experimental groups (n = 10). Two groups of animals were treated with Malathion at doses of 10 mg/kg or 50 mg/kg of body weight via gavage. These doses correspond to 0.5% and 2.5%, respectively, of the oral LD50 for rats (oral LD50 = 2000 mg/kg) (US EPA, 200). The other group (control group) received only the vehicle (soybean oil) in equal volume. The results were obtained through the following analyses; goblet cells; bronchiole area, lumen area, muscle layer thickness and inflammation score. We observed an increase in goblet cells in the M50 group, although we did not identify a statistically significant value, the results were presented as an average, with p<0.05. Regarding the area of the bronchiole lumen, there was a reduction in the area in the group that received the highest dose of malathion, but without statistical value. Regarding the bronchiole area, we identified an increase in the area in the M10 group, compared with both the control and the M50 group, with statistical value. Regarding the thickness of the muscle layer, we observed an increase in thickness in the two groups that received malathion, but without statistical value. In the evaluation of the inflammation score, we found an increase in the score in the M50 group, with statistical significance. The results of the present study demonstrated that exposure to malathion causes alterations in lung histology, such as the presence of inflammation of the bronchioles, as evidenced by the increase in the inflammation score in the group that received the highest malathion dose. We observed an increase in goblet cells in the M50 group, although we did not identify a statistically significant value, the results were presented as an average, with p<0.05. Regarding the area of the bronchiole lumen, there was a reduction in the area in the group that received the highest dose of malathion, but without statistical value. Regarding the bronchiole area, we identified an increase in the area in the M10 group, compared with both the control and the M50 group, with statistical value. Regarding the thickness of the muscle layer, we observed an increase in thickness in the two groups that received malathion, but without statistical value. In the evaluation of the inflammation score, we found an increase in the score in the M50 group, with statistical significance. The results of the present study demonstrated that exposure to malathion causes alterations in lung histology, such as the presence of inflammation of the bronchioles, as evidenced by the increase in the inflammation score in the group that received the highest malathion dose. In addition, we also found an increase in goblet cells, an increase in the area of the bronchioles, a reduction in the lumen area and changes in the thickness of the muscle layer, but we did not prove statistically significant values. Thus, it is important to carry out new research in relation to the topic addressed, so that we can obtain more data to implementation of alternatives that are evidently safer, both for the environment and for the population.