Histopathological changes in the liver and thyroid of mice (Mus musculus) caused by the acaricides: fipronil and thymol

Abstract

The control of tick Rhipicephalus (Boophilus) microplus, that has the cattle as preferential host, has been performed using products based on different chemical substances. However, the indiscriminate use of these products has caused the selection of resistant populations and damages to the environment, contaminating the soil and water. Tickcides, like fipronil (synthetic chemical) and thymol (natural chemical), are applied on cattle through aspersion, causing the death of the ectoparasites. Nevertheless, the effects of these products on nontarget organisms have not been thoroughly investigated. Thus, this study evaluated the morphology of the liver and thyroid of female Mus musculus mice, divided into 5 treatment groups/5 individuals each, exposed to fipronil (2%) and thymol (2 mg/mL) through aspersion baths. After exposure, the mice were euthanized with anaesthetic overdose and dissected for organ removal. The results showed that both fipronil and thymol caused morphological alterations in the organs: cytoplasmic vacuolation, cell death characteristics in hepatocyte nuclei and structural disorganization of the thyroid gland. Along with body weight measurement, the results suggest that the morphological alterations would be a systemic response of the organism to the toxic action of these products, regardless their origin (synthetic of natural).

Protective Effect of Red Okra (Abelmoschus esculentus (L.) Moench) Pods against Sodium Nitrite-Induced Liver Injury in Mice

“…Also, the inflammation in the liver tissue may be caused by hypoxia. NaNO 2 causes a mismatch between the supply and demand of oxygen, causing a surge in ROS production that mediates inflammation [58,60]. During hypoxiation, HIF-1α is overexpressed and translocated to the nucleus to bind with the HIF-1β and its cofactor p300/CBP.…”

“…e HIF aims to make the cell more glycolytic and produce ATP efficiently, hence producing lactate that enhances inflammation by boosting interleukin-6 and interleukin-23 from macrophage and succinate activates the macrophages [57]. e accumulation of macrophage around the portal area and in the parenchymal hepatocytes is associated with cells' mechanism to eliminate toxic materials to preserve the normal metabolic activities [60].…”

Liver and spleen of hosts of Rhipicephalus linnaei exposed to synthetic (afoxolaner) and natural acaricides (esters from castor oil). A comparative clinical-morphological study

“…Along with the steatosis observed in the liver of rabbits exposed to afoxolaner, the onset of cytoplasmic vacuolation around the hepatocyte nucleus was noted. Previous work by Cunha et al (2017) and Roma et al (2012) showed the occurrence of cytoplasmic vacuolation, including around the nucleus in the liver of mice ( Mus musculus ) due to the exposure to synthetic acaricides fipronil, thymol, and permethrin, which could suggest a strategy of hepatocyte preservation in response to the presence of the toxic element in the tissue. In other words, this vacuolation would be removing damaged organelles or even certain regions of the cytoplasm that were altered by the presence of the toxic element, sheltering them in vacuoles that would later be digested and/or eliminated, thus preserving the content that was still intact in the cytoplasm.…”

“…However, despite the efficiency of esters as acaricides, little is known about their effects on non-target organisms. Many studies, including those by Cunha et al (2017) , Sodelli et al (2022) , and Vieira et al (2006) , highlighted that these compounds can be toxic to both hosts and non-target organisms, despite their potency as acaricides. Synthetic chemical-based acaricides, such as afoxolaner, have gained prominence in the veterinary market.…”

“…Histochemistry to detect polysaccharides in the liver of rabbits exposed to afoxolaner showed hepatocytes with cytoplasmic areas containing polysaccharide granulation aggregates distributed over almost the entire extent of the cells, data different from those found in the CG, which presented preserved liver tissue, with homogeneous cytoplasm. According to some authors ( Cunha et al, 2017 ; Junqueira & Carneiro, 2017 ), the increase and accumulation of polysaccharides in the cytoplasm of hepatocytes exposed to toxic products could be the result of processes involved with the elimination of metabolites, in this case, the afoxolaner.…”