Effects of a Mixture of Pesticides on the Adult Female Reproductive System of Sprague-Dawley, Wistar, and Lewis Rats

Abstract

The Brazilian federal government Agency for Health Surveillance detected pesticide residues in fresh food available for consumers all over the country. The current study investigated the effects of a mixture of some of those pesticides (dichlorvos, dicofol, dieldrin, endosulfan, and permethrin) on the reproductive system of Sprague-Dawley (SD), Wistar (WT), and Lewis (LEW) rats. Female rats from each strain were randomized into three experimental groups and were fed a control diet or diets added with pesticides mixture at their respective no-observed-effect level (NOEL)/no-observed-adverse-effect level (NOAEL) (low dose) (mg/kg/d): dichlorvos (0.23), dicofol (0.5), dieldrin (0.025), endosulfan (0.7), permethrin (5), or lowest-observed-effect level (LOEL)/lowest-effect level (LEL)/ lowest-observed-adverse-effect level (LOAEL) (toxically effective dose) (mg/kg/d): dichlorvos (2.3), dicofol (2.1), dieldrin (0.05), endosulfan (3.8), and permethrin (25) as reported in the literature. Euthanasia was performed between wk 10 and 12, during the estrous stage. Decreased body weights gain (SD and WT) and increased liver weights (SD, WT, and LEW) were observed in each strain fed the pesticides mixture at the higher levels. At that dose level, rat strains also varied in their responses regarding the estrous cycle, hormonal levels, and number of developing ovarian follicles. The studied mixture of pesticides was found to interfere with the female reproductive system when individual pesticides were mixed above a certain level, indicating a threshold exists for each of the strains studied.

Influence of estrous cycle hormonal fluctuations and gonadal hormones on the ventilatory response to hypoxia in female rats

“…According to Hodges et al [22], hyperventilation during hypoxia is similar among different female and male rat strain (Brown Norway, Dahl salt-sensitive, Fawn-hooded hypertensive, Sprague-Dawley). Further, no differences were observed among different rat strain regarding duration of the estrous cycle phases and hormonal variation [34].…”

Larval Exposure to Chlorpyrifos Affects Nutritional Physiology and Induces Genotoxicity in Silkworm Philosamia ricini (Lepidoptera: Saturniidae)

“…Therefore, Chlorpyrifos has been reported as one of the commonly used organophosphate pesticide (Kiely et al, 2004; John and Shaike, 2015). However, this pesticide enters and contaminates the environment either by direct application, spray drifts or crop run off and shows adverse effect on the non-targeted wildlife populations starting from microorganism to higher vertebrates (Watson et al, 2014; Ahmad et al, 2015; Jin et al, 2015; John and Shaike, 2015; Pascotto et al, 2015). …”

In utero and lactational exposure to fipronil in female rats: Pregnancy outcomes and sexual development

“…Estrus cycle monitoring is a basic method of evaluating the reproductive capacity of a female animal, and abnormality in reproductive function is often associated with estrus disruption (Shaikh et al, 1971). It was demonstrated that change in estrus cyclicity and cycle length may be related to stress, light/dark cycle (Everett et al, 1989), presence of males (Mora et al, 1985;Barkley et al, 1993), prolactin and progesterone levels (Van der Schoot and Uilenbroek, 1983;Sánchez-Criado, 1996), and exposure to pesticides (Hayashi et al, 2013;Nishi et al, 2013;Pascotto et al, 2015). In adult life, female offspring exposed to a dose of 0.3 mg/kg fipronil showed changes in the estrus cycle, such as an increase in estrus cycle length and decrease in the number of cycles.…”