Screening for in vivo (anti)estrogenic and (anti)androgenic activities of technical and formulated deltamethrin

Rosuvastatin exposure in female Wistar rats alters uterine contractility and do not show evident (anti)estrogenic effects

Statins are 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase inhibitor drugs that lead to serum-cholesterol-lowering effects. Rosuvastatin, a third-generation statin, has shown better results in reducing cholesterol concentrations when compared to other widely prescribed statins. Recent studies by our group reported that rosuvastatin impairs reproductive function in rats possibly by disrupting the reproductive-endocrine axis. In this study, we evaluated whether rosuvastatin presents estrogenic or antiestrogenic effects, by an in vivo uterotrophic assay in rats, and investigated the direct effect of this drug upon rat uterine tissue contractility both in non-gravid and gravid periods. Rosuvastatin exposure in vivo at doses of 0 (control), 3, and 10 mg/kg/d was not associated with estrogenic or antiestrogenic effects on uterine tissue. However, in vivo (doses of 0, 3, and 10 mg/kg/d) and ex vivo (concentrations of 0, 1, 10, and 100 µg/mL) exposures to this drug were related to alterations in uterine basal contraction pattern. Furthermore, in vivo and ex vivo rosuvastatin exposures potentially modulate the action of uterine contraction inducers carbachol, norepinephrine, and prostaglandin E2. Thus, rosuvastatin can affect uterine physiology not necessarily by an endocrine mechanism related to the estrogen signaling, but possibly by its pleiotropic effects, with indirect tissue and cellular interactions, since in vivo and ex vivo exposures of uterine fragments to rosuvastatin presented different responses in uterine contractile parameters, which require further studies upon the precise mechanism of action of this drug in female reproductive function.

Perinatal exposure to androgen excess and the effects on the rat uterine estradiol responsiveness

Androgen exposure during sexual development induces alterations in steroidal target tissues. The objective of this study was to evaluate the uterine responsiveness to estradiol after perinatal androgenization. Pregnant Wistar rats were exposed to corn oil or testosterone propionate at 0.05, 0.1, or 0.2 mg/kg from gestational day 12 until postnatal day 21. Female offspring was challenged with estradiol (E₂ ) after weaning (0.4 mg/kg) and at adulthood (10 or 100 µg/day), when the pituitary response was also evaluated. At adulthood, control and 0.05 mg/kg groups presented a uterine weight increment when exposed to 100 µg/day of E₂ , 0.1 mg/kg group only responded to 10 µg/day of E₂ , and the 0.2 mg/kg group showed increased uterine weight at both doses. The pituitary weight was similarly increased after estradiol stimulation in all experimental groups. In conclusion, testosterone propionate exposure induced an abnormal stimulation of uterine tissue growth by estrogen stimulus without affecting pituitary response. More studies are needed to clarify whether these alterations are capable of impairing the reproductive capacity of the female tract. © 2015 Wiley Periodicals, Inc. Environ Toxicol 31: 1460-1468, 2016.

Screening for in vivo (anti)estrogenic and (anti)androgenic activities of Tropaeolum majus L. and its effect on uterine contractility

ETHNOPHARMACOLOGICAL RELEVANCE

Tropaeolum majus L. (Tropaeolaceae) is a medicinal herb popularly used in Brazil for treatment of inflammatory and cardiovascular diseases. Despite some published data on its efficacy, there are still few toxicological data describing the safety of this plant. The aim of this study was to evaluate the (anti)estrogenic and (anti)androgenic activity of the hydroethanolic extract obtained from Tropaeolum majus L. (HETM), as well as its possible effects on uterine contractility.

MATERIALS AND METHODS

Three experimental protocols were performed, (a) uterotrophic assay, (b) Hershberger assay and (c) an ex vivo test to investigate the effects of maternal administration of HETM on uterine contractility at the end of pregnancy. In all protocols three doses of the HETM were administered to Wistar rats: 3, 30 and 300mg/kg.

RESULTS

In vivo tests for detection of (anti)androgenic and (anti)estrogenic activities did not show any significant alterations. Similarly, no alterations were observed on uterine contractility induced by oxytocin and arachidonic acid.

CONCLUSIONS

HETM was unable to produce (anti)estrogenic or (anti)androgenic activities in the short-term in vivo screening assays performed. In addition, there was no evidence that HETM can affect uterine contractility following gestational exposure of rats.

Veterinary Pesticides

Veterinary pesticides are used to treat a range of parasitic conditions in companion and farm animals. These products are based on a number of different compounds with different modes of action and different spectra of toxicity. The older agents include the synthetic pyrethroids and organophosphorus compounds, while the newer examples include, for example, representatives of the insect growth promoters, the neonicotinoids, and the oxadiazones. For many of these compounds, toxicity is associated with their pharmacological activity or mode of action. Thus the synthetic pyrethroids and the organophosphorus compounds exert neurotoxic effects. For others, toxicity may be associated with mechanisms that are independent of their mode of action. When used according to the manufacturer's instructions, these products are generally safe and efficacious. However, accidental contamination and misuse can lead to toxicity in operators and treated animals. These compounds are important in the treatment of parasitic disease in animals and their regulation and uses are based on favourable risk-benefit outcomes.

Assessing hormone receptor activities of pyrethroid insecticides and their metabolites in reporter gene assays

Pyrethroid insecticides, the most commonly used insecticides worldwide, are suspected endocrine-disrupting chemicals. But their interactions with hormone receptors are still unclear. The present study intended to evaluate and compare the hormone receptor (estrogen receptor [ER], androgen receptor [AR], and thyroid hormone receptor [TR]) activities of nine pyrethroids (cycloprothrin, cyfluthrin, cyhalothrin, cypermethrin, deltamethrin, etofenprox, fenvalerate, permethrin, and tetramethrin) and their metabolites (3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropne carboxylic acid [DCCA] and 3-phenoxybenzoic acid [3-PBA]) using receptor-mediated luciferase reporter gene assays. Of the 11 compounds tested, four showed very weak ER agonistic activities and six displayed antiestrogenic effects, among which cyhalothrin and DCCA possessed the most potent estrogenic and antiestrogenic activity respectively. Antagonistic effects to AR were found in 7 compounds, with cyfluthrin and deltamethrin exhibiting stronger AR antagonistic capacity. In the TR assay, all of tested chemicals except DCCA showed antagonistic effects. In this study, we provided evidence that a variety of pyrethroids and their metabolites might disrupt the function of multiple nuclear hormone receptors and thus have the potentials to affect the endocrine and the reproductive systems in humans.

Effects of Tribulus terrestris on endocrine sensitive organs in male and female Wistar rats

AIM OF THE STUDY

Investigate the possible effects of Tribulus terrestris (TT) on endocrine sensitive organs in intact and castrated male rats as well as in a post-menopausal rat model using ovariectomized females.

MATERIALS AND METHODS

Three different dose levels of TT (11, 42 and 110 mg/kg/day) were administered to castrated males for 7 days and to intact males and castrated females for 28 days. In addition to TT treatment, all experiments also included a group of rats treated with dehydroepiandrosterone (DHEA). In experiments using castrated males and females we also used testosterone and 17 alpha-ethynylestradiol, respectively, as positive controls for androgenicity and estrogenicity.

RESULTS

Neither DHEA nor TT was able to stimulate androgen sensitive tissues like the prostate and seminal vesicle in both intact and castrated male rats. In addition, administration of TT to intact male rats for 28 days did not change serum testosterone levels as well as did not produce any quantitative change in the fecal excretion of androgenic metabolites. However, a slight increase in the number of homogenization-resistant spermatids was observed in rats treated with 11 mg/kg/day of TT extract. In ovariectomized females, TT did not produce any stimulatory effects in uterine and vaginal epithelia.

CONCLUSIONS

Tribulus terrestris was not able to stimulate endocrine sensitive tissues such as the prostate, seminal vesicle, uterus and vagina in Wistar rats, indicating lack of androgenic and estrogenic activity in vivo. We also showed a positive effect of TT administration on rat sperm production, associated with unchanged levels of circulating androgens.

Morinda citrifolia Linn (Noni): in vivo and in vitro reproductive toxicology

Morinda citrifolia Linn (syn. Noni) is a plant widely used as food and medicine worldwide but there are no toxicological tests about this plant focused on reproduction.

AIM OF THE STUDY

To investigate possible endocrine activity and toxic effect on the reproductive system of Wistar rats by exposure of aqueous extract of the Morinda citrifolia.

MATERIALS AND METHODS

Two experimental protocols in vivo were developed, (a) uterotrophic assay and (b) in utero and lactational assay, and one test in vitro to investigate the effect on the contractility of pregnant uteri isolated from rats (doses of the extract: 7.5, 75 and 750 mg/kg).

RESULTS

The uterotrophic assay indicates presence of in vivo antiestrogenic activity of extract at doses of 7.5 and 750 mg/kg. The in utero and lactation exposure showed that the treatment with extract at the dose of 7.5mg/kg induced a reduction of 50% in parturition index and an increase of 74% in postimplantation losses index. The in vitro test showed that uteri from rats treated with 7.5mg/kg of the extract presented a 50% reduction on contraction induced by arachidonic acid.

CONCLUSION

The exposure of aqueous extract of Morinda citrifolia in Wistar rats induced reproductive toxicity in nonlinear dose-response.

Fenvalerate, a pyrethroid insecticide, adversely affects sperm production and storage in male rats

The aim of this study was to investigate the potential estrogenic activity of fenvalerate by examining reproductive and fertility capabilities in Wistar rats. Adult male animals were treated for 30 d with 20 or 40 mg/kg/d fenvalerate or corn oil (vehicle) by oral gavage. Further, a possible estrogenic activity of fenvalerate (0.4, 1, 4, 8, or 40 mg/kg) was tested after a 3-d treatment of immature female rats using the uterotrophic assay. Exposure to the higher dose of fenvalerate was toxic to testis and epididymis as shown by a decrease in the absolute weights and sperm counts in both organs. Although the sperm counts were reduced, the fertility and sexual behavior were similar in control rats and rats treated with 40 mg/kg pesticide. Fenvalerate did not exert estrogenic activity in vivo at the tested doses. Data suggest that fenvalerate treatment in this study failed to compromise fertility, possibly due to enhanced reproductive capacity in rodents compared to humans.

Chenopodium album seed extract: a potent sperm-immobilizing agent both in vitro and in vivo

PURPOSE

Aqueous decoction of Chenopodium album seeds (CAD) was assessed for its sperm-immobilizing and contraceptive efficacy in laboratory mammals.

METHOD

Spermicidal efficacy was evaluated in vitro by a modified Sander-Cramer test. The mode of spermicidal action was assessed by (a) supravital and double fluoroprobe staining of sperm, (b) hypoosmotic swelling tests and (c) transmission electron microscopy. Contraceptive efficacy was evaluated by intrauterine and vaginal application of CAD in rats and rabbits, respectively, followed by their mating and evaluation of pregnancy outcomes.

RESULTS

The minimum effective concentration of CAD that induced instantaneous immobilization of rat spermatozoa in vitro was 2 mg/mL. The mechanism of CAD action involved disintegration of sperm plasma membrane and dissolution of acrosomal cap causing sperm death. Fertilization of oocytes and establishment of implantation were prevented in the uterine horn that was administered with CAD, while these events occurred unhindered in the untreated contralateral side. In rabbit, intravaginal application of CAD significantly blocked the establishment of pregnancy.

CONCLUSION

CAD possesses appreciable spermicidal potential, which may be explored as an effector constituent of vaginal contraceptive.

Comparison of prostate cancer cell lines for androgen receptor-mediated reporter gene assays

In order to select a better prostate cancer cell model for androgen receptor (AR)-mediated reporter gene assays, we assessed the androgen response characteristics of three cell lines, LNCaP, PC3/AR(+) and 22Rv1, in this study. Both the mRNA and the proteins of AR and glucocorticoid receptor (GR) were expressed in all three cell lines. Among the three cell lines, only in LNCaP cells, DHT concentration-dependently stimulated proliferation. DHT induced the luciferase activity in three cell lines which were transiently transfected with pMMTV-Luc, in a concentration-dependent manner. The maximum induction was 24.0-fold and 13.4-fold in 22Rv1 and in the LNCaP respectively. PC3/AR(+) were more sensitive to respond to DHT at a minimal concentration of 10(-12)M by 14.0-fold induction. The transcriptional activity induced with 10(-8)M DHT was inhibited about 50-75% in the PC3/AR(+) and 22Rv1, and 98% in the LNCaP, by vinclozolin. Dexamethasone concentration-dependently induced the luciferase activity in PC3 and 22Rv1, but not in the LNCaP. However, the response to dexamethasone in 22Rv1 was very weak compared to DHT. The (anti)androgencity of seven pyrethroids was assessed via an AR-mediated luciferase reporter assay. None of them showed the androgenic action in all three cell lines. Permethrin inhibited the DHT induced luciferase activity about 22%, 35.8% and 75.5% in 22Rv1, PC3/AR(+) and LNCaP, respectively. Based on results from in this study and cell line character, 22Rv1 cells seemed to be an appropriate model for the screening of androgenic endocrine disruptors, although it needs further studies with other steroid receptor and thyroid receptor.

Assessment of estrogenic and androgenic activities of tetramethrin in vitro and in vivo assays

Tetramethrin, a synthetic pyrethroid insecticide, is used globally for agriculture, and thus potential environmental exposure to tetramethrin is a concern. Environmental chemicals that are hormonally active (particularly estrogen or androgen) may adversely affect the reproductive and endocrine systems. However, little is known about the estrogenic and androgenic activities of tetramethrin. In this study, uterine CaBP-9k gene expression assay and a uterotrophic assay were conducted for estrogenic activity assessment of tetramethrin, and a Hershberger assay was conducted for androgenic activity. Estrogen receptor (ERalpha and ERbeta) protein levels were also measured in tetramethrin-treated rat uteri. Northern blot analysis showed reduction in uterine CaBP-9k mRNA levels in response to tetramethrin, as well as when rats were given both tetramethrin and 17beta-estradiol (E2). In the uterotrophic assay using 18-d-old female Sprague-Dawley rats, subcutaneous treatment with tetramethrin (5 to 800 mg/kg/day) for 3 d led to a statistically significant decrease in absolute and relative uterine wet weights at all doses tested. Moreover, tetramethrin blocked the effect of E2 on uterine weights. In addition, tetramethrin reduced absolute and relative vaginal wet weights, and also inhibited the increases of vaginal weights produced by E2. Tetramethrin showed no androgenic on antiandrogenic activities in the Hershberger assay. These results suggest that tetramethrin might exert endocrine-disrupting effects on female rats through antiestrogenic action.

Reproductive evaluation of two pesticides combined (deltamethrin and endosulfan) in female rats

Data from in vitro studies suggest that the pesticides deltamethrin (D) and endosulfan (E) exert estrogen-like effects. There is concern that interaction between weakly estrogenic compounds can increase their estrogenic potency. The aim of the present study was to determine estrogenic activity in an animal model and the possible female reproductive adverse effects of these pesticides combined. Wistar rats received daily (po), from day 6 of pregnancy to day 21 of lactation, deltamethrin and endosulfan concomitantly: D: 2.0 mg/kg+E: 1.5 mg/kg, or D: 3.0 mg/kg+E: 2.0 mg/kg, or D: 4.0 mg/kg+E: 3.0mg/kg. Some offspring also were exposed directly after weaning. Maternal and reproductive outcome data were assessed. An uterotrophic assay to screen in vivo estrogenic activity of D+E was also performed. A group of female offspring was analyzed for vaginal opening (VO), first estrus, estrous cycle regularity, and weights of the uterus and ovaries. No signs of maternal toxicity were detected. Results from the uterotrophic assay indicate absence of in vivo estrogenic activity of D+E. No significant variations in reproductive endpoints of females were observed. These results suggest that administration of D+E does not pose a reproductive hazard to female rats exposed during critical periods of development, indicating that the combination does not exert estrogen-like effects in vivo or is not delivered to target organs.

Potential estrogenic and antiandrogenic effects of permethrin in rats

Many environmental chemicals including pesticides have been reported to possess hormonal activities, and thus are classified as endocrine disruptors. Permethrin, a synthetic pyrethroid insecticide, is used worldwide, which provides potential environmental exposure. However, relatively few studies have reported on hormonal activities, particularly estrogenic and androgenic activities of permethrin, and the results of these studies are in some respects contradictory. Therefore, this study investigated the potential estrogenic and androgenic activities of permethrin in vitro and in vivo. We conducted an uterine Calbindin-D9k (CaBP-9k) gene expression assay and an uterotrophic assay for estrogenic activity, and a Hershberger assay for androgenic activity. The CaBP-9k gene, one of the intracellular calcium binding proteins, is estrogen-responsive in the uterus. The rat uterotrophic and Hershberger assays are generally used as in vivo short-term screening assays for detecting the estrogenic and androgenic activities of chemicals, although these assays are still being validated by the Organization for Economic Cooperation and Development (OECD). Northern blot analysis showed the induction of uterine CaBP-9k mRNA level in response to permethrin as well as co-administration of permethrin with E2. In the uterotrophic assay using 18-day-old female rats, subcutaneous treatments with permethrin (10 to 800 mg/kg) for three days increased relative uterine wet weights, and E2-induced uterine weights. These effects were statistically significant at 800 and 200 mg/kg, respectively. Moreover, permethrin-induced uterine weights were inhibited by the co-administration of ICI 182,780, an antiestrogen. In the Hershberger assay, the administration of permethrin orally to testosterone propionate-treated castrated male rats led to statistically significant reductions in androgen-dependent sex accessory tissue (ventral prostate, seminal vesicles, levator ani and bulbocavernosus muscles, Cowper's gland and glans penis) weights at all doses tested (10, 50 and 100 mg/kg). These results suggest that permethrin might have estrogen-like effects on female rats, but antiandrogen-like effects on males.

The combined antiandrogenic effects of five commonly used pesticides

In this study, mixture effects of five dissimilarly acting pesticides were analyzed for antiandrogenic effects in vitro and in vivo. Deltamethrin, methiocarb, prochloraz, simazine, and tribenuron-methyl are all commonly used for agricultural and horticultural purposes. Concentration-response curves for the inhibition of R1881-induced transcriptional activity of the androgen receptor (AR) in vitro of each pesticide alone and in an equimolar mixture were obtained. The IC25 values for deltamethrin, methiocarb, prochloraz, and the mixture were 5.8, 5.8, 3.5, and 7.5 microM, respectively. Simazine and tribenuron-methyl were ineffective. Applying the isobole method resulted in an isobole coefficient of 0.94 at IC25 for the effect of the mixture, indicating additive effects of the compounds. Comparison of observed effects and effects calculated by assuming additivity also strongly indicated additive effects of the pesticides in vitro. In vivo, each of the five pesticides and a mixture of the pesticides were tested for antiandrogenic effects in castrated testosterone-treated Wistar rats. The mixture induced a significant change of weights of the levator ani/bulbocavernosus muscle and adrenal glands. Changes in gene expression in ventral prostates were observed as distinct effects on levels of ornithin decarboxylase (ODC) mRNA and effects on levels of prostate binding protein subunit C3 (PBP C3) mRNA. No pesticide-induced effect on the level of testosterone-repressed prostatic message 2 (TRPM-2) mRNA was observed, whereas flutamide increased TRPM-2 levels. In conclusion, the pesticides were found to act additively in vitro. In vivo, the organ weight changes indicated that the pesticides had an accumulating effect that was not observed for the individual pesticides. Several pesticide-induced gene expression changes were observed, indicating that these are either very sensitive antiandrogenic end-points or that these changes are induced by a pathway not related to AR.

Reproductive evaluation of aqueous crude extract of Achillea millefolium L. (Asteraceae) in Wistar rats

The present study was conducted to evaluate the toxicity of the exposure to the aqueous extract from leaves (AE) of Achillea millefolium L. on reproductive endpoints in Wistar rats. Adult male rats were treated daily with yarrow extract (0.3, 0.6 and 1.2 g/kg/day) during 90 days by oral gavage. Endpoints including reproductive organ weights, sperm and spermatid numbers as well as sperm morphology were evaluated. No clinical signs of toxicity were detected over the treatment period, and body weight gain was similar in all groups. A significant increase in the percentage of abnormal sperm in the group treated with the highest dose of yarrow extract was detected with no other important changes in the other reproductive endpoints studied in the male rats. Furthermore, a possible estrogenic/antiestrogenic activity of the yarrow extract screened after a 3-day treatment of immature female rats which did not show any uterotrophic effects.

Reproductive effects of deltamethrin on male offspring of rats exposed during pregnancy and lactation

The effects of low doses of deltamethrin administered to female rats on the reproductive system of male offspring were examined. The dams (n=10-12/group) were treated daily by oral gavage with 0, 1.0, 2.0, and 4.0 mg deltamethrin/kg from day 1 of pregnancy to day 21 of lactation. Maternal and reproductive outcome data and male sexual development landmarks were assessed. Fertility, sexual behavior, and a large number of reproductive endpoints, such as organ weights, sperm evaluations, testosterone concentration, and testicular histology were examined on adult male offsprings. No signs of maternal toxicity were detected at the dose levels tested. Significantly adverse effects were only seen on testicular and epididymal absolute weights and the diameter of seminiferous tubules in the group treated with the highest dose of deltamethrin (4.0 mg/kg). The results indicate that in utero and lactational exposure to deltamethrin may induce subtle changes in reproductive behavior and physiology of male offspring rats at dose levels that do not cause maternal toxicity.