Intergenerational thyroid hormone homeostasis imbalance in cerebellum of rats perinatally exposed to glyphosate-based herbicide.

Agrochemicals became a public health concern due to increased human exposure and possible endocrine disruption effects in several organs, including the brain. Thyroid hormones controls neurodevelopment, which turn them sensitive to endocrine disruptors (EDs). In this work, we evaluated the effect of glyphosate-based herbicides (GBH) as an intergenerational endocrine disrupter on thyroid homeostasis in cerebellar cells. Female pregnant Wistar rats were exposed to Roundup Transorb® solution at 5 and 50 mg/kg/day, from gestation day 18 to post-natal day 5 (P5). Cerebellum of male offspring was used to evaluate gene expression. The mRNA levels of thyroid hormone receptors, hormonal conversion enzymes, hormone transporters, as well as, de novo epigenetic regulators were altered, with some of these genes presenting a non-monotonic dose response. Furthermore, metabolomic profile correlation with tested dose demonstrated altered metabolic profile, in agreement with cerebellar gene alterations. Moreover, cerebellar primary cultures exposed to non-toxic GBH concentration presented a decrease level in glial fibrillary acidic protein, a protein regulated by endocrine signals. In conclusion, our results indicate that animals exposed to non-toxic GBH doses during perinatal phase carry intergenerational alterations in key regulators of cellular thyroid hormone homeostasis and epigenetic controllers in adulthood, indicating the possible ED effect of GBH based on epigenetic alterations.

Proteomic Profiles of Thyroid Gland and Gene Expression of the Hypothalamic-Pituitary-Thyroid Axis Are Modulated by Exposure to AgNPs during Prepubertal Rat Stages.

Silver nanoparticles (AgNPs) have potent antimicrobial activity and, for this reason, are incorporated into a variety of products, raising concern about their potential risks and impacts on human health and the environment. The developmental period is highly dependent on thyroid hormones (THs), and puberty is a sensitive period, where changes in the hormonal environment may have permanent effects. We evaluated the hypothalamic-pituitary (HP)-thyroid axis after exposure to low doses of AgNPs using a validated protocol to assess pubertal development and thyroid function in immature male rats. For stimulatory events of the HP-thyroid axis, we observed an increase in the expression of Trh mRNA and serum triiodothyronine. Negative feedback reduced the hypothalamic expression of Dio2 mRNA and increased the expression of Thra1, Thra2, and Thrb2 mRNAs. In the pituitary, there was a reduced expression of Mct-8 mRNA and Dio2 mRNA. For peripheral T3-target tissues, a reduced expression of Mct-8 mRNA was observed in the heart and liver. An increased expression of Dio3 mRNA was observed in the heart and liver, and an increased expression of Thrb2 mRNA was observed in the liver. The quantitative proteomic profile of the thyroid gland indicated a reduction in cytoskeletal proteins (Cap1, Cav1, Lasp1, Marcks, and Tpm4; 1.875 µg AgNP/kg) and a reduction in the profile of chaperones (Hsp90aa1, Hsp90ab1, Hspa8, Hspa9, P4hb) and proteins that participate in the N-glycosylation process (Ddost, Rpn1 and Rpn2) (15 µg AgNP/kg). Exposure to low doses of AgNPs during the window of puberty development affects the regulation of the HP-thyroid axis with further consequences in thyroid gland physiology.

Prepubertal acrylamide exposure causes dose-response decreases in spermatic production and functionality with modulation of genes involved in the spermatogenesis in rats.

The increase in human infertility prevalence due to male reproductive disorders has been associated with extensive endocrine-disrupting chemical (EDC) exposure. Acrylamide (AA) is a compound formed spontaneously during heat processing of some foods that are mainly consumed by children and adolescents. In this study, we evaluated the prepubertal AA exposure effects on male adult reproductive physiology using a prepubertal experimental model to analyze the pubertal development, spermatogenesis hormones levels and genes expression involved in male reproductive function. This study is the first one to use the validated protocol to correlate the AA exposure with puberty development, as well as the AA-induced endocrine disrupting effects on reproductive axis. AA did not affect the age at puberty, the reproductive organ's weight and serum hormonal levels. AA reduces spermatogenesis, induces morphological and functional defects on sperm and alters transcript expression of sexual hormone receptors (Ar and Esr2), the transcript expression of Tnf, Egr2, Rhcg and Lrrc34. These findings suggest that excessive AA consumption may impair their reproductive capacity at adulthood, despite no changes in hormonal profile being observed.

Imbalanced testicular metabolism induced by thyroid disorders: New evidences from quantitative proteome.

Thyroid dysfunctions, such as hypothyroidism and hyperthyroidism, are the second most prevalent endocrinopathies and are associated to reproductive disorders in men. Several genes are differentially modulated by thyroid hormones in testes and imbalances in thyroid hormone levels are also associated to alterations on sperm functionality. Imbalances on antioxidant defense mechanism and stress oxidative have been pointed out as the main factors for the impairments on male reproductive function. To clarify this issue, we investigated the expression and activity of antioxidant enzymes in testis, followed by their proteomic profile in attempt to characterize the mechanisms involved in the alterations induced by hypo- or hyperthyroidism in adult male rats. Hypothyroidism reduced the Gsr transcript expression and the activity of CAT and GSR enzymes, while the hyperthyroidism reduced the Gpx4 var2 transcript expression. Among 1082 identified proteins, 123 and 37 proteins were downregulated by hypothyroidism compared to euthyroid and hyperthyroid condition, respectively, being 36 proteins commonly reduced in both comparisons and one exclusively in hypo-hyperthyroidism comparison. A network containing 29 nodes and 68 edges was obtained in protein-protein interaction analysis and the functional enrichment analysis of differentially expressed proteins revealed significant alterations for several functions in hypo-euthyroid and hypo-hyperthyroid comparisons, such as ATP metabolic process, coenzyme binding, sperm part, peroxiredoxin activity, mitochondrial protein complex, intramolecular oxidoreductase activity, binding of sperm to zona pellucida, glutathione transferase activity, response to testosterone. Thus, there is a correlation between thyroid disorders and impaired antioxidant defense mechanism, resulting in reproductive dysfunctions, as infertility, mainly observed in hypothyroidism.

Effects of diisopentyl phthalate exposure during gestation and lactation on hormone-dependent behaviours and hormone receptor expression in rats.

Phthalates are found in different plastic materials, such as packaging, toys and medical devices. Some of these compounds are endocrine disruptors, comprising substances that are able to induce multiple hormonal disturbances and downstream developmental effects, including the disruption of androgen-dependent differentiation of the male reproductive tract and changes in pathways that regulate hormone-dependent behaviours. In a previous study, metabolites of diisopentyl phthalate (DiPeP), a potent anti-androgenic phthalate, were found in the urine of Brazilian pregnant women. Therefore, the present study aimed to evaluate the effects of DiPeP exposure during critical developmental periods on behaviours controlled by sex hormones in rats. Pregnant Wistar rats were treated with DiPeP (1, 10 or 100 mg kg day-1 ) or canola oil by oral gavage between gestational day 10 and post-natal day (PND) 21. Male offspring were tested in a behavioural battery, including the elevated plus maze task, play behaviour, partner preference and sexual behaviour. After the behavioural tests, the hypothalamus and pituitary of these animals were removed on PND 60-65 and PND 145-160 to quantify gene expression for aromatase, androgen receptor (Ar) and oestrogen receptors α (Esr1) and ß (Esr2). Male rats exposed to 1 and 10 mg kg day-1 DiPeP displayed no preference for the female stimulus rat in the partner preference test and 1 mg kg day-1 DiPeP rats also showed a significant increase in mount and penetration latencies when mated with receptive females. A decrease in pituitary Esr1 expression was observed in all DiPeP treated groups regardless of age. A reduction in hypothalamic Esr1 expression in rats exposed to 10 mg kg day-1 DiPeP was also observed. No significant changes were found with respect to Ar, Esr2 and aromatase expression in the hypothalamus. These results suggest that DiPeP exposure during critical windows of development in rats may induce changes in behaviours related to mating and the sexual motivation of males.