Disruption of the developmental programming of the gonad of the broad snouted caiman (Caiman latirostris) after in ovo exposure to atrazine.

Environmental exposure to agrochemicals during early stages of development can induce subtle alterations that could permanently affect normal physiology. Previously, we reported that in ovo exposure to atrazine (ATZ) disrupts testicular histoarchitecture in postnatal caimans (Caiman latirostris). To assess whether such alterations are the result of disruption of gonadal developmental programming, this study aimed to evaluate the expression of histofunctional biomarkers (VASA, ER, PR, PCNA, and aromatase) and genes involved in gonadal development and differentiation (amh, sox-9, sf-1 and cyp19-a1) in the gonads of male and female caiman embryos and to assess the effect of ATZ exposure on these biomarkers and genes in the gonads of male embryos. Our results suggest that amh, aromatase and sox-9 play a role in sex determination and gonadal differentiation. In male caiman embryos, ATZ exposure increased aromatase expression and altered the temporal expression pattern of amh and sox-9 evidencing an ATZ-induced disruption of gonadal developmental programming. Since the effects of ATZ are consistent across all vertebrate classes, the ATZ-mediated disruptive effects here observed could be present in other vertebrate species.

Dietary withdrawal of phytoestrogens resulted in higher gene expression of 3-beta-HSD and ARO but lower 5-alpha-R-1 in male rats.

Removing dietary phytoestrogens causes obesity and diabetes in adult male rats. Based on the facts that hypothalamic food intake control is disrupted in phytoestrogen-deprived animals and that several steroids affect food intake, we hypothesized that phytoestrogen withdrawal alters the expression of hypothalamic steroidogenic enzymes. Male Wistar rats fed with a high-phytoestrogen diet from conception to adulthood were subjected to phytoestrogen withdrawal by feeding them a low-phytoestrogen diet or a high-phytoestrogen, high-fat diet. Withdrawal of dietary phytoestrogens increased 3ß-hydroxysteroid dehydrogenase and P450 aromatase gene expression and decreased those of 5α-reductase-1. This is a direct effect of the lack of dietary phytoestrogens and not a consequence of obesity, as it was not observed in high-fat-fed rats. Phytoestrogen withdrawal and high-fat diet intake reduced hypothalamic expression of estrogen receptor (ER)α correlated with low levels of ERα-O, ERα-OS, and ERα-OT transcripts. Variations in gene expression of steroidogenic enzymes may affect the content of neurosteroids. As neurosteroids are related to food intake control, the changes observed may be a novel mechanism in the regulation of energy balance in obese phytoestrogen-deprived animals. In rats, steroidogenesis and ER signaling appear to be altered by phytoestrogen withdrawal in the rat. The ubiquity of phytoestrogens in the diet and changing intakes or withdrawal suggest that aspects of human health could be affected based on the rat and warrant further research.

Dietary whey reduces energy intake and alters hypothalamic gene expression in obese phyto-oestrogen-deprived male rats.

Removing dietary phyto-oestrogens in adult male rats causes obesity and diabetes. As whey proteins have been reported to reduce food intake and improve glucose homoeostasis, we investigated whether they could attenuate susceptibility to obesity and diabetes due to phyto-oestrogen deprivation. To this end, thirty male Wistar rats were fed a high-phyto-oestrogen (HP) or a phyto-oestrogen-free (PF) diet for 10 weeks; six rats from each group were killed. The remaining HP animals (six animals) continued receiving the HP diet for 6 weeks. The remaining PF rats (twelve rats) were divided in two groups: one was given the PF diet and the other a variation of the PF diet plus whey protein (PF-W). Body weight, food intake and adipose tissue weights were recorded. Hypothalamic mRNA expressions of orexigenic (neuropeptide Y, agouti-related protein (AgRP)) and anorexigenic (pro-opiomelanocortin (POMC), cocaine-amphetamine-related transcript (CART)) neuropeptides were quantified by real-time PCR. Serum glucose, insulin and total thyroxine (T4), thyroid-stimulating hormone, testosterone and oestradiol were assessed. After 10 weeks of PF diet, increased body weight, adiposity and energy intake, with up-regulation of AgRP and down-regulation of POMC', were observed. Longer treatment exacerbated these results, increased total T4 levels, reduced oestradiol levels and impaired glucose homoeostasis. PF-W reduced energy intake and increased POMC expression; however, body weight and adiposity remained unchanged. PF-W could not prevent the hormonal changes or the high circulating glucose levels induced by phyto-oestrogen deprivation, but reduced fasting insulin. These data demonstrate that, although 6 weeks of whey administration could not prevent obesity in phyto-oestrogen-deprived rats, the reduction in energy intake and circulating insulin could be beneficial with longer treatments.

Pregnancy and lactation differentially modify the transcriptional regulation of steroidogenic enzymes through DNA methylation mechanisms in the hippocampus of aged rats.

In the present study, we examined the mRNA expression and DNA methylation state of steroidogenic enzymes in the hippocampus of young adult (90-days-old) and middle-aged (450-days-old) nulliparous rats, and middle-aged multiparous rats subjected to three pregnancies with and without lactation. Aging decreased the mRNA levels of steroidogenic-related genes, while pregnancy and lactation significantly reduced the effect of aging, maintaining high expression levels of cytochrome P450 side-chain cleavage (P450scc), steroid 5α-reductase-1 (5αR-1), cytochrome P450arom (P450arom) and aldosterone synthase (P450(11ß)-2). In addition, pregnancy and lactation diminished the methylation state of the 5αR-1 promoter and increased the transcription of brain-derived neurotrophic factor, synaptophysin and spinophilin. Pregnancy without lactation increased P450scc and 5αR-1 gene expression and decreased the methylation of their promoters. We concluded that the age-related decrease in the mRNA expression of steroidogenic enzymes is differentially attenuated by pregnancy and lactation in the rat hippocampus and that differential methylation mechanisms could be involved.