Effects of nonylphenol on aldosterone release from rat zona glomerulosa cells

Effects of Nonylphenol on the Secretion of Catecholamines and Adrenocortical Hormones from Short-Term Incubated Rat Adrenal Glands

Previously, we showed that a chronic-low-dose nonylphenol (NP) exposure resulted in histological changes with sexually dimorphic pattern in rat adrenal glands. We hypothesized that such structural changes are closely related to the hormonal secretory patterns. To test this hypothesis, we developed the short-term adrenal incubation method, and measured the levels of catecholamines and cortical steroids using the high-performance liquid chromatography with electrochemical detection (HPLC-ECD) and specific enzyme-linked immunosorbent assay, respectively. The norepinephrine (NE) levels in media from NP-treated female adrenal, except 100 pM NP, were significantly increased [control (CTL) vs 1 nM NP, p<0.001; vs 10 nM NP, p<0.05; vs 100 nM NP, p<0.001; vs 1 μM NP, p<0.01]. The NE secretion from male adrenal was higher when treated with 100 nM and 1 μM NP (CTL vs 100 nM NP, p<0.05; vs 1 μM NP, p<0.05, respectively). The aldosterone level in the female adrenal media treated with 100 pM NP was significantly decreased, on the other hand, that of media treated with 10 nM NP was significantly increased (CTL vs 100 pM NP, p<0.05; vs 10 nM NP, p<0.01). In male adrenal media, the aldosterone levels of 10 nM, 100 nM and 1 μM NP-treated media were significantly declined (CTL vs 10 nM NP, p<0.001; vs 100 nM NP, p<0.001; vs 1 μM NP, p<0.001). These results showed the NP treatment altered secretory pattern of aldosterone from adrenals of both sexes, showing sexual dimorphism. It may be helpful for understanding possible adrenal pathophysiology, and endocrine disrupting chemicals-related sexually dimorphic phenomena in adrenals.

Effect of Nonylphenol on the Structure of Adrenal Cortex in F1 Generation Rats

Previous studies, including our own, indicate that distinct morphological changes in rodent adrenal cortex could be induced by exposure of endocrine disrupting chemicals (EDC). In the present study, we conducted histological analyses of adrenocortical substructure using a nonylphenol-treated F1 rat model. The adrenal weight of NP-5000 group was significantly declined in female rats (p<0.001), while the adrenal weights of NP-treated groups were not significantly changed in male rats. The thickness of zona glomerulosa layers of female rats in NP-5000 group was significantly declined (p<0.001) but zona fasciculata layers were not changed. The zona reticularis layers of NP-treated group were significantly thinner than those of control group (NP-50, p<0.05; NP-5000, p<0.01). In male adrenal glands, there was no significant change of zona glomerulosa layers in NP-treated groups while the thickness of zona fasciculata in NP-5000 group was significantly decreased (p<0.01). Like female rats, the thickness of zona reticularis in NP-treated groups was significantly decreased (NP-50, p<0.001; NP-5000, p<0.05). Present study demonstrated that the adrenal histology could be altered by low-dose NP exposure in F1 rats, and the effect might be sexually dimorphic. Further study will be helpful for understanding possible adrenal pathophysiology induced by EDC exposure, and EDC-related sexually dimorphic phenomena in rodent adrenals.

Investigation of combined effects of propyl paraben and methyl paraben on the hypothalamic-pituitary-adrenal axis in male rats

The aim of this study was to investigate the endocrine-disrupting effects of methyl paraben (MeP) and propyl paraben (PrP) mixture on the hypothalamic-pituitary-adrenal axis (HPA). In this study, six experimental groups were designated. These groups included three control groups (control, corn oil control, and positive control (50 mg/kg/day BPA)) and three dose groups (10, 100, and 500 mg/kg/day MeP+PrP). MeP with PrP were mixed in a 1:1 ratio and administered to the 42-day-old male rats by oral gavage for 30 days. At the end of the experiment, adrenocorticotropic hormone (ACTH), corticosterone and aldosterone hormones were analyzed in serum. Effects of MeP+PrP on the adrenal glands were investigated by immunohistochemical staining of 11ß hydroxylase (CYP11B1) and aldosterone synthase (CYP11B2) enzymes involved in the synthesis steps of corticosterone and aldosterone. Also, pituitary and adrenal glands were examined histopathologically. In the histopathological findings, cortical nodule, congestion, and edema were found in the tissues. In the pituitary gland, cytokeratin rings were detected in all MeP+PrP dose groups, supporting the increase of corticosterone and ACTH. Serum corticosterone, aldosterone, and ACTH hormone levels were increased in the 100 mg/kg/day MeP+PrP and BPA groups. Results obtained from immunohistochemical staining showed that increased staining parallelled increased corticosterone and aldosterone hormone levels. In summary, the results showed that exposure to the MeP+PrP mixture caused a significant increase in ACTH and corticosterone. Also, the MeP+PrP mixture caused a significant increase of CYP11B1 and CYP11B2. MeP+PrP exposure disrupts the normal HPA axis.

Interactive effects of nonylphenol and bisphenol A exposure with oxidative stress on fetal reproductive indices

Nonylphenol (NP) and/or bisphenol A (BPA) may have reproductive effects. Although the mechanisms of action remain unclear, steroid hormones biosynthesis, hypothalamus pituitary adrenal axis activity, oxidative stress, and crosstalk interaction of NP and BPA mixture and its pathways may play a contributory role. This cross-sectional study examined whether the interactive effects of NP/BPA and oxidative stress biomarkers played a role in reproductive indices (penis length and anogenital distance (AGD)) in 244 mother-fetus pairs. Four biomarkers of oxidative stress, (8-hydroxy-2'-deoxyguanosine (8-OHdG), 8-nitroguanine (8-NO₂Gua), 8-iso-prostaglandin F_2α (8-isoPF_2α), and 4-hydroxy-2-nonenal-mercapturic acid (HNE-MA)) were simultaneously analyzed using the high-performance liquid chromatography-electrospray ionization tandem mass spectrometry method. No significant associations were found between reproductive indices and NP/BPA or oxidative stress biomarkers. Maternal exposure to a mixture of NP and BPA may enhance 8-OHdG. Interactive effects were found in the high 8-isoPF_2α group, and prenatal NP exposure was inversely associated with penis length (β = -3.68 mm; p = 0.01). Similar results were noted among boys who were born to mothers in the high 8-isoPF_2α group, in which BPA was inversely associated with penis length (β = -4.43 mm; p = 0.005). Our findings suggest important implications for prenatal exposure to oxidative stress, as evidenced by the 8-isoPF2α level. Thus, NP and BPA may interact to shape fetal reproductive tract development, particularly in boys. The interactive effects of NP/BPA, oxidative stress, and reproductive indices should be considered.

Measurement of endocrine disrupting and asthma-associated chemicals in hair products used by Black women

BACKGROUND

Personal care products are a source of exposure to endocrine disrupting and asthma-associated chemicals. Because use of hair products differs by race/ethnicity, these products may contribute to exposure and disease disparities.

OBJECTIVE

This preliminary study investigates the endocrine disrupting and asthma-associated chemical content of hair products used by U.S. Black women.

METHODS

We used gas chromatography/mass spectrometry (GC/MS) to test 18 hair products in 6 categories used by Black women: hot oil treatment, anti-frizz/polish, leave-in conditioner, root stimulator, hair lotion, and relaxer. We tested for 66 chemicals belonging to 10 chemical classes: ultraviolet (UV) filters, cyclosiloxanes, glycol ethers, fragrances, alkylphenols, ethanolamines, antimicrobials, bisphenol A, phthalates, and parabens.

RESULTS

The hair products tested contained 45 endocrine disrupting or asthma-associated chemicals, including every targeted chemical class. We found cyclosiloxanes, parabens, and the fragrance marker diethyl phthalate (DEP) at the highest levels, and DEP most frequently. Root stimulators, hair lotions, and relaxers frequently contained nonylphenols, parabens, and fragrances; anti-frizz products contained cyclosiloxanes. Hair relaxers for children contained five chemicals regulated by California's Proposition 65 or prohibited by EU cosmetics regulation. Targeted chemicals were generally not listed on the product label.

CONCLUSIONS

Hair products used by Black women and children contained multiple chemicals associated with endocrine disruption and asthma. The prevalence of parabens and DEP is consistent with higher levels of these compounds in biomonitoring samples from Black women compared with White women. These results indicate the need for more information about the contribution of consumer products to exposure disparities. A precautionary approach would reduce the use of endocrine disrupting chemicals in personal care products and improve labeling so women can select products consistent with their values.

An inhibitor of 11-β hydroxysteroid dehydrogenase type 1 (PF915275) alleviates nonylphenol-induced hyperadrenalism and adiposity in rat and human cells

Background

Nonylphenol (NP) is an environmental endocrine-disrupting chemical (EDC) detected in human cord blood and milk. NP exposure in developmental periods results in hyperadrenalism and increasing 11β-hydroxysteroid dehydrogenase I (11β-HSD1) activity in an adult rat model. Alleviating 11β-HSD1 activity is therefore a logical and common way to treat hyperadrenalism. PF915275 (PF; 4′-cyano-biphenyl-4-sulfonic acid (6-amino-pyridin-2-yl)-amide) is a selective inhibitor for 11β-HSD1. This study aimed to determine whether PF915275 could alleviate the hyperadrenalism induced by NP. In addition to a rat model, the effects of NP and PF915275 were measured in human preadipocytes.

Methods

For the in vivo rat model, female adult rats exposed to NP during the developmental period were divided into two treatment groups, with one receiving oral DMSO solution and the other receiving PF915275 once per day for 4 weeks. After the final treatment, the rats from each group were sacrificed for analysis. For the in vitro human model, human preadipocytes received 2 regimens of NP treatment. One treatment regimen occurred before differentiation (to mimic the sensitive developmental period; P exposure), and the other included continuous exposure from preadipocytes to fully differentiated adipocytes (to mimic the growing and adult periods, respectively; C exposure). Protein and RNA were extracted from rat tissues and the preadipocytes for western blot and real-time PCR analysis.

Results

In the rat model, PF915275 alleviated NP-induced effects by interfering with adipogenesis pathways, including enhancing PPARα expression, decreasing PPARγ expression, and reducing both 11β-HSD1 protein and mRNA expression levels. Additionally, PF915275 reduced the effects of the adrenal corticoid synthesis pathway by reducing StAR expression and 11β-hydroxylase and aldosterone synthase activities. With short-term exposure, NP enhanced PPARγ and FASN mRNA expression levels and reduced PPARα expression, whereas PF915275 alleviated these effects. With C exposure, the NP-induced accumulation of intracellular lipids was reduced by PF915275 treatment, which was mediated by decreased PPARγ mRNA and protein expression levels and increased PPARα protein expression.

Conclusions

The effects of NP and PF915275 treatment in both rat and human cell models are similar. Rats may be an appropriate model to study the effects of NP in humans, especially during the developmental period.

Nonylphenol-induced hyperadrenalism can be reversed/alleviated by inhibiting of 11-β hydroxysteroid dehydrogenase type 1

We previously observed that nonylphenol (NP) exposure during development resulted in increases in body weight and hyperadrenalism in adult male offspring. The mechanism of hyperadrenalism includes the primary activation of the adrenal gland and the conversion of inactive glucocorticoids to active glucocorticoids by 11β-HSD1. The inhibition of 11β-HSD1 is investigated as a new therapeutic approach. This study examined the effect of PF915275 (a selective 11β-HSD1 inhibitor) on hyperadrenalism and adipogenesis in male rats exposed to NP during development. The results showed that treatment with the 11β-HSD1 inhibitor PF915275 reversed/alleviated NP-induced hyperadrenalism via the following mechanisms: (1) decreasing serum corticosterone, 11β-hydroxylase, and aldosterone synthase levels; (2) significantly increasing PPARα protein and mRNA expression. In adipose tissue, NP significantly increased PPARγ mRNA expression, whereas PF915275 significantly decreased the level of mRNA expression; and (3) the expression of key regulators/enzymes in the adipogenesis metabolic pathway was also modulated.

In utero and neonate exposure to nonylphenol develops hyperadrenalism and metabolic syndrome later in life. I. First generation rats (F(1))

Nonylphenol (NP) is an endocrine disruptor (ENDR). It is a chemical associated with the production and degradation of nonylphenol ethoxylates (NPE). NPE is widely used as nonionic surfactants. Previously, we observed that NP increased the production of corticosterone and aldosterone from zona fasciculata-reticularis, and zona glomerulosa cells, respectively. By the "fetal origins adult diseases" (Barker hypothesis), we examined the possible impact of NP exposure during developmental (in utero and neonatal) period with focus on disturbed adrenal function and related hyperadrenal syndrome, i.e. Cushings syndrome/metabolic syndrome. In this study, female rats drink NP water during pregnancy and lactation conferred F(1) generation: (1) increase the corticosterone, aldosterone concentration in plasma; (2) increase 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) activity in liver and adipose tissue; (3) increase aldosterone synthase activity in adrenal for adult offspring. Furthermore, it can increase body weight, adrenocorticotropin (ACTH) concentration in plasma, 11β-HSD1 protein expression in liver, steroidogenic acute regulatory (StAR) protein expression and 11β-hydroxylase activity in adrenal for male adult offspring. In summary, NP exposure during developmental period bestowed F(1) generation with hyperadrenalism and its consequence of metabolic syndrome.