Endocrine Disruptors: Focus on the Adrenal Cortex

Effects of Endocrine-Disrupting Chemicals on Adrenal Function

The adrenal glands play crucial roles in regulating metabolism, blood pressure, immune system function, and response to stress through the secretion of hormones. Despite their critical functions, the adrenal glands are often overlooked in studies on the effects of potential toxicants. Research across human, animal, and in vitro studies has identified more than 60 compounds that can induce adrenocortical toxicity. These compounds, known as endocrine-disrupting chemicals (EDCs), are natural or synthetic substances that interfere with the endocrine system. This review aims to provide an overview of the effects of 4 major families of EDCs-flame retardants, bisphenols, phthalates, and microplastics-on the function of the adrenal glands. The PubMed database was searched for studies reporting the effects of the chemicals in these 4 families on the adrenal glands. There is clear evidence that the morphology and function of the adrenal gland are affected, particularly through disrupting the steroidogenic pathway. Additionally, some EDCs have been shown to exert transgenerational effects, raising further concerns about their long-term effect. However, most EDCs have not been thoroughly evaluated for their effects on the function of the adrenal glands, especially in human studies. Thus, developing regulatory testing guideline to include the adrenal glands in the screening of EDCs is urgently needed.

Community-based insights into the connection between endocrine-disrupting chemicals and depressive symptoms

Background

The rising prevalence of depressive disorders has sparked concerns regarding environmental risk factors, particularly exposure to endocrine-disrupting chemicals (EDCs). However, the link between EDC exposure and depressive symptoms remains largely unexplored.

Methods

The Chang Gung Community Medicine Research Center carried out a cross-sectional study across four regions in northeastern Taiwan. Out of 887 participants, 120 subjects were chosen according to their EDC exposure scores. These participants underwent urinary EDC analysis and were evaluated for depressive symptoms through the standardized Hospital Anxiety and Depression Scale - Depression subscale (HADS-D) questionnaire.

Results

Participants with HADS-D scores ≥ 8 exhibited significantly higher EDC exposure score compared to those with lower scores. The correlation analyses identified a notible positive association between urinary monobenzyl phthalate (MBzP) levels and HADS-D scores (r = 0.244, p = 0.007). Multiple regression analysis revealed that MBzP was independently linked to increased HADS-D scores in a positive manner (β ± SE: 0.139 ± 0.050, p = 0.006). Multivariable logistic regression indicated that higher MBzP (OR: 1.150, 95 % CI: 1.036-1.278, p = 0.009) and methylparaben (MP) levels (OR: 1.008, 95 % CI: 1.003-1.013, p < 0.001) showed a significant correlation with the likelihood of HADS-D scores ≥ 8. Receiver operating characteristic curve analysis demonstrated that elevated levels of MBzP, MP and the EDCs exposure score were associated with a greater likelihood of depressive symptoms.

Conclusion

Exposure to EDCs, particularly MBzP and MP, could be associated with a heightened risk of depressive symptoms.

Folliculogenesis and steroidogenesis alterations after chronic exposure to a human-relevant mixture of environmental toxicants spare the ovarian reserve in the rabbit model

BACKGROUND

Industrial progress has led to the omnipresence of chemicals in the environment of the general population, including reproductive-aged and pregnant women. The reproductive function of females is a well-known target of endocrine-disrupting chemicals. This function holds biological processes that are decisive for the fertility of women themselves and for the health of future generations. However, insufficient research has evaluated the risk of combined mixtures on this function. This study aimed to assess the direct impacts of a realistic exposure to eight combined environmental toxicants on the critical process of folliculogenesis.

METHODS

Female rabbits were exposed daily and orally to either a mixture of eight environmental toxicants (F group) or the solvent mixture (NE group, control) from 2 to 19 weeks of age. The doses were computed from previous toxicokinetic data to reproduce steady-state serum concentrations in rabbits in the range of those encountered in pregnant women. Ovarian function was evaluated through macroscopic and histological analysis of the ovaries, serum hormonal assays and analysis of the expression of steroidogenic enzymes. Cellular dynamics in the ovary were further investigated with Ki67 staining and TUNEL assays.

RESULTS

F rabbits grew similarly as NE rabbits but exhibited higher total and high-density lipoprotein (HDL) cholesterol levels in adulthood. They also presented a significantly elevated serum testosterone concentrations, while estradiol, progesterone, AMH and DHEA levels remained unaffected. The measurement of gonadotropins, androstenedione, pregnenolone and estrone levels yielded values below the limit of quantification. Among the 7 steroidogenic enzymes tested, an isolated higher expression of Cyp19a1 was measured in F rabbits ovaries. Those ovaries presented a significantly greater density/number of antral and atretic follicles and larger antral follicles without any changes in cellular proliferation or DNA fragmentation. No difference was found regarding the count of other follicle stages notably the primordial stage, the corpora lutea or AMH serum levels.

CONCLUSION

Folliculogenesis and steroidogenesis seem to be subtly altered by exposure to a human-like mixture of environmental toxicants. The antral follicle growth appears promoted by the mixture of chemicals both in their number and size, potentially explaining the increase in atretic antral follicles. Reassuringly, the ovarian reserve estimated through primordial follicles number/density and AMH is spared from any alteration. The consequences of these changes on fertility and progeny health have yet to be investigated.

Is membrane androgen and estrogen receptor signaling imperative in the governing function of the adrenal cortex in the Eurasian beaver (Castor fiber L.)?

There is a need to fully know the physiology of Eurasian beaver due to its essential role in environmental homeostasis. However, a "human factor" impacts this, including stress conditions and environmental pollution. Adrenal glands protect these all. The regulation of endocrine processes by nonclassical androgen and estrogen signaling, the first and fastest control, is still a matter of research. The specific analyses performed here in mature female and male beaver adrenals contained: anatomical and histological examinations, expression and localization of membrane androgen receptor (zinc transporter, Zinc- and Iron-like protein 9; ZIP9) and membrane estrogen receptor coupled with G protein (GPER), and measurement of zinc (Zn2+) and copper (Ca2+) ion levels and corticosterone levels. We revealed normal anatomical localization, size, and tissue histology in female and male beavers, respectively. Equally, ZIP9 and GPER were localized in the membrane of all adrenal cortex cells. The protein expression of these receptors was higher (p < 0.001) in male than female adrenal cortex cells. Similarly, Zn2+ and Ca2+ ion levels were higher (p < 0.05, p < 0.01) in male than female adrenal cortex. The increased corticosterone levels (p < 0.001) were detected in the adrenal cortex of females when compared to males. The present study is the first to report the presence of nonclassical androgen and estrogen signaling and its possible regulatory function in the adrenal cortex of Eurasian beavers. We assume that this first-activated and fast-transmitted regulation can be important in the context of the effect of environmental physical and chemical stressors especially on adrenal cortex cells. The beaver adrenals may constitute an additional supplementary model for searching for universal mechanisms of adrenal cortex physiology and diseases.