Endocrine Abstracts

JOINT2142

Phthalates, widely used as plasticizers, are well-documented endocrine disruptors associated with adverse effects on reproductive, developmental, and cardiovascular health. Despite being increasingly replaced by substitutes like adipates, terephthalates, and cyclohexane derivatives, these substitutes are produced in large quantities and frequently detected in human samples. While they exhibit lower migration rates from primary applications such as food packaging and medical devices, the effects of long-term exposure on endocrine systems - specifically on adrenal steroidogenesis - remain poorly understood. To evaluate the influence of three established phthalates, adrenal NCI-H295R cells were treated with diethylhexylphthalate (DEHP), diisobutylphthalate (DiBP), and diisononylphthalate DiNP), three non-phthalate alternatives, namely diethylhexyladipate (DEHA), diethylhexylterephthalate (DEHT), and 1, 2-cyclohexane-dicarboxylic acid diisononyl-ester (DINCH), alongside an equimolar mixture of all six substances combined, for 72 hours in triplicate. Cell viability and the secretion of 15 steroids were assessed via LC-MS/MS. While concentrations >100µM were cytotoxic, lower doses of DEHP, DiNP, DEHT, DINCH and the mixture mainly stimulated the mineralocorticoid pathway. Aldosterone levels rose by 2. 30±0. 55-, 2. 76±1. 08-, and 2. 51±1. 49-fold at 10µM of DINCH, DiNP and mixture respectively. Its precursor corticosterone increased by 2. 68±1. 31-, and 2. 79±1. 46-fold at 1µM of mixture and DEHP. Also elevated cortisol levels were detected, e. g. 2. 00±0. 84- or 2. 15±0. 87-fold at 10µM of DINCH and mixture, accompanied by reduced cortisone levels. Notably, 21-deoxycortisol was strongly elevated (e. g. 2. 72±0. 99-fold at 1µM DiNP). While androgens were mildly affected, estradiol was increased. Further, DEHA and DiBP treatment resulted in less altered steroid levels. However, previously described inhibition of androgen levels by phthalates, were not detected following treatment with substitutes (DEHA, DEHT, DINCH). Importantly, all substances induced significant disruption of adrenal steroidogenesis when combined, indicating additive effects of phthalates and non-phthalate substitutes. The observed dysregulation of mineralocorticoids may affect blood pressure and fluid homeostasis. This aligns with evidence linking phthalate exposure to hypertensive phenotypes, particularly in highly exposed neonatal intensive care unit patients. Interestingly, most components are known for altering the renin-angiotensin-aldosterone-system. Alteration of adrenal steroidogenesis could therefore provide a mechanistic explanation for phthalate- or substitute-induced hypertension. Moreover, chronic activation of the hypothalamic-pituitary-adrenal, potentially associated with phthalate exposure, may influence adrenal glucocorticoid synthesis. Although this remains speculative in the context of the current findings, it aligns with previous research highlighting the vulnerability of mineralo- and glucocorticoid synthesis both In vitro and epidemiological studies, to phthalates and their emerging alternatives. This highlights the need for further research on their potential as risk factors for cardiovascular and endocrine health.