In utero exposure to the endocrine disruptor di-(2-ethylhexyl) phthalate promotes local adipose and systemic inflammation in adult male offspring

Background:

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer used to increase the flexibility of polyvinyl chloride. DEHP and its active metabolite mono-(2-ethylhexyl) phthalate are detected in many biological fluids during fetal and postnatal life. In rodent models, in utero DEHP exposure has been shown to alter sexual organ development, decrease testosterone and aldosterone production, increase body and epididymal adipose tissue weight, and raise serum lipids and glucose levels in male offspring.

Objectives:

The objective of this study is to characterize the effects of in utero DEHP exposure on adipose tissue development and function in male offspring.

Methods:

Sprague–Dawley pregnant dams were gavaged 1, 20, 50 or 300 mg DEHP per kg per day from gestational day 14 until birth.

Results:

Global gene expression analyses of postnatal day 60 male offspring that were exposed in utero to 300 mg DEHP per kg per day revealed increased expression of immune response and inflammation markers, and increased expression of differentiation pathway genes in the epididymal whole-adipose tissue and isolated stromal vascular fraction. C-reactive protein and tumor necrosis factor (TNF) serum levels were increased in the 300 mg DEHP in utero-exposed offspring. TNF levels in adipose tissue homogenates were increased in the 50 and 300 mg DEHP in utero-exposed offspring. Immunofluorescence studies revealed focal macrophage infiltration in whole-adipose tissue confirmed by increased CD163 tissue content.

Conclusions:

In utero DEHP exposure promotes local adipose tissue inflammation and chronic low-grade systemic inflammation. Moreover, evidence is presented, suggesting that DEHP increases the differentiation capacity of the pre-adipocytes of male offspring without affecting total body weight.

In utero exposure to the endocrine disruptor di-(2-ethylhexyl) phthalate induces long-term changes in gene expression in the adult male adrenal gland

The plasticizer di-(2-ethylhexyl) phthalate (DEHP) is used to add flexibility to polyvinylchloride polymers and as a component of numerous consumer and medical products. DEHP and its metabolites have been detected in amniotic fluid and umbilical cord blood, suggesting fetal exposure. In the present study, we used an in utero exposure model in which pregnant rat dams were exposed to 1- to 300-mg DEHP/kg·d from gestational day 14 until birth. We previously reported that this window of exposure to environmentally relevant doses of DEHP resulted in reduced levels of serum testosterone and aldosterone in adult male offspring and that the effects on aldosterone were sustained in elderly rats and resulted in decreased blood pressure. Here, we characterized the long-term effects of in utero DEHP exposure by performing global gene expression analysis of prepubertal (postnatal d 21) and adult (postnatal d 60) adrenal glands. We found that the peroxisome proliferator-activated receptor and lipid metabolism pathways were affected by DEHP exposure. Expression of 2 other DEHP targets, hormone-sensitive lipase and phosphoenolpyruvate carboxykinase 1 (Pck1), correlated with reduced aldosterone levels and may account for the inhibitory effect of DEHP on adrenal steroid formation. The angiotensin II and potassium pathways were up-regulated in response to DEHP. In addition, the potassium intermediate/small conductance calcium-activated channel Kcnn2 and 2-pore-domain potassium channel Knck5 were identified as DEHP targets. Based on this gene expression analysis, we measured fatty acid-binding protein 4 and phosphoenolpyruvate carboxykinase 1 in sera from control and DEHP-exposed rats and identified both proteins as putative serum biomarkers of in utero DEHP exposure. These results shed light on molecular targets that mediate DEHP long-term effects and, in doing so, provide means by which to assess past DEHP exposure.

Fetal origin of endocrine dysfunction in the adult: the phthalate model

Di-(2-ethylhexyl) phthalate (DEHP) is a plasticizer with endocrine disrupting properties that is found ubiquitously in the environment as well as in human amniotic fluid, umbilical cord blood, human milk, semen, and saliva. It is used in the industry to add flexibility to polyvinyl chloride-derived plastics and its wide spread use and presence has resulted in constant human exposure through fetal development and postnatal life. Epidemiological studies have suggested an association between phthalate exposures and human reproductive effects in infant and adult populations. The effects of fetal exposure to phthalates on the male reproductive system were unequivocally shown on animal models, principally rodents, in which short term deleterious reproductive effects are well established. By contrast, information on the long term effects of DEHP in utero exposure on gonadal function are scarce, while its potential effects on other organs are just starting to emerge. The present review focuses on these novel findings, which suggest that DEHP exerts more complex and broader disruptive effects on the endocrine system and metabolism than previously thought. This article is part of a Special Issue entitled "CSR 2013".

Evidence that isopropylthioxanthone (ITX) is devoid of anxiolytic and sedative effect

Isopropylthioxanthone (ITX) is a well-known photo-initiator in ultraviolet light-cured inks frequently used in milk packaging materials, yoghurt, ready-to-feed infant formula, and other drinks. Traces of ITX have been found in milk and, as a consequence, there was considerable interest in studying the biological activity of this molecule and its potential hazard for the human health. Although the ITX genotoxic effects have been excluded by the European Food Safety Authority (EFSA), the US Environmental Protection Agency (USEPA) is still examining its possible toxic potential depending on a dose-effect ratio. Little is known about the ITX activity on the function of the central nervous system and cerebral neurotransmitters. Using behavioural, biochemical, and electrophysiological tests, the authors have found that: (1) ITX did not exert an in vivo anxiolytic or sedative effect when administered orally to rats; (2) ITX did not affect the binding characteristics of central and peripheral benzodiazepine receptors studied in vitro; and (3) ITX did not influence the ability of gamma-Aminobutyric acid (GABA) to increase the chloride channel permeability studied by patch clamp technique in a single neuron of cultured cerebellar granule cells.