A whole body autoradiographic study on the distribution of 14C-labelled di-(2-ethylhexyl)phthalate in mice

Endocrine disrupting chemicals: Friend or foe to brown and beige adipose tissue?

The effects of Endocrine Disrupting Chemicals (EDCs) on the current obesity epidemic is a growing field of interest. Numerous EDCs have shown the potential to alter energy metabolism, which may increase the risk of obesity, in part, through direct actions on adipose tissue. While white adipose tissue has historically been the primary focus of this work, evidence of the EDC-induced disruption of brown and beige adipose tissues continues to build. Both brown and beige fat are thermogenic adipose depots rich in mitochondria that dispense heat when activated. Due to these properties, brown and beige fat are implicated in metabolic diseases such as obesity, diabetes, and cachexia. This review delves into the current literature of different EDCs, including bisphenols, dioxins, air pollutants, phthalates, and phytochemicals. The possible implications that these EDCs have on thermogenic adipose tissues are covered. This review also introduces the possibility of using brown and beige fat as a therapeutic target organ by taking advantage of some of the properties of EDCs. Collectively, we provide a comprehensive discussion of the evidence of EDC disruption in white, brown, and beige fat and highlight gaps worthy of further exploration.

Determination of modifications in rat liver due to phthalate uptake by SAM, RS, and ICP-OES

The use of phthalates as plasticizers has been omnipresent, especially in cosmetics and food packaging, despite the proven effects on some organs of humans and animals. Therefore, alterations in living organisms due to phthalate exposure attract the attention of many scientists. Here, we demonstrate a mechanical and chemical investigation of the mentioned effects of di(2-ethylhexyl)phthalate (DEHP) and dibutyl phthalate (DBP) on rat liver by utilizing scanning acoustic microscopy (SAM), Raman spectroscopy (RS) and inductively coupled plasma optical emission spectrometry (ICP-OES) for the first time in the literature, as far as we know. The combined analysis gives insights into the degree of modification in the tissue components and which chemicals lead to these modifications. Our study shows that the acoustic impedance values of tissues of DEHP and DBP delivered mother rats are higher than those of tissues of the control mother rat, while the acoustic impedance values of tissues of offspring rats of DEHP and DBP delivered mother rats do not differ significantly from those of tissues of the control offspring rats of the control mother rat. Besides, RS analysis shows how the incorporation of DEHP into liver tissues changes the configuration and conformation of lipids and fatty acids. ICP-OES results show increased element levels within the tissues of DEHP and DBP delivered rats. Therefore, we can say that phthalates cause modifications within the liver. This study is a preliminary effort to investigate tissues with a mechano-chemical probe.

Effects of pubertal exposure to low doses of di-(2-ethylexyl)phthalate on reproductive behaviors in male mice

Reproductive behaviors are tightly regulated by sex steroid hormones. Interference with these hormones or their neural signaling pathways leads to behavioral alterations. We have previously shown that oral exposure of adult male mice to di(2-ethylhexyl) phthalate (DEHP), an organic environmental endocrine disruptor, altered sexual behavior. In this study, we examined the effects of pubertal exposure to DEHP and analyzed whether pubertal and adult exposures to DEHP trigger long-term effects. For pubertal exposure, male mice were exposed orally to the vehicle or DEHP at 5 or 50 μg/kg/d from postnatal day (PND) 30 to PND60. Exposure was arrested and animals were analyzed on PND120. They exhibited normal olfactory preference but showed modified emission of ultrasonic vocalizations. DEHP exposure also affected partner preference and mating components. These modifications were associated with normal circulating testosterone levels and weight of androgen-sensitive tissues. In contrast, androgen receptor (AR) protein amount was reduced in the hypothalamic preoptic area in particular for the DEHP-50 group. Pubertal exposure also increased the anxiety-state level without changing circadian activity. When adult male mice were exposed to DEHP at the same doses from PND60 to PND105 and analyzed two months later, no effects of treatment on reproductive and anxiety-related behaviors or hypothalamic AR protein amount were seen. Our data show that pubertal exposure of male mice to DEHP induces long-term behavioral changes in contrast to the adult exposure. This highlights the sensitivity of the nervous system to low doses of DEHP during the critical period of puberty.

Carryover Effects of Acute DEHP Exposure on Ovarian Function and Oocyte Developmental Competence in Lactating Cows

We examined acute exposure of Holstein cows to di(2-ethylhexyl) phthalate (DEHP) and its carryover effects on ovarian function and oocyte developmental competence. Synchronized cows were tube-fed with water or 100 mg/kg DEHP per day for 3 days. Blood, urine and milk samples were collected before, during and after DEHP exposure to examine its clearance pattern. Ovarian follicular dynamics was monitored through an entire estrous cycle by ultrasonographic scanning. Follicular fluids were aspirated from the preovulatory follicles on days 0 and 29 of the experiment and analyzed for phthalate metabolites and estradiol concentration. The aspirated follicular fluid was used as maturation medium for in-vitro embryo production. Findings revealed that DEHP impairs the pattern of follicular development, with a prominent effect on dominant follicles. The diameter and growth rate of the first- and second-wave dominant follicles were lower (P < 0.05) in the DEHP-treated group. Estradiol concentration in the follicular fluid was lower in the DEHP-treated group than in controls, and associated with a higher number of follicular pathologies (follicle diameter >25 mm). The pattern of growth and regression of the corpus luteum differed between groups, with a lower volume in the DEHP-treated group (P < 0.05). The follicular fluid aspirated from the DEHP-treated group, but not the controls, contained 23 nM mono(2-ethylhexyl) phthalate. Culturing of cumulus oocyte complexes in the follicular fluid aspirated from DEHP-treated cows reduced the proportion of oocytes progressing to the MII stage, and the proportions of 2- to 4-cell-stage embryos (P < 0.04) and 7-day blastocysts (P < 0.06). The results describe the risk associated with acute exposure to DEHP and its deleterious carryover effects on ovarian function, nuclear maturation and oocyte developmental competence.

Effect of di-(2-ethylhexyl) phthalate and mono-(2-ethylhexyl) phthalate on in vitro developmental competence of bovine oocytes

In the last decade, potential exposure of humans and animals to industrial chemicals and pesticides has been a growing concern. In the present study, di-(2-ethylhexyl) phthalate (DEHP) and mono-(2-ethylhexyl) phthalate (MEHP) were used to model the effects of endocrine-disrupting compounds and their risk in relation to early embryonic losses. Exposure of cumulus oocyte complexes during maturation to 50 μM MEHP reduced the proportion of oocytes that underwent nuclear maturation (p < 0.05) and increased the proportion of apoptotic oocytes (p < 0.05). Furthermore, phthalates reduced cleavage rate in the MEHP-treated group (p < 0.05) and the proportion of embryos developing to the blastocyst stage in both DEHP- and MEHP-treated groups (p < 0.05). The total cell count for blastocysts developing from MEHP-treated oocytes was lower than in controls (p < 0.05). Exposure of oocytes to MEHP during maturation reduced (p < 0.05) the expression of ASAH1 (an anti-apoptotic factor), CCNA2 (involved in cell cycle control), and POU5F1 (responsible for pluripotency) in matured oocytes. Furthermore, the reduced mRNA expression of POU5F1 and ASAH1 lasted into two-cell stage embryos (p < 0.05). Phthalate-induced alterations in POU5F1, ASAH1, and CCNA2 expression might explain in part the reduced developmental competence of MEHP-treated oocytes.

Effect of in utero exposure to di-(2-ethylhexyl)phthalate: distribution in the rat fetus and testosterone production by rat fetal testis in culture

DEHP is known to cause reproductive toxicity in rats, particularly during the neonatal period. Pregnant and brood rats were treated by gavage with 750 mg/kgb.w./day DEHP starting on GD14 within PND4. Two hours after (14)C-DEHP administration on GD15, GD18, GD21 and PND4, the radioactivity content was measured in the dams blood and in the liver, gonads and carcass of the offspring. The radioactivity concentration recovered in the fetuses was one or two order of magnitude lower than the concentration found in the dam plasma. A low proportion of radioactivity was present in fetal gonads, ca. 2%, 5% and 3.6% on GD18, GD21 and PND4, respectively. The effect on testosterone production of DEHP and its metabolites (MEHP, metabolites VI and IX) was assessed in fetal testis cultures using a dose-range which included the maximal exposure observed in vivo. None of the compounds affected testosterone production. Thus, DEHP and/or its metabolites appear to cross the placental barrier, reach the fetal gonads. In vitro, neither DEHP nor its main metabolites decreased the testosterone production.

Application of whole-body autoradiography in toxicology

Whole-body autoradiography enables the drugs and toxicants to be distributed throughout the animal. Good results are obtained with this technique. However, certain artifacts can occur that could lead to misinterpretation, and these must be known. These artifacts are described. From the metabolic point of view, autoradiography provides data on the distribution kinetics of a compound and the elimination of radioactivity in various organs. These data are a guide for quantitative research into the metabolism of a compound. From the toxicological point of view, it must be admitted that the main purpose of this technique is to reveal the sites of retention of radioactivity. Such specific organ retention could be the consequence of the activation of a minor metabolite into a very reactive compound. If this is so, it is a specific organ effect which could not be studied by other techniques and could lead the way to a more specific organ effect which could not be studied by other techniques and could lead the way to a more appropriate line of research in the study of chronic toxicity. However, it must be recalled that the fact that a compound is retained by a specific organ does not always mean that the compound exerts a toxic effect upon the said organ. With this technique, distribution study can be performed on pregnant animals, and it provides us with more data concerning the transplacental passage of radioactive metabolites. All these aspects of the technique clearly indicate that whole-body autoradiography should be insisted upon during the early stages of development of new molecules. Successive experiments could then lead to selecting the best experimental conditions for metabolic pharmacokinetics and studies in toxicology.

Inhibitory effect of ricin on the development of preimplantation mouse embryos

Preimplantation mouse embryos were exposed to ricin, a plant toxin, in vitro and in vivo. The effect was evaluated by morphological observations of the exposed embryos as well as by means of protein synthesis. Ricin was highly toxic to the preimplantation mouse embryo in vitro, the effect being greater on the 2-cell than on the 4-8 cell stage. Intraperitoneal injection of ricin induced a small number of fetuses with exencephaly.