Quantitative evaluation of alternative mechanisms of blood and testes disposition of di(2-ethylhexyl) phthalate and mono(2-ethylhexyl) phthalate in rats [published erratum appears in Toxicol Sci 1999 Nov;52(1):140] (original) (raw)
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Acta Pharmacologica Et Toxicologica, 2009
In an attempt to establish which compound or compounds are responsible for the testicular damage observed after administration of di-(2-ethylhexyl) phthalate (DEHP) in rats, the effects of the parent compound and five of its major metabolites (mono-(2-ethylhexyl) phthalate (MEHP), 2-ethylhexanol(2-EH), mOnO-(5carboxy-2-ethylpentyl) phthalate, mono-(2-ethyl-5-oxohexyl) phthalate and mono-(2-ethyl-5-hydroxyhexyl) phthalate) were investigated in vivo and in vitro. The concentrations of MEHP and the three MEHP-derived metabolites in plasma were determined after single and multiple oral doses of DEHP. The plasma concentrations and areas under the plasma concentration-time curves (AUC's) of each of the MEHP-derived metabolites were considerably lower than those of MEHP both after single and after repeated administration of 2.7 mmol of DEHP/kg body weight. The mean elimination half-life of MEHP was significantly shorter in animals given repetitive doses than in those given a single dose, but there was no statistically significant difference between the mean AUC values. No testicular damage was observed in young rats given oral doses of 2.7 mmol of DEHP or 2-EH/kg body weight daily for five days. In animals which received corresponding doses of MEHP the number of degenerated spermatocytes and spermatids was increased, whereas no such effects were found in animals given the MEHP-derived metabolites. MEHP was also the only compound that enhanced germ cell detachment from mixed primary cultures of Sertoli and germ cells.
The acute effects of mono(2-ethylhexyl)phthalate (MEHP) on testes of prepubertal Wistar rats
Toxicology Letters, 2001
A single oral dose of 400 mg/kg body weight of mono(2-ethylhexyl)phthalate (MEHP), the testis toxic metabolite of di(2-ethylhexyl)phthalate, was given to 28-day-old male Wistar rats and the testis toxic effects were investigated 3, 6, and 12 h after exposure. Detachment and sloughing of germ cells were observed, and in the Sertoli cells the cytoplasmatic intermediate filament vimentin collapsed. In the immunohistochemical investigation the androgen receptor distribution was unchanged between the control group and treated groups. The expression of the testosterone-repressed-prostatic-message-2 gene in rat testis increased after 3 h, but returned to control levels after 6 and 12 h. Caspase-3 activity increased 3 and 12 h after MEHP exposure. This increase could not be correlated to an increase in DNA fragmentation or increase in apoptotic numbers of germ cells. In conclusion, the effect of MEHP in testis is apparently not involving the androgen receptor. Vimentin localisation in the Sertoli cells, and increased levels of caspase-3 activity appear to be sensitive and early markers of MEHP testis toxicity.
Toxicology and Applied Pharmacology, 2012
The plasticizer di(2-ethylhexyl) phthalate (DEHP) is suspected to induce antiandrogenic effects in men via its metabolite mono(2-ethylhexyl) phthalate (MEHP). However, there is only little information on the kinetic behavior of DEHP and its metabolites in humans. The toxikokinetics of DEHP was investigated in four male volunteers (28-61 y) who ingested a single dose (645± 20 μg/kg body weight) of ring-deuterated DEHP (DEHP-D 4). Concentrations of DEHP-D 4 , of free ring-deuterated MEHP (MEHP-D 4), and the sum of free and glucuronidated MEHP-D 4 were measured in blood for up to 24 h; amounts of the monoesters MEHP-D 4 , ring-deuterated mono(2-ethyl-5-hydroxyhexyl) phthalate and ring-deuterated mono(2-ethyl-5-oxohexyl) phthalate were determined in urine for up to 46 h after ingestion. The bioavailability of DEHP-D 4 was surprisingly high with an area under the concentration-time curve until 24 h (AUC) amounting to 50% of that of free MEHP-D 4. The AUC of free MEHP-D 4 normalized to DEHP-D 4 dose and body weight (AUC/D) was 2.1 and 8.1 times, that of DEHP-D 4 even 50 and 100 times higher than the corresponding AUC/D values obtained earlier in rat and marmoset, respectively. Time courses of the compounds in blood and urine of the volunteers oscillated widely. Terminal elimination half-lives were short (4.3-6.6 h). Total amounts of metabolites in 22-h urine are correlated linearly with the AUC of free MEHP-D 4 in blood, the parameter regarded as relevant for risk assessment.
Toxicology Letters, 2016
Di-(2-propylheptyl) phthalate (DPHP) does not act as a reproductive toxicant or endocrine disruptor in contrast to other phthalates. Considering adverse effects of phthalates to be linked to their metabolism, it was the aim of the present study to investigate in the rat the blood burden of DPHP and its metabolites as a basis for understanding the toxicological behavior of DPHP. Rats were administered single oral doses of DPHP of 0.7 and 100 mg/kg body weight. Concentration-time courses of DPHP and metabolites were monitored in blood. The areas under the concentration-time curves in blood (AUCs), normalized for the dose of DPHP, showed the following order: DPHP < mono-(2-propyl-6-oxoheptyl) phthalate < mono-(2-propyl-6-hydroxyheptyl) phthalate = mono-(2-propylheptyl) phthalate < mono-(2propyl-6-carboxyhexyl) phthalate (cx-MPHP). Glucuronidation of the monoesters accounted for less than 5% of total compounds. The elimination half-lives of the compounds ranged from 2.3 h (DPHP) to 8.2 h (cx-MPHP). The normalized AUCs of the metabolites were lower at the high dose of DPHP than at the low one indicating saturation kinetics of intestinal DPHP hydrolysis. The absence of toxicity to reproduction of DPHP may be related to the comparatively low bioavailability of the parent compound and its metabolites. Abbreviations AUC, concentration-time curve in blood calculated for t→∞; b.w., body weight; cx-MPHP(-d4), non-or ring-deuterated mono-(2-propyl-6-carboxyhexyl) phthalate; cx-MPHP, mono-(2-propyl-6-carboxyhexyl) phthalate; cx-MPHP-d4, ring-deuterated mono-(2-propyl-6-carboxyhexyl) phthalate; DEHP, di-(2-ethylhexyl) phthalate; DINP, di-isononyl phthalate; DPHP(-d4), non-or ring-deuterated di-(2-propylheptyl) 3 phthalate; DPHP, di-(2-propylheptyl) phthalate; DPHP-d4, ring-deuterated di-(2propylheptyl) phthalate; MEHP, mono-(2-ethylhexyl) phthalate; MPHP(-d4), non-or ring-deuterated mono-(2-propylheptyl) phthalate; MPHP, mono-(2-propylheptyl) phthalate; MPHP-d4, ring-deuterated mono-(2-propylheptyl) phthalate; OH-MPHP(-d4), non-or ring-deuterated mono-(2-propyl-6-hydroxyheptyl) phthalate; OH-MPHP, mono-(2-propyl-6-hydroxyheptyl) phthalate; OH-MPHP-d4, ring-deuterated mono-(2propyl-6-hydroxyheptyl) phthalate; oxo-MPHP(-d4), non-or ring-deuterated mono-(2propyl-6-oxoheptyl) phthalate; oxo-MPHP, mono-(2-propyl-6-oxoheptyl) phthalate; oxo-MPHP-d4, ring-deuterated mono-(2-propyl-6-oxoheptyl) phthalate; t1/2, half-life of the elimination phase
Differential Effects of Phthalates on the Testis and the Liver
Biology of Reproduction, 2005
Phthalates have been shown to elicit contrasting effects on the testis and the liver, causing testicular degeneration and promoting abnormal hepatocyte proliferation and carcinogenesis. In the present study, we compared the effects of phthalates on testicular and liver cells to better understand the mechanisms by which phthalates cause testicular degeneration. In vivo treatment of rats with di-(2-ethylhexyl) phthalate (DEHP) caused a threefold increase of germ cell apoptosis in the testis, whereas apoptosis was not changed significantly in livers from the same animals. Western blot analyses revealed that peroxisome proliferator-activated receptor (PPAR) alpha is equally abundant in the liver and the testis, whereas PPAR gamma and retinoic acid receptor (RAR) alpha are expressed more in the testis. To determine whether the principal metabolite of DEHP, mono-(2-ethylhexyl) phthalate (MEHP), or a strong peroxisome proliferator, 4-chloro-6(2,3-xylindino)-2-pyrimidinylthioacetic acid (Wy-14,643), have a differential effect in Sertoli and liver cells by altering the function of RAR alpha and PPARs, their nuclear trafficking patterns were compared in Sertoli and liver cells after treatment. Both MEHP and Wy-14,643 increased the nuclear localization of PPAR alpha and PPAR gamma in Sertoli cells, but they decreased the nuclear localization of RAR alpha, as previously shown. Both PPAR alpha and PPAR gamma were in the nucleus and cytoplasm of liver cells, but RAR alpha was predominant in the cytoplasm, regardless of the treatment. At the molecular level, MEHP and Wy-14,643 reduced the amount of phosphorylated mitogen-activated protein kinase (activated MAPK) in Sertoli cells. In comparison, both MEHP and Wy-14,643 increased phosphorylated MAPK in liver cells. These results suggest that phthalates may cause contrasting effects on the testis and the liver by differential activation of the MAPK pathway, RAR alpha, PPAR alpha, and PPAR gamma in these organs.
Differential Effects of Phthalates on the Testis and the Liver1
Biology of Reproduction, 2005
Phthalates have been shown to elicit contrasting effects on the testis and the liver, causing testicular degeneration and promoting abnormal hepatocyte proliferation and carcinogenesis. In the present study, we compared the effects of phthalates on testicular and liver cells to better understand the mechanisms by which phthalates cause testicular degeneration. In vivo treatment of rats with di-(2-ethylhexyl) phthalate (DEHP) caused a threefold increase of germ cell apoptosis in the testis, whereas apoptosis was not changed significantly in livers from the same animals. Western blot analyses revealed that peroxisome proliferator-activated receptor (PPAR) ␣ is equally abundant in the liver and the testis, whereas PPAR␥ and retinoic acid receptor (RAR) ␣ are expressed more in the testis. To determine whether the principal metabolite of DEHP, mono-(2-ethylhexyl) phthalate (MEHP), or a strong peroxisome proliferator, 4-chloro-6(2,3-xylindino)-2-pyrimidinylthioacetic acid (Wy-14,643), have a differential effect in Sertoli and liver cells by altering the function of RAR␣ and PPARs, their nuclear trafficking patterns were compared in Sertoli and liver cells after treatment. Both MEHP and Wy-14,643 increased the nuclear localization of PPAR␣ and PPAR␥ in Sertoli cells, but they decreased the nuclear localization of RAR␣, as previously shown. Both PPAR␣ and PPAR␥ were in the nucleus and cytoplasm of liver cells, but RAR␣ was predominant in the cytoplasm, regardless of the treatment. At the molecular level, MEHP and Wy-14,643 reduced the amount of phosphorylated mitogen-activated protein kinase (activated MAPK) in Sertoli cells. In comparison, both MEHP and Wy-14,643 increased phosphorylated MAPK in liver cells. These results suggest that phthalates may cause contrasting effects on the testis and the liver by differential activation of the MAPK pathway, RAR␣, PPAR␣, and PPAR␥ in these organs. di-(2-ethylhexyl) phthalate, di-isonanoyl phthalate, environment, liver, mitogen activated protein kinase, p38, peroxisome proliferator activated receptor, Sertoli cells, testis, toxicology
Food and Chemical Toxicology, 2020
Phthalates are widely used as plasticisers in flexible plastics and containers for food and personal care products (PCPs) and contaminates foods and PCPs. A human biomonitoring (BM) study was performed to study exposure of chemicals from foods and PCPs. For two 24-h periods, adult volunteers (n = 144) in Norway kept diaries on food eaten and usage of PCPs, and collected 24-h urine. Aggregated exposure to di(2-ethylhexyl) phthalate (DEHP) from dietary and PCPs was estimated by Monte-Carlo simulation using Oracle Crystal Ball©. Simulated urinary concentrations using physiologically based pharmacokinetic (PBPK) models were compared with measured urinary metabolites of DEHP, mono-2-ethylhexyl phthalate (MEHP), mono-2-ethyl-5-hydroxyhexyl phthalate (MEHHP), mono-2-ethyl-5-oxohexyl phthalate (MEOHP) and mono-2-ethyl 5-carboxypentyl phthalate (MECCP). DEHP exposure from food are approximately 10 times higher than exposure than from PCPs. The main contributors to dietary exposure are dairy, grain, fruits and vegetables, meat and fish. Body lotion contribute most to the exposure of DEHP from PCPs. Forward-dosimetry gives good convergence with 24-h urinary concentrations of simulated and measured BM data. The measured concentration of the MECCP metabolite correlated well with simulated high exposure, while the measured concentrations of MEHP, MEHHP and MEOHP partly overlapped with both simulated low, medium and high metabolite exposure.
Environmental health …, 2009
Background Endocrine-disrupting effects of phthalates are understood primarily from in utero exposures within the fetal rat testis. Nevertheless, their path of action, dose–response character, and cellular target(s) within the fetal testis are not known.Objectives In this study we investigated the effects of di-(2-ethylhexyl) phthalate (DEHP), mono-(2-ethylhexyl) phthalate (MEHP), and several of their metabolites on the development of organo-cultured testes from rat fetus.Methods We removed testes from 14.5-day-old rat fetuses and cultured them for 1–3 days with or without DEHP, MEHP, and the metabolites.Results DEHP (10−5 M) produced a proandrogenic effect after 3 days of culture, whereas MEHP disrupted testis morphology and function. Leydig cells were the first affected by MEHP, with a number of them being inappropriately located within some seminiferous tubules. Additionally, we found a time- and dose-dependent reduction of testosterone. By 48 hr, gonocyte proliferation had decreased, whereas apoptosis increased. Sertoli cell number was unaffected, although some cells appeared vacuolated, and production of anti-Müllerian hormone decreased in a time- and dose-dependent manner. The derived metabolite mono-(2-ethyl-5-hydroxyhexyl) phthalate was the only one to cause deleterious effects to the rat fetal testis in vitro.Conclusion We hope that this in vitro method will facilitate the study of different phthalate esters and other endocrine disruptors for direct testicular effects.