Identification of Rat foreskin biomarkers of in utero dibutyl phthalate exposure
Ontology highlight
ABSTRACT: Dibutyl phthalate was administered to pregnant Sprague Dawley rats from gestational days 16-20 at either a 100 mg/kg/day or 500 mg/kg/day dose level. This timeframe covers the reproductive masculinization window which corresponds to increased androgen signalling. Dibutyl phthalate has been shown to disrupt testosterone production leading to male reproductive abnormalities. As such, we selected this exposure window for our study and examined gene expression changes in the male rat foreskin, which expresses the androgen receptor. We collected tissue samples at both gestational day 20 to identify gene expression changes immediately after exposure, and postnatal day 5 to identify gene expression changes persisting after birth using microarray analysis (Illumina RatRef 12 Bead Chips). To determine whether gene expression changes were brought on by decreased androgen signalling or additional effects of dibutyl phthalate exposure, we exposed rats to the potent androgen receptor antagonist flutamide (5 mg/kg/day) during the same period of development. Gene expression changes were compared to determine which were brought on by disruption of androgen signalling and which were the result of other aspects of chemical exposure. The flutamide exposure study consisted of seven control dams administered corn oil and seven dams treated with 5 mg/kg/day flutamide. Two foreskin samples per litter were pooled for gene expression microarray analysis using the Affymetrix Gene 1.0 ST Array.
Project description:Dibutyl phthalate was administered to pregnant Sprague Dawley rats from gestational days 16-20 at either a 100 mg/kg/day or 500 mg/kg/day dose level. This timeframe covers the reproductive masculinization window which corresponds to increased androgen signalling. Dibutyl phthalate has been shown to disrupt testosterone production leading to male reproductive abnormalities. As such, we selected this exposure window for our study and examined gene expression changes in the male rat foreskin, which expresses the androgen receptor. We collected tissue samples at both gestational day 20 to identify gene expression changes immediately after exposure, and postnatal day 5 to identify gene expression changes persisting after birth using microarray analysis (Illumina RatRef 12 Bead Chips). To determine whether gene expression changes were brought on by decreased androgen signalling or additional effects of dibutyl phthalate exposure, we exposed rats to the potent androgen receptor antagonist flutamide (5 mg/kg/day) during the same period of development. Gene expression changes were compared to determine which were brought on by disruption of androgen signalling and which were the result of other aspects of chemical exposure.
Project description:Dibutyl phthalate was administered to pregnant Sprague Dawley rats from gestational days 16-20 at either a 100 mg/kg/day or 500 mg/kg/day dose level. This timeframe covers the reproductive masculinization window which corresponds to increased androgen signalling. Dibutyl phthalate has been shown to disrupt testosterone production leading to male reproductive abnormalities. As such, we selected this exposure window for our study and examined gene expression changes in the male rat foreskin, which expresses the androgen receptor. We collected tissue samples at both gestational day 20 to identify gene expression changes immediately after exposure, and postnatal day 5 to identify gene expression changes persisting after birth using microarray analysis (Illumina RatRef 12 Bead Chips). To determine whether gene expression changes were brought on by decreased androgen signalling or additional effects of dibutyl phthalate exposure, we exposed rats to the potent androgen receptor antagonist flutamide (5 mg/kg/day) during the same period of development. Gene expression changes were compared to determine which were brought on by disruption of androgen signalling and which were the result of other aspects of chemical exposure.
Project description:Dibutyl phthalate was administered to pregnant Sprague Dawley rats from gestational days 16-20 at either a 100 mg/kg/day or 500 mg/kg/day dose level. This timeframe covers the reproductive masculinization window which corresponds to increased androgen signalling. Dibutyl phthalate has been shown to disrupt testosterone production leading to male reproductive abnormalities. As such, we selected this exposure window for our study and examined gene expression changes in the male rat foreskin, which expresses the androgen receptor. We collected tissue samples at both gestational day 20 to identify gene expression changes immediately after exposure, and postnatal day 5 to identify gene expression changes persisting after birth using microarray analysis (Illumina RatRef 12 Bead Chips). To determine whether gene expression changes were brought on by decreased androgen signalling or additional effects of dibutyl phthalate exposure, we exposed rats to the potent androgen receptor antagonist flutamide (5 mg/kg/day) during the same period of development. Gene expression changes were compared to determine which were brought on by disruption of androgen signalling and which were the result of other aspects of chemical exposure. Two foreskin samples per litter were pooled for gene expression microarray analysis using the Illumina ratRef-12 v1.0 expression beadchip.
Project description:High dose level dibutyl phthalate (DBP) exposure of fetal rat testes in vivo inhibits testosterone production (i.e. endocrine disruption). Here, fetal testis mRNA levels were profiled following exposure to a DBP dose level that did not significantly reduce testosterone levels. The goal was to identify the constellation of gene expression changes that do not correlate with endocrine disruption. Fischer 344 rats were exposed via oral gavage of the dam to vehicle (corn oil) or 50 mg/kg (body weight) DBP daily from gestational day (GD) 12 to 20. The day after mating was defined as gestational day 0. Six hours after the final exposure on GD20, fetal testes were dissected and mRNA levels quantified using Affymetrix Rat Expression 230 2.0 microarrays.
Project description:2-Isopropylthioxanthone (2-ITX), a photoinitiator used in ink for printing of food packaging materials, has been detected in products like milk and fruit beverages. Previous in vitro research demonstrated 2-ITX to 1) exert agonistic effects on the aryl hydrocarbon receptor (AhR), 2) exert antagonistic effects on both the androgen (AR) and estrogen receptor (ER), and 3) to increase aromatase activity. To validate these findings in vivo, male rats were treated by gavage with 50, 150 or 500 mg 2-ITX/kg b.w. per day from postnatal day 23 to 53. For comparison, other groups were treated with 50 ng TCDD/kg b.w./day (AhR agonist), 30 mg bicalutamide/kg b.w./day (Casodex, AR antagonist) or 50 mg flutamide/kg b.w./day (AhR agonist and AR antagonist). 2-ITX, from the lowest dose onwards, decreased the weight of the ventral prostate, and from the middle dose onwards the weight of the seminal vesicles and coagulating gland. The highest dose of 2-ITX reduced the number of spermatozoa in the cauda of the epididymis. Similar effects, but more severe, were induced by flutamide and bicalutamide. Epididymal weight, caput sperm count and preputial separation were negatively affected by Casodex and flutamide but not by 2-ITX. The two highest doses of 2-ITX as well as TCDD increased liver weight. Whole genome mRNA expression profiling of the liver revealed similarity between the effects of 2-ITX and flutamide. In addition, many genes induced by TCDD were also induced by 2-ITX and flutamide. These results demonstrate 2-ITX to express AhR agonistic and AR antagonistic activities, both in vitro and in vivo.
Project description:RNA-seq analysis was conducted as part of an experiment investigating the effects of the phthalate, dipentyl phthalate (DPeP), on the rat fetal testis. The goal of the study was to test what gene expression responses occurred in a dose-dependent fashion, and which were most sensitive, following exposure to 1, 11, 100, or 300 mg/kg/d DPeP from gestational day (GD) 17-21.
Project description:Provided later Pregnant Fisher 344 rats will be purchased from Charles River Laboratories, Inc. and delivered to CIIT on gestational day (GD) 7 (GD0 = day first vaginal plug positive). At gestational day 12 (GD12), the dams will be exposed once/day until GD20 to 50 mg/kg dibutyl phthalate (DBP) in corn oil vehicle via oral gavage. Each dose group will contain 4-6 vehicle control or phthalate treated dams. Groups of animals will be sacrificed at GD20, postnatal day (PND) 35, and PND90 for endpoint analysis. At GD20, treated and control animals will be examined for various endpoints including body weight, testicular histopathology, gene expression profile via microarray analysis, and anogenital distance (AGD). AGD (at parturition; PND1) and nipple number/location (at PND14 and day of sacrifice) will be determined on animals in the postnatal groups. At PND35 or 90, one male from each in utero corn oil vehicle or DBP exposed group will receive a second gavage of either corn oil or 500 mg/kg DBP. 6 hours after the second gavage, the following endpoints will be examined: 1) testis histopathology; 2) spermatid head quantification (PND90 only); 3) testis and body weights; 5) genome-wide gene expression (via microarray); and 6) germ cell apoptosis (TUNEL assay).
Project description:With the advent of high information content technologies, especially microarrays, it is pertinent to determine the impact of molecular data on the NOAELs. Consequently, we conducted an integrative study to identify a no transcriptomic effect dose using microarray analyses coupled with qPCR and determined how this correlated with the NOAEL. We assessed the testicular effects of the antiandrogen, flutamide (FM), in a rat 28-day toxicity study using doses of 0.2-30 mg/kg/day. Concerning molecular data, we observed differential gene expression starting from 1 mg/kg/day and a deregulation of more than 1500 genes at 30 mg/kg/day. Dose-related changes were identified for the major pathways associated with the testicular lesion (eg fatty acid metabolism), that were confirmed by qPCR. These data, along with standard measurements supported the no effect dose of 0.2 mg/kg/day.
Project description:Dibutyl phthalate (DBP), di-2-ethylhexyl phthalate (DEHP), and benzyl butyl phthalate (BBP) are three phthalates commonly found in consumer products, including the plastic coating of pharmaceuticals and personal care products. Folliculogenesis, a tightly regulated process occurring in the ovary, is the maturation of an immature primordial follicle to a mature antral follicle. Follicles house the oocyte and antral follicles specifically play a crucial role in ovarian steroidogenesis and ovulation. DBP, BBP, and DEHP have been associated with inhibited antral follicle growth in vitro, decreased ovulation rates in vitro, and decreased antral follicle counts in women. However, little is known about the effects of a three-phthalate mixture on antral follicles in vivo. The objective of this study was to evaluate the effects of a human relevant mixture of DBP, BBP, and DEHP on ovarian follicles through proteome profiling analysis. CD-1 female mice (60 days old) were pipet fed tocopherol stripped corn oil (vehicle control) only or a phthalate mixture (52% DBP, 36% DEHP, and 12% BBP dissolved in vehicle) which modeled human follicular fluid concentrations. The mice were treated with 32µg/kg/day (PHT Mix 32; cumulative estimate in general population) and 500µg/kg/day (PHT Mix 500; cumulative estimate in occupationally exposed individuals) for 10 consecutive days. Proteome profiling of antral follicles (>250µm) was performed via label-free tandem mass spectrometry. A total of 5,417 antral follicle proteins were identified in the three groups, of which 194 were differentially abundant between the vehicle and PHT Mix 32 group, and 136 between the vehicle and PHT Mix 500 group. Gene ontology analysis revealed that the two treatments of the phthalate mixture upregulate and downregulate distinctive processes, supporting non-monotonic effects of phthalates on the antral follicle proteome. Taken together, these results reveal that a human relevant mixture of DBP, BBP, and DEHP alters the antral follicle proteome and merits further evaluation to elucidate the molecular mechanisms by which phthalates cause negative reproductive outcomes.