Short term exposure to di-n-butyl phthalate (DBP) disrupts ovarian function in young CD-1 mice

Abstract

Di-n-butyl phthalate (DBP) is present in many beauty and medical products. Human exposure estimates range from 0.007–0.01 mg/kg/day in the general population and up to 0.233 mg/kg/day in patients taking DBP-coated medications. Levels of phthalates tend to be higher in women, thus, evaluating ovarian effects of DBP exposure is of great importance. Mice were given corn oil (vehicle) or DBP at 0.01, 0.1, and 1000 mg/kg/day (high dose) for 10 days to test whether DBP causes ovarian toxicity. Estrous cyclicity, steroidogenesis, ovarian morphology, and apoptosis and steroidogenesis gene expression were evaluated. DBP exposure decreased serum E2 at all doses, while 0.1DBP increased FSH, decreased antral follicle numbers, and increased mRNA encoding pro-apoptotic genes (Bax, Bad, Bid). Interestingly, mRNAs encoding the steroidogenic enzymes Hsd17b1, Cyp17a1 and Cyp19a1 were increased in all DBP-treated groups. These novel findings show that DBP can disrupt ovarian function in mice at doses relevant to humans.

Environmental pollutants, a possible etiology for premature ovarian insufficiency: a narrative review of animal and human data

“…1). This has been shown for numerous substances: BPA [47], phthalates (DEHP [39, 41], DBP [38]), PAH [41, 96], cigarette smoke [65, 76, 77, 79, 82], pesticides [51–54], dioxins [100], genistein [91], PCB [104]. Secondly, a decreased pool of primordial follicles (situation 5 in Fig.…”

“…No interaction effect was observed.Moyer and Hixon, 2012 [31]Pregnant mice exposed by oral gavage to placebo or 100, 500 or 1000 mg/kg of MEHP during gestational days 17–19.⇘ by 1 month of reproductive lifespan in the highest F1 exposure group (9.8 ± 0.4 compared to 11.1 ± 0.6 months in the control F1 females)Li et al, 2012 [39]60 randomized adult mice in 4 groups exposed to 0, 125, 500 or 2000 mg/kg of DEHP by gavage for 16 weeks, 6 days/weekDEHP arrested granulosa cells in the G0/G1 phases of the cell cycle and ⇗ apoptosis in granulosa cells at 500 and 2000 mg/kgZhang et al, 2013 [35]Subcutaneous injections of DEHP of 20 and 40 μg/kg in newborn mice⇘ number of primordial follicles at puberty and adult age by accelerating follicular recruitment⇘ DNA methylation of maternal imprinted genes (Igf2r, Peg3) in oocytesHannon et al, 2014 [40]Oral exposure of adult mice to DEHP (20 μg at 750 mg/kg/day) every day for 10 or 30 days.⇘ in the number of primordial follicles and ⇗ in the percentage of primary follicles via dysregulation of PI3K signalingLi et al, 2014 [33]Pregnant mice treated with DEHP from 0 to 40 μg/kg/day from 0.5 to the 18.5th day post coitum.⇘ percentage of CpG sites in the differentially methylated regions of the oocytes in F1 mice, heritable to F2.Zhang et al, 2015 [32]Pregnant mice exposed to DEHP, evaluation of the ovarian reserve in offspring generationsDelay of meiosis initiation in F1 fetal ovaries with Stra8 gene hypermethylation and underexpressionAcceleration of follicular recruitment in the F1 and F2 generations responsible for depletion in the primordial follicle pool.Niermann et al, 2015 [34]Pregnant mice exposed to DEHP from 20 μg to 750 mg/kg/day. Evaluation of the number of follicles at D8 and D21 and fertility at 3 and 9 months.⇗ number of pre-antral follicles at D21 with a non-monotonic dose-effect22.2% of mice exposed in utero to 20 μg/kg/day took more than 5 days to become pregnant at 3 monthsSen et al, 2015 [38]Mice exposed to DBP at 0.01, 0.1 and 1000 mg/kg/day for 10 days.⇘ number of antral follicles ⇗ mRNA coding for pro-apoptosis genesLi et al, 2016 [36]Intraperitoneal injection of DEHP in newborn mice, 20 to 40 μg/kg, every 5 days.⇘ percentage of antral follicles.⇗ mRNA of apoptosis genes. Accumulation of ROS.Hannon et al, 2016 [37]Oral exposure of adult mice to DEHP (20 or 500 mg/kg/day) every day for 10 days⇗ BAX/BCL2 ratio in primordial follicles, ⇘ number of primordial follicles, 9 months after exposure. Human Data Messerlian et al, 2016 [42]Assay of phthalate metabolites in urine and antral follicle count, prospective study on 215 patients between 2004 and 2012⇘ antral follicle count in patients whose metabolite assay was in the higher quar...…”

“…Finally, exposing mice during adulthood led to a significant decrease in the number of primordial [37] or antral [38] follicles according to a cell mechanism of apoptosis since there is a significant increase in messenger RNAs coding for pro-apoptotic genes [37, 39] even at low daily doses [38]. Another study found the same results with a decrease in the number of primordial follicles in addition to an increase in the percentage of primary follicles, suggesting an alteration in the beginning of folliculogenesis by accelerating primordial follicle recruitment [40].…”

Effects of oral exposure to the phthalate substitute acetyl tributyl citrate on female reproduction in mice

“…Animals were weighed and dosed daily for 15 consecutive days. All doses were administered orally by placing a pipette tip containing the dosing solution into the mouth past the incisors and into the cheek pouch (Hannon et al, 2014;Sen et al, 2015;Wang et al, 2014). In the absence of biomonitoring data in adult women, we began characterizing the effects of ATBC by exposing animals to levels that were 10-100 times lower than those previously tested in standard studies (CPSC, 2010).…”

“…Average cycle length and percentage of days in proestrus, estrus and metestrus/diestrus were determined. Time spent during each stage was obtained by dividing the total number of days spent in each stage by the total number of days in the study period and multiplying that number by 100 (Hannon et al, 2014;Sen et al, 2015).…”