Pre- and postnatal developmental exposure to the polychlorinated biphenyl mixture aroclor 1221 alters female rat pituitary gonadotropins and estrogen receptor alpha levels

Influence of prenatal hexachlorobenzene, PCB and selenium levels on growth trajectories in the first year of life: Findings from the NEHO birth cohort

Prenatal exposure to endocrine-disrupting chemicals (EDCs) may impact postnatal growth trajectories, increasing the risk of various diseases later in life. This issue is of particular concern in industrially contaminated areas, where environmental matrices contain mixtures of pollutants. This study aimed to evaluate the associations between cord serum concentrations of organochlorine pollutants (hexachlorobenzene-HCB and polychlorinated biphenyls-PCBs) and essential elements (EEs), and weight growth trajectories during the first year of life. We analyzed data from 237 infants enrolled in the Neonatal Environment and Health Outcomes (NEHO) cohort. Using the Group-Based Multivariate Trajectory modeling approach, we identified three distinct growth trajectories from birth to 12 months, classified as "Higher," "Normal," and "Lower." Multinomial regression models were then applied to the whole sample and stratified by sex to assess the associations between individual exposures and the identified child growth trajectories. HCB exposure was associated with an increased risk of reduced growth during the first year of life in both the overall sample and among males [higher vs normal: ORMale = 0.33 (95 % CIMale:0.12;0.87); lower vs normal: ORMale = 2.17 (95 % CIMale:0.94;5.00)]. Conversely, PCB-180 exposure was linked to higher growth only in females [higher vs normal: ORFemale = 24.10 (95 % CIFemale:1.33;438.24)]. Elevated levels of selenium in cord serum were negatively associated with excessive growth [higher vs normal: OROverall = 0.50 (95 % CIOverall: 0.26;0.97)]. These findings suggest sex-specific effects on the growth profile during the first year of life, with different chemical exposures contributing to different outcomes.

Neuroendocrine and Developmental Impacts of Early Life Exposure to EDCs

Polychlorinated biphenyls (PCBs) pose a global challenge to environmental and human health. Although toxic and carcinogenic at higher exposure levels, at lower concentrations they can act as endocrine-disrupting chemicals. Individuals are more vulnerable to endocrine-disrupting effects of PCB exposures during the perinatal period, when the neuroendocrine system is developing, although assessing the full impact of PCB exposure is difficult because of the often-latent onset of adverse effects. The goal of this study was to determine developmental effects of an estrogenic PCB mixture, Aroclor 1221 (A1221), on KNDy and kisspeptin neuron numbers in the hypothalamic arcuate nucleus and anteroventral periventricular nucleus (AVPV), together with measures of hypothalamic-pituitary-gonadal hormones and postnatal development. We conducted RNAscope of kisspeptin, prodynorphin, neurokinin B, and estrogen receptor alpha genes in the P30 hypothalamus. Early-life PCBs caused small but significant changes in development (body weight and anogenital index) but had no effect on puberty. We found sex-specific effects of treatment on serum LH, FSH, and estradiol in a sex- and developmental age-dependent manner. RNAscope results revealed increased prodynorphin in the AVPV of male rats, but no effects on kisspeptin or neurokinin B in AVPV or arcuate nucleus. An unexpected species difference was found: we were unable to detect prodynorphin coexpression with kisspeptin within KNDy neurons in rats, unlike mice, sheep, and primates. These data show that early-life PCBs can induce developmental and hormonal changes that together with other reports showing latent effects on behavior and the hypothalamic-pituitary-gonadal axis, indicate adverse endocrine and neurobehavioral outcomes.

High fat diet-induced obesity and gestational DMBA exposure alter folliculogenesis and the proteome of the maternal ovary†

Obesity and ovotoxicant exposures impair female reproductive health with greater ovotoxicity reported in obese relative to lean females. The mother and developing fetus are vulnerable to both during gestation. 7,12-dimethylbenz[a]anthracene (DMBA) is released during carbon combustion including from cigarettes, coal, fossil fuels, and forest fires. This study investigated the hypothesis that diet-induced obesity would increase sensitivity of the ovaries to DMBA-induced ovotoxicity and determined impacts of both obesity and DMBA exposure during gestation on the maternal ovary. Female C57BL/6 J mice were fed a control or a High Sugar High Fat (45% kcal from fat; 20% kcal from sucrose) diet until ~30% weight gain was attained before mating with unexposed males. From gestation Day 7, mice were exposed intraperitoneally to either vehicle control (corn oil) or DMBA (1 mg/kg diluted in corn oil) for 7 d. Thus, there were four groups: lean control (LC); lean DMBA exposed; obese control; obese DMBA exposed. Gestational obesity and DMBA exposure decreased (P < 0.05) ovarian and increased liver weights relative to LC dams, but there was no treatment impact (P > 0.05) on spleen weight or progesterone. Also, obesity exacerbated the DMBA reduction (P < 0.05) in the number of primordial, secondary follicles, and corpora lutea. In lean mice, DMBA exposure altered abundance of 21 proteins; in obese dams, DMBA exposure affected 134 proteins while obesity alone altered 81 proteins in the maternal ovary. Thus, the maternal ovary is impacted by DMBA exposure and metabolic status influences the outcome.

Endocrine Disruptors and Metabolic Changes: Impact on Puberty Control

OBJECTIVE

This study aims to explore the significant impact of environmental chemicals on disease development, focusing on their role in developing metabolic and endocrine diseases. The objective is to understand how these chemicals contribute to the increasing prevalence of precocious puberty, considering various factors, including epigenetic changes, lifestyle, and emotional disturbances.

METHODS

The study employs a comprehensive review of descriptive observational studies in both human and animal models to identify a degree of causality between exposure to environmental chemicals and disease development, specifically focusing on endocrine disruption. Due to ethical constraints, direct causation studies in human subjects are not feasible; therefore, the research relies on accumulated observational data.

RESULTS

Puberty is a crucial life period with marked physiological and psychological changes. The age at which sexual characteristics develop is changing in many regions. The findings indicate a correlation between exposure to endocrine-disrupting chemicals and the early onset of puberty. These chemicals have been shown to interfere with normal hormonal processes, particularly during critical developmental stages such as adolescence. The research also highlights the interaction of these chemical exposures with other factors, including nutritional history, social and lifestyle changes, and emotional stress, which together contribute to the prevalence of precocious puberty.

CONCLUSION

Environmental chemicals significantly contribute to the development of certain metabolic and endocrine diseases, particularly in the rising incidence of precocious puberty. Although the evidence is mainly observational, it adequately justifies regulatory actions to reduce exposure risks. Furthermore, these findings highlight the urgent need for more research on the epigenetic effects of these chemicals and their wider impact on human health, especially during vital developmental periods.