Placental iron transport under maternal stress: a missing link in foetal programming and mental health.

Gestational environmental stress increased placental iron uptake and accumulation while paradoxically reducing iron transfer to the foetus.

• The effect was observed using human placental samples from mildly stressed and non-stressed mothers, a chronic environmental stress mouse model, and advanced in vitro techniques.
• Iron was taken up and accumulated in the placenta under stress conditions rather than being transferred to the foetus.
• This paradoxical pattern represents a previously unrecognised pathway through which prenatal stress could influence long-term health trajectories in offspring.
• The finding was described as providing insights into 'the sex-specific impact of environmental stress on placental and foetal iron availability.'

The stress-induced reduction in placental iron transfer to the foetus was observed exclusively in female offspring.

• The sex-specific effect was identified across both the mouse model and in vitro experiments.
• No equivalent effect was reported in male offspring.
• The exclusive female effect was reproducible in vitro following both stress exposure and dexamethasone treatment.
• Sex-specificity highlights a differential vulnerability of female foetuses to maternal stress-induced disruption of iron transport.

The stress-related effects on placental iron transport were reproducible in vitro using both stress exposure and dexamethasone treatment.

• Advanced in vitro techniques were employed to model the stress response.
• Dexamethasone, a synthetic glucocorticoid mimicking cortisol effects, recapitulated the stress-induced alteration in iron transport.
• Reproducibility in vitro suggests glucocorticoid signalling as a mechanistic pathway linking maternal stress to placental iron transport disruption.
• The in vitro findings corroborated observations from both the human placental samples and the chronic environmental stress mouse model.

Environmental stress and iron deficiency are described as among the most prevalent nutritional and environmental challenges during pregnancy with potential combined effects on offspring neuropsychiatric risk.

• Chronic maternal anxiety can elevate cortisol levels and trigger inflammatory responses which might subsequently disrupt foetal brain development.
• Iron deficiency during critical windows of gestation can hinder the formation of brain structures and neurotransmitter systems vital for emotional regulation and cognitive function after birth.
• The combined influence of iron deficiency and stress exposure 'may substantially increase the risk of neuropsychiatric disorders in the offspring.'
• Although individual effects of each factor are relatively well understood, 'their interaction during gestation remains unexplored' prior to this study.

A multi-model experimental approach was used, combining human placental tissue, a chronic environmental stress mouse model, and in vitro techniques.

• Human placental samples were collected from mildly stressed and non-stressed mothers.
• A chronic environmental stress mouse model was employed to examine gestational stress effects.
• Advanced in vitro techniques were used to examine mechanistic pathways.
• The study was supported by the Swiss National Science Foundation (SNF grant no. 310030_197408), the NCCR TransCure (grant no. 51NF40_185544), and the Swiss 3R Competence Centre (grant no OC-2019-019).