Sow’s Milk Shields the Newborn Uterus From Chemical Disruption, Gene Study Reveals

A new study from Polish researchers has revealed that what newborn piglets eat in their first days of life can fundamentally change how their developing uteruses react to hormone-disrupting chemicals. The findings, published in BMC Genomics, suggest that early nutrition is not merely a source of calories but an active biological force that shapes the molecular defenses of reproductive tissue during one of the most vulnerable windows of development. The work offers a striking glimpse into how feeding decisions made in the first days after birth may echo through the genome, potentially influencing lifelong reproductive health.

The research team, led by Anna Nynca of the University of Warmia and Mazury in Olsztyn, together with colleagues from the Polish Academy of Sciences, Jagiellonian University, and the University of Rzeszow, focused on a class of chemicals known as endocrine-active compounds, or EACs. These substances, which include industrial chemicals and pharmaceutical agents, can mimic, block, or otherwise interfere with the body’s hormonal signaling. Because hormones orchestrate nearly every aspect of early reproductive development, scientists have become increasingly concerned that EAC exposure during critical early-life windows may act as a developmental toxicant, quietly rewiring tissues at the molecular level long before any outward symptoms appear.

To probe this question, the researchers turned to the neonatal pig, a species widely regarded as one of the most translationally relevant animal models for human reproductive development. The pig uterus undergoes a process called adenogenesis in the days after birth, in which the glands that will later nourish embryos form and mature within the uterine wall. This developmental program depends on precisely timed hormonal cues, making it exquisitely sensitive to chemical interference. The pig’s reproductive anatomy, hormonal cycles, and genomic architecture all resemble the human situation far more closely than the commonly used rodent models, which is why the team chose it as their experimental platform.

The experimental design was elegant in its simplicity. Newborn female piglets were divided into two feeding groups: one nursed naturally from their mothers, receiving sow’s milk, and the other raised on infant formula. On postnatal day 10, a period when uterine development is in full swing, the researchers collected uterine tissue from both groups. They then sliced the tissue into explants, thin sections that can be kept alive in laboratory culture dishes, and exposed these explants to three different endocrine-active compounds. The explant approach allowed the team to control chemical exposure precisely while keeping the tissue in a near-physiological state, and they confirmed tissue viability across the culture period by measuring lactate dehydrogenase release.

The three compounds represented distinct mechanistic threats. The first, 2-hydroxyflutamide, is an anti-androgen, a substance that blocks the receptors through which male hormones exert their effects. The second, 4-tert-octylphenol, is an industrial chemical used in the production of detergents and plastics, known to mimic estrogen. The third, HPTE, is a metabolite of the banned pesticide methoxychlor and acts as a disruptor of both estrogenic and androgenic signaling. By testing all three against uterine tissue from both feeding groups, the researchers could ask a deceptively simple question: does the same chemical produce the same molecular response in tissue that has been nourished differently?

The answer, revealed through a comprehensive transcriptomic analysis, was a resounding no. Using RNA sequencing, the team mapped the coding genes, long non-coding RNAs, and microRNAs expressed in each tissue sample, comparing treated explants against untreated controls. They found that the feeding regimen consistently shaped uterine responses to all three tested compounds. In the uteri of sow-fed piglets, the transcriptional upheaval triggered by 4-tert-octylphenol and HPTE was markedly attenuated, as if sow’s milk had equipped the tissue with a buffer against chemical disruption. In contrast, uterine tissue from formula-fed piglets displayed far greater transcriptional sensitivity, with many more genes swinging up or down in response to the same chemical challenge.

The affected genes were not random. Functional analysis showed that the dysregulated transcripts clustered around biological processes central to uterine development itself: cell-cycle regulation, morphogenesis, and the organization of cilia, the hair-like cellular projections that play roles in tissue patterning and fluid movement. All three processes are essential to adenogenesis, the gland-forming program underway in the neonatal uterus. This convergence suggests that endocrine-active compounds do not merely perturb isolated genes but strike at the very machinery that builds the reproductive organ, raising the possibility that early exposure could leave lasting structural and functional imprints.

Perhaps the most surprising twist came from the microRNA data. MicroRNAs are short regulatory RNA molecules that fine-tune gene expression after transcription, and their production depends on a processing machinery involving the proteins Drosha, DGCR8, and Dicer, whose abundance the team also measured. While sow-fed tissue showed a muted response at the level of messenger RNA, it exhibited more pronounced microRNA responses to chemical exposure. Notably, the microRNA remodeling induced by HPTE was not prevented by natural feeding, indicating that sow’s milk protects some layers of gene regulation but not others. This layered, diet-dependent pattern of protection suggests that the molecular consequences of early nutrition are far more nuanced than a simple shield-versus-vulnerability model would predict.

The broader implications reach well beyond pig farming. Infant formula is a nutritional staple for millions of human babies, and human infants are simultaneously exposed to endocrine-active compounds through plastics, personal care products, food contaminants, and pharmaceuticals. If early nutrition genuinely modulates the molecular responsiveness of developing reproductive tissue, as this study indicates, then the interplay between infant feeding and environmental chemical exposure deserves far closer scrutiny. The authors emphasize that their results support the hypothesis that feeding regimen and the associated rearing conditions are linked to differences in the molecular responsiveness of neonatal uterine tissue to endocrine challenge, a conclusion that invites parallel investigation in human developmental biology.

The study, funded by the National Science Centre of Poland and conducted under approved ethical protocols, also showcases the power of modern multi-omic approaches, integrating coding transcriptomes, long non-coding RNA profiles, microRNA sequencing, and protein-level validation of the miRNA-processing machinery. As endocrine disruptors continue to permeate the modern environment, research of this kind points toward a compelling and actionable idea: the earliest nutritional choices we make for the youngest members of our species may help determine how resilient their bodies are to the chemical challenges of the world they inherit. The neonatal uterus, it turns out, listens carefully to what it is fed, and its genomic response to toxic insult may be written, at least in part, by the very first meals of life.

Subject of Research: The influence of early neonatal nutrition on transcriptomic and miRNA responses of the developing uterus to endocrine-active compounds in a porcine model

Article Title: Early nutrition modulates transcriptomic responses to endocrine-active compounds in neonatal porcine uterine explants

Article References: Nynca, A., Swigonska, S., Molcan, T., Wojtaszek, M., Grzesiak, M., Koziorowska, A., Koziorowski, M., Slomczynska, M., & Knapczyk-Stwora, K. (2026). Early nutrition modulates transcriptomic responses to endocrine-active compounds in neonatal porcine uterine explants. BMC Genomics. https://doi.org/10.1186/s12864-026-13348-9

Image Credits: AI Generated

DOI: 10.1186/s12864-026-13348-9

Keywords: endocrine disruptors, neonatal nutrition, sow's milk, infant formula, porcine uterus, adenogenesis, transcriptomics, microRNA, developmental toxicology, uterine explants, gene expression, reproductive development