Prenatal exposure to thyroid hormones affects the “biological age” of newborn birds



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Nov. 11 (UPI) – New research suggests that prenatal thyroid hormones affect birds’ “biological age” at birth.

The findings, published Wednesday in the journal Biology Letters, may have implications for aging in humans.

Numerous studies have shown that environmental conditions, such as exposure to maternal stress hormones, can influence the development of the embryo, triggering genetic changes that affect health, aging and lifespan.

One of the ways scientists study cellular aging is by measuring the length of telomeres, the protective ends of chromosomes that protect DNA strands and promote cell replication.

As living organisms age, telomeres shorten, but at a given age, shorter-than-average telomeres can mean an increased risk of disease and mortality.

Studies have previously shown that exposure to maternal stress hormones and other environmental instabilities during embryonic development are associated with shorter telomeres.

For the new study, the researchers used egg injections to expose the embryos of the collared flycatcher to maternal thyroid hormones.

The scientists were surprised to find that the fledglings who experienced prenatal exposure to thyroid hormones were born with longer telomeres than the birds in the control group.

“The telomere biology of humans is closer to the telomere biology of birds than those of traditional laboratory models,” study lead author Antoine Stier said in a news release.

“In both humans and birds, telomere length is minimally invasively measured from small blood samples,” said Stier, a researcher at the University of Turku in Finland.

Since scientists had previously found that prenatal exposure to thyroid hormones was associated with accelerated growth in early childhood, the researchers hypothesized that the embryos exposed from the most recent study had shortened telomeres.

“Based on the natural decline in telomere length observed with age in the same collared flycatcher population, we estimated that chicks hatching from thyroid hormone-injected eggs were about four years younger at birth than hatched chicks. control eggs, ”Turku researcher Suvi Ruuskanen said.

The results suggest that thyroid hormones influence the determination of the biological age of a newborn bird. However, scientists suggest there may be evolutionary costs for this phenomenon.

The researchers also suggest that the findings could have implications for studying aging in humans.

“Considering the interest and controversy surrounding gene therapy studies in humans to elongate telomeres as an anti-aging therapy, this discovery opens up potential avenues to better understand the influence of telomere elongation in animal models,” he said. said Stier.

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