Adequate thyroid hormone during pregnancy is needed to ensure the normal growth and development of the fetus, and for long term control of carbohydrate metabolism throughout life.

Harris and coworkers used a sheep animal model to examine whether thyroid hormone affects β-cell proliferation in fetal pancreatic islets. Through a series of experiments, they found that hypothyroidism in the fetus has a number of effects on the pancreatic islets. In fetuses whose thyroid gland had been removed, they observed an asymmetric pattern of organ growth, pancreatic β-cell hyperplasia and elevated plasma insulin and leptin levels. When the pancreatic islets were studied in vitro, β-cell proliferation was inhibited by thyroid hormone in a dose-dependent manner, while exposure to insulin and leptin resulted in β-cell proliferation.

This study shows the importance of physiological exposure to appropriate levels of thyroid hormone, insulin and leptin in utero and hints that this may have possible consequences for carbohydrate metabolism later in life.

Read the full article in Journal of Physiology doi:10.1113/JP273555