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Epidermal growth factor receptor ontogeny in mice with congenital hypothyroidism
Abstract:
To assess the effect of endogenous thyroid hormone on hepatic EGF receptors in developing mice we measured EGF binding to plasma membrane receptors in liver and brain of mice with congenital hypothyroidism and in euthyroid controls at 20, 30 and 40 days of age. At 20 days hepatic EGF receptor binding was low in both hypothyroid and control animals. Between 20 and 30 days the hepatic binding increased dramatically in the euthyroid animals, an increase that was greater in males than females. The increase in binding was due to an increase in the high affinity receptor population. Among hypothyroid animals there were no changes in hepatic EGF receptor binding with increasing age. In cerebral cortex EGF binding was similar in euthyroid and hypothyroid animals at all ages. These results suggest that thyroxine has regulatory effects on the postnatal ontogeny of hepatic EGF receptors.
Insights
Thyroid hormone significantly impacts the development of hepatic epidermal growth factor (EGF) receptors in mice. Congenital hypothyroidism prevented the normal age-related increase in EGF receptor binding in the liver.
Area of Science:
- Endocrinology
- Developmental Biology
- Molecular Biology
Background:
- Epidermal Growth Factor (EGF) receptors play crucial roles in cellular growth and differentiation.
- Thyroid hormones are essential for normal development and metabolic regulation.
- The specific role of thyroid hormone in the postnatal development of hepatic EGF receptors is not fully understood.
Purpose of the Study:
- To investigate the influence of endogenous thyroid hormone on the ontogeny of hepatic EGF receptors in developing mice.
- To compare EGF receptor binding in the liver and brain of hypothyroid and euthyroid mice during postnatal development.
Main Methods:
- Measurement of EGF binding to liver and brain plasma membrane receptors.
- Comparison of hypothyroid and euthyroid control mice at 20, 30, and 40 days of age.
- Analysis of high-affinity receptor populations.
Main Results:
- Hepatic EGF receptor binding was low at 20 days in both groups.
- Euthyroid mice showed a dramatic increase in hepatic EGF receptor binding between 20 and 30 days, more pronounced in males.
- This increase was attributed to a rise in high-affinity receptors.
- Hypothyroid mice exhibited no age-related changes in hepatic EGF receptor binding.
- Cerebral cortex EGF binding was similar in both groups across all ages.
Conclusions:
- Endogenous thyroid hormone is a key regulator of postnatal development of hepatic EGF receptors.
- Thyroxine deficiency leads to an absence of the normal surge in hepatic EGF receptor binding during early postnatal life.
- Thyroid hormone's effect appears specific to the liver, as brain EGF receptor binding was unaffected.