Related Experiment Videos
Thyroxine increases epidermal growth factor levels in the mouse thyroid in vivo
S Ozawa1, L G Sheflin, S W Spaulding
1Medical Research Service, Buffalo Veterans Administration Medical Center, New York 14215.
Endocrinology
|March 1, 1991
Summary
Thyroid hormone (T4) influences epidermal growth factor (EGF) levels. T4 increases thyroidal EGF synthesis and decreases plasma EGF, suggesting a feedback mechanism for thyroid function regulation.
Area of Science:
- Endocrinology
- Molecular Biology
- Cell Signaling
Background:
- Immunoreactive epidermal growth factor (EGF) presence in the thyroid raises questions about its origin and regulation.
- Understanding EGF's role in thyroid function is crucial for comprehending thyroid homeostasis.
Purpose of the Study:
- To investigate the effects of manipulating thyroid function on EGF levels in plasma and various tissues.
- To determine the source of thyroidal EGF and its regulation by thyroid hormones.
Main Methods:
- Adult male BALB/c mice were injected with thyroxine (T4) or bovine thyroid-stimulating hormone (TSH).
- Epidermal growth factor (EGF) levels in plasma, thyroid, submaxillary gland, and kidney were measured.
- Prepro-EGF messenger RNA (mRNA) levels were analyzed using reverse transcription and polymerase chain reaction.
Main Results:
- T4 administration significantly decreased plasma EGF levels while increasing thyroidal and submaxillary gland EGF content.
- A strong negative correlation was observed between plasma and thyroidal EGF concentrations.
- Prepro-EGF mRNA was detected in the thyroid, submaxillary gland, and kidney, indicating local synthesis.
Conclusions:
- Thyroidal EGF is likely synthesized within the thyroid gland.
- T4 influences EGF levels in a dose- and time-dependent manner, suggesting a role in thyroid autocrine/paracrine regulation.
- Intrathyroidal EGF may function as a short-loop feedback mechanism for regulating thyroid activity.