STUDY:

JOURNAL: Cell 2003;115:151-162.

AUTHORS: Dr. Mone Zaidi

ABSTRACT: - Despite its name, thyroid-stimulating hormone (TSH) has a number of direct effects on bone cells.

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COMMENTARY: "In medical school, I was taught that TSH regulates thyroid hormone secretion," senior author Dr. Mone Zaidi, from Mount Sinai School of Medicine in New York, said in a statement. "Here, we find that genetic manipulation of TSH receptors has a more profound effect on bone loss than on thyroid function," he added. "This finding was totally unexpected and causes one to wonder if the hormone should be renamed to reflect both its biologic functions."

In the new study, the authors found that TSH directly influenced skeletal remodeling by interacting with TSH receptors on osteoblast and osteoclast precursors. By inhibiting the development of both cell types, TSH worked as a negative regulator of bone formation as well as bone breakdown.

In knockout mice, loss of just 50% of the TSH receptors produced marked osteoporosis combined with focal osteosclerosis, the researchers state. Moreover, this effect occurred even though the animals had normal thyroid hormone levels.

Given the powerful effects that TSH has on bone, Dr. Zaidi said that the current findings should "inspire research into new therapeutics that target bone TSH receptors."