A hormone with one widely recognized task may not be single purposed after all. Thyroid-stimulating hormone (TSH), which is made in the pituitary gland and circulates in the body, pumps up production of thyroid hormone, an important regulator of metabolism. Now, research demonstrates that TSH also affects the constant remodeling of bone: Lab mice that aren't responsive to TSH show signs of the bone-thinning disease osteoporosis.
Mone Zaidi of Mount Sinai School of Medicine in New York and his colleagues created mice missing half or all copies of the TSH receptor, the cell membrane protein to which the hormone must bind to initiate any of its actions. The mice devoid of TSH receptors were small and sickly and died within 10 weeks.
Mice with half the usual number of TSH receptors appeared healthy but had a hidden problem. Although they made normal amounts of thyroid hormone, these mice had frail bones that were rapidly remodeling themselves–simultaneously destroying