Chronic treatment with angiotensin AT1 receptor antagonists reduced serum but not bone TGF-β1 levels in ovariectomized rats

Approximately 50% of hypertensive patients are postmenopausal women; therefore, any antihypertensive therapy must not adversely affect bone loss in this population. Recently, however, concern has been raised that use of angiotensin AT(1) receptor antagonists may increase the tendency to develop postmenopausal osteoporosis by decreasing transforming growth factor-beta(1) (TGF-beta(1)), which has been implicated in bone mass maintenance. In the present study, we selected telmisartan and valsartan as representatives of angiotensin AT(1) receptor antagonists and used ovariectomized (OVX) rats as a model of human postmenopausal osteoporosis. After 3 months treatment with telmisartan (5 mg/kg daily) or valsartan (10 mg/kg daily), OVX rats showed no signs of adverse effects on bone mineral density of the lumbar vertebrae (L1-L5) or the total femur, nor did treatment affect serum levels of osteocalcin and osteoclast-derived tartrate-resistant acid phosphatase (TRACP-5b). Bone TGF-beta(1) content remained unchanged, although treatment with telmisartan and valsartan significantly reduced serum TGF-beta(1) levels (p < 0.05). In conclusion, chronic treatment with angiotensin AT(1) receptor antagonists reduced serum but not bone TGF-beta(1) levels and did not accelerate ovariectomy-induced bone loss in rats.