This study was performed to investigate whether misoprostol (prostaglandin Fl analogue) (Cytotec, Searle, England) is effective for restoration of bone loss. Four-month-old parous female Sprague-Dawley rats (n = 30) were subjected either to bilateral ovariectomy (OVX, 24 fats) or to sham surgery (sham, 6 rats), The OVX rats were divided into four groups 60 days after the surgery. Six of them were killed, and dual-energy X-ray absorption (Norland xr-36, Norland Corporation, Fort Atkinson, WI, USA) measurements were performed, called pretreatment OVX group. The remaining groups teach had 6 rats) treated orally with 0 (control), 100, 200 mu g/kg/day misoprostol for 60 days. All rats were killed 60 days after having treatment, and bone loss of the lumbar spine was measured by dual-energy X-ray absorption. The bone mineral density was decreased by 25.4% in control group and 23.6% in pretreatment group compared to sham group, but restored by 86% and 96% in groups treated with 100 and 200 mu g/kg/day misoprostol, respectively. These results suggest that misoprostol restores bone loss in the lumbar spine of OVX rats in a dose-dependent manner. (C) 1999 Elsevier Science Inc. All rights reserved.