Lasofoxifene (CP‐336,156) Protects Against the Age‐Related Changes in Bone Mass, Bone Strength, and Total Serum Cholesterol in Intact Aged Male Rats

• Published in: Journal of bone and mineral research 2001-04, Vol.16 (4), p.765-773
• Main Authors: Ke, Hua Zhu, Qi, Hong, Chidsey‐Frink, Kristin L., Crawford, D. Todd, Thompson, David D.
• Format: Article
• Language: English
• Subjects: Adipose Tissue - drug effects; Aging - metabolism; Animals; Biological and medical sciences; body composition; Body Composition - drug effects; Bone and Bones - chemistry; Bone and Bones - drug effects; Bone and Bones - ultrastructure; Bone Density - drug effects; Bone Resorption - prevention & control; Bones, joints and connective tissue. Antiinflammatory agents; Cholesterol - blood; Drug Evaluation, Preclinical; Elasticity - drug effects; Femur - chemistry; Femur - diagnostic imaging; Femur - drug effects; Hypercholesterolemia - prevention & control; lasofoxifene; Lumbar Vertebrae - chemistry; Lumbar Vertebrae - diagnostic imaging; Lumbar Vertebrae - drug effects; Male; male osteoporosis; Medical sciences; Organ Size - drug effects; Osteocalcin - blood; Osteoclasts - drug effects; Osteoporosis - prevention & control; Pharmacology. Drug treatments; Prostate - drug effects; Pyrrolidines - pharmacology; Pyrrolidines - therapeutic use; Rats; Rats, Sprague-Dawley; selective estrogen receptor modulators; Selective Estrogen Receptor Modulators - pharmacology; Selective Estrogen Receptor Modulators - therapeutic use; Stress, Mechanical; Tetrahydronaphthalenes - pharmacology; Tetrahydronaphthalenes - therapeutic use; Tibia - chemistry; Tibia - diagnostic imaging; Tibia - drug effects; Tomography, X-Ray Computed; total serum cholesterol
• ISSN: 0884-0431; 1523-4681
• DOI: 10.1359/jbmr.2001.16.4.765

The purpose of this study was to evaluate if long‐term (6 months) treatment with lasofoxifene (LAS), a new selective estrogen receptor modulator (SERM), can protect against age‐related changes in bone mass and bone strength in intact aged male rats. Sprague‐Dawley male rats at 15 months of age were treated (daily oral gavage) with either vehicle (n = 12) or LAS at 0.01 mg/kg per day (n = 12) or 0.1 mg/kg per day (n = 11) for 6 months. A group of 15 rats was necropsied at 15 months of age and served as basal controls. No significant change was found in body weight between basal and vehicle controls. However, an age‐related increase in fat body mass (+42%) and decrease in lean body mass (−8.5%) was observed in controls. Compared with vehicle controls, LAS at both doses significantly decreased body weight and fat body mass but did not affect lean body mass. No significant difference was found in prostate wet weight among all groups. Total serum cholesterol was significantly decreased in all LAS‐treated rats compared with both the basal and the vehicle controls. Both doses of LAS treatment completely prevented the age‐related increase in serum osteocalcin. Peripheral quantitative computerized tomography (pQCT) analysis at the distal femoral metaphysis indicated that the age‐related decrease in total density, trabecular density, and cortical thickness was completely prevented by treatment with LAS at 0.01 mg/kg per day or 0.1 mg/kg per day. Histomorphometric analysis of proximal tibial cancellous bone showed an age‐related decrease in trabecular bone volume (TBV; −46%), trabecular number (Tb.N), wall thickness (W.Th), mineral apposition rate, and bone formation rate‐tissue area referent. Moreover, an age‐related increase in trabecular separation (Tb.Sp) and eroded surface was observed. LAS at 0.01 mg/kg per day or 0.1 mg/kg per day completely prevented these age‐related changes in bone mass, bone structure, and bone turnover. Similarly, the age‐related decrease in TBV and trabecular thickness (Tb.Th) and the age‐related increase in osteoclast number (Oc.N) and osteoclast surface (Oc.S) in the third lumbar vertebral cancellous bone were completely prevented by treatment with LAS at both doses. Further, LAS at both doses completely prevented the age‐related decrease in ultimate strength (−47%) and stiffness (−37%) of the fifth lumbar vertebral body. These results show that treatment with LAS for 6 months in male rats completely prevents the age‐related decreases