Increased bone resorption precedes bone formation in the ovariectomised rat

This study describes an increase in biochemical and histomorphometric markers of bone resorption prior to increased bone formation and trabecular bone loss in the ovariectomized rat. Six-month-old, female Sprague Dawley rats were either sham operated or ovariectomized (Ovx) and killed at 0, 6, 9, 15, 18, 21, and 42 days postoperation when femora were collected and trabecular bone volume (BV/TV) was determined from von Kossa silver-stained sections using the Quantimet 520 image analysis system in the distal region. A number of these sections were also examined unstained for fluorochrome labels, and stained for acid phosphatase to detect osteoclast-like cells (ACP surface). At 18 days postoperation, lumbar vertebrae were examined. Blood and urine specimens were analyzed for bone-related biochemical variables. ACP surface was significantly greater in Ovx rats compared with sham at 6 days postoperation (mean ACP surface (%TS) +/- SEM: sham 36.4 +/- 1.9; Ovx 40.3 +/- 1.2, P < 0.05) as was urinary hydroxyproline excretion. Serum osteocalcin and alkaline phosphatase activity were not elevated in Ovx rats compared with Sham until 9 days postoperation. Mineral apposition rate (MAR) was increased at 12 days after ovariectomy (mean MAR (microm/day) +/- SEM: sham 0.85 +/- 0.06; Ovx 1.23 +/- 0.06, P < 0.05). Trabecular bone volume (BV/TV) at a specific site in the metaphyseal-diaphyseal core area was significantly lower at 15 days postoperation (mean (%) +/- SEM: Sham 7.40 +/- 1.23, Ovx 4.25 0 0.65, P < 0.05). There was no difference in lumbar vertebral BV/TV between the two groups at 18 days postoperation, however, ACP surface was elevated in the Ovx rats (P < 0.05). A systemic increase in bone resorption at 6 days postovariectomy precedes increased formation whereas the length of time required for the dissolution of trabeculae postoperation is determined locally.N. A. Sims, H. A. Morris, R. J. Moore, T. C. Durbridg

Effect of decalcification on bone mineral content and bending strength of feline femur

10.1007/BF00298748Calcified Tissue International56178-82CTIN

Adrenal Function and Skeletal Regulation

The hormones produced by the adrenal gland have important effects on the bone both in physiological and pathological conditions. The role of cortisol secretion on the bone physiology during growth is not fully understood. During the adult life, the degree of the cortisol secretion, still in the normal range, seems to directly correlate with the bone mineral density in elderly individuals and in osteoporotic women. The overt and subclinical cortisol excess leads to an increased risk of fracture partially independent of the bone mineral density reduction and possibly related to a reduced bone quality. The individual sensitivity to cortisol due to the different polymorphisms of the glucocorticoid receptor (GR) or of the 11\u3b2-hydroxysteroid dehydrogenase may modulate the effect of glucocorticoids (GCs) on the bone, thus explaining, at least in part, the wide interindividual variability of the skeletal consequences of the hypercortisolism. The adrenal androgens excess in congenital adrenal hyperplasia (CAH) importantly affects the bone, leading not only to an early growth acceleration but to a reduction in the final adult height. On the other hand, the reduction of the adrenal androgens during aging has been considered among the pathophysiological mechanisms of the osteoporosis in the elderly, but the effects of the restoration of the androgen levels in the aging-related osteoporosis are conflicting. Finally, the presence of mineralocorticoid receptors has been demonstrated in osteoblast, osteoclast, and osteocyte, and an association exists between indexes of bone strength and some genes involved in aldosterone pathways. In keeping, the condition of hyperaldosteronism has been associated with an increased fracture risk

Professor Barrie Vernon-Roberts, AO, MD, BSc, PhD, FRCPath, FRCPA, FAOrthA (Hon), FRS.SA

This issue of Inflammopharmacology contains papers that have been submitted to commemorate the life and work of Professor Barrie Vernon-Roberts, an outstanding clinical scientist in the field of bone pathology and its pharmacological regulation. This review briefly summarizes his major works and achievements as well as a list of his publications.K. D. Rainsford, D. R. Hayne