Risedronate plus prostaglandin E2 is superior to prostaglandin E2 alone in maintaining the added bone after withdrawal in a non-growing bone site in ovariectomized rats

Continuous PGE2 leads to net bone loss while intermittent PGE2 leads to net bone gain in lumbar vertebral bodies of adult female rats

The present study examined the effects of continuous and intermittent PGE2 administration on the cancellous and cortical bone of lumbar vertebral bodies (LVB) in female rats. Six-month-old Sprague-Dawley female rats were divided into 6 groups with 2 control groups and 1 or 3 mg PGE2/kg given either continuously or intermittently for 21 days. Histomorphometric analyses were performed on the cancellous and cortical bone of the fourth and fifth LVBs. Continuous PGE2 exposure led to bone catabolism while intermittent administration led to bone anabolism. Both routes of administration stimulated bone remodeling, but the continuous PGE2 stimulated more than the intermittent route to expose more basic multicellular units (BMUs) to the negative bone balance. The continuous PGE2 caused cancellous bone loss by stimulating bone resorption greater than formation (i.e., negative bone balance) and shortening the formation period. It caused more cortical bone loss than gain, the magnitude of the negative endocortical bone balance and increased intracortical porosity bone loss was greater than for periosteal bone gain. The anabolic effects of intermittent PGE2 resulted from cancellous bone gain by positive bone balance from stimulated bone formation and shortened resorption period; while cortical bone gain occurred from endocortical bone gain exceeding the decrease in periosteal bone and increased intracortical bone loss. Lastly, a scheme to take advantage of the marked PGE2 stimulation of lumbar periosteal apposition in strengthening bone by converting it to an anabolic agent was proposed.

The effect of prostaglandin E(2) (PGE(2)) and long-chain polyunsaturated fatty acids (LC PUFA) on bone formation in piglets: a model for bone growth in nutritional investigation

This research investigates the effects of exogenous prostaglandin E(2) (PGE(2)) treatment and arachidonic acid supplementation on the rate of growth in modelling bone of piglets. The piglet is a good model for the study of infant nutrition and bone growth. PGE(2) and long-chain polyunsaturated fatty acid (LC PUFA) supplementation, alone and in combination, are shown to have little or no effect on cortical bone thickness. Though exogenous PGE(2) supplementation and LC PUFA supplementation may both be effective in promoting bone growth and mass in adults, they do not appear to have the same positive effect on bone growth in infancy over a short term. A dynamic model for bone growth in piglets is proposed here for the first time. This research adds to our knowledge of the relationship between the dynamic histology of bone, the rate of osteogenesis, and the link between nutrition and bone growth.