Increased bone growth by local prostaglandin E2 in rats

Abstract

The effects of prostaglandin E₂ (PGE₂) on bone growth were investigated in rats. Daily injection of PGE₂ (1, 10, and 100 pmol) was given via local intraosseous route into the metaphysis of the left tibia for 14 days. The contralateral right tibia injected with vehicle and saline was for the control. The rats receiving no injection provided as normal control. The results obtained indicated that PGE₂ slightly but significantly decreased the body weight increment without effect on tibial length. The most prominent effect of PGE₂ was the increase of metaphyseal bone trabeculae by 45–81% in a dose-dependent manner. The microscopic examination revealed that PGE₂ unequivocally increased the new woven bone formation. The bone cell population study showed no difference between the number of osteoblasts and osteoclasts in primary spongiosa of the PGE₂-injected limbs and those of contralateral limbs. However, the numbers of osteoblasts and osteoclasts were markedly increased in secondary spongiosa in the PGE₂-injected limbs. This finding confirmed a stimulatory role of PGE₂ in the bone formation. The local intraosseous injection of PGE₂ was proven to be a good model for the study of local growth factors on bone metabolism with a lower effective dose which eliminates the systemic side effects.