Prostaglandin-Induced Resorption of the Adult Rat Calvarium

Prostaglandins are a family of naturally occurring fatty acids that participate in the inflammatory process' 4 and exhibit hormonelike effects.5,6 When prostaglandins are injected intradermally, they produce local inflammatory effects such as increased vascular permeability with edema and vasodilatation with erythema.7,8 They have been identified in inflammatory exudates9-11 and their biosynthesis is inhibited by nonsteroidal anti-inflammatory drugs.12-15 The prostaglandins PGE,, PGE2, and to a lesser extent PGF2a stimulate resorption of cultured fetal rat bones.16'17 In these systems E-type prostaglandins are more potent than is parathyroid hormone in producing bone resorption, although osteolytic action occurs at a slower rate. The action of the E-type prostaglandins and parathyroid hormone is accompanied by elevation of bone cyclic 3'-5' adenosine monophosphate.18 When they are injected systematically, prostaglandins are rapidly metabolized19'20 by 15 dehydrogenation and by reduction of the 13-14 double bond (Fig 1). The biologic activity of the metabolic products is reduced substantially. Because of the rapid inactivation and low