Effect of pharmacological sympathectomy on osteoclastic activity in the gerbilline auditory bulla in vivo

Bone destruction causes hearing loss in various middle ear disorders. The m echanisms of such pathological remodeling are unknown. Unilateral surgical sympathectomy-is known to induce resorption within mandibular and auditory bulla bone. Explanation of the cause of this effect. however, may be confou nded by hemodynamic changes induced by hemicranial sympathectomy and by unc ertainty as to the neuroanatomical origins of sympathetic fibers. In this s tudy, gerbils were infused with guanethidine sulfate (GS) to evaluate the i n vivo effects of systemic sympatholysis on auditory bone remodeling. In ad dition, to discount any direct osteolytic effect, GS was assessed of its bo ne resorbing activity in vitro by means of the calvarial calcium release as say. The in vitro study revealed GS to have no effect on calcium release. T he in vivo study revealed GS to increase both the osteoclast surface and nu mber. Guanethidine-induced sympathectomy has thus been shown to increase re modeling in gerbilline auditory bone, while no direct osteolytic effect cou ld be measured in vitro.