Structure of Calvaria after Gastrectomy: An Experimental Study in the Rat

Gastrectomy induces bone loss, suggesting that the stomach is important for calcium homeostasis. In this study we examined the effects of gastrectomy, with or without CaCl2 supplementation, on the structure of the calvaria of the rat.The calvaria were dissected out and transilluminated, and the calvaria thickness was measured before (micrometer) and after fixation and sectioning (microscopy). Sections of the skull were analysed planimetrically for bone tissue area, using computer-assisted image analysis.The time course of the gastrectomy-produced bone loss was studied. After 4 weeks the remaining bone represented about 70% of that in control rats, and after 8 weeks the value was 50%. The thickness of the calvaria was lower in gastrectomized rats than in sham-operated controls. Bone marrow and samples from liver and spleen were examined; no differences were found between experimental and control groups. Daily ingestion of 100 mg CaCl2.2H2O did not prevent the bone loss.It is unlikely that the gastrectomy-produced bone loss reflects calcium deficiency. The results rather support the view that the stomach is important for calcium homeostasis through another mechanism, perhaps involving a hypothetical gastric hormone.