Gastrectomy Causes Bone Loss in the Rat: Is Lack of Gastric Acid Responsible?

Abstract

Total gastrectomy or resection of the acid-producing part of the stomach (fundectomy) in the rat induced a marked and rapid reduction in bone wet weight, ash weight, and density (expressed as ash weight in mg/mm3 bone). Bone volumes were also affected but not as much. The radius, sternum, tibia, and femur were studied. Three weeks after gastrectomy the bone ash weight was reduced by almost 30% and the density by more than 25%. Maximum bone loss (approximately 40%) occurred about 6 weeks after the operation. The bone loss after gastrectomy was somewhat greater than that after fundectomy, whereas antrectomy had a marginal effect only. The percentage trabecular bone volume, calculated from morphometric analysis of histologic sections of the tibia, was greatly reduced by gastrectomy (approximately 50%), somewhat less so by fundectomy, whereas antrectomy had little effect. We set out to study whether calcium malabsorption could explain the bone loss after gastrectomy. Gastric acid is thought to facilitate the intestinal absorption of ingested calcium by mobilizing calcium from insoluble complexes in the diet. The possibility that lack of acid might contribute to the bone loss after gastrectomy was examined in experiments in which the proton pump inhibitor omeprazole was given for 4-8 weeks at such a dose (400 mumol/kg/day) that acid secretion was blocked almost completely during the period of study. This treatment was without effect on bone. However, the possibility could not be excluded that gastrectomized rats develop calcium deficiency for some reason other than lack of acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Pharmacological treatment of osteopenia induced by gastrectomy or ovariectomy in young female rats

“…It may be argued that removal of the acid-producing part of the stomach may cause acidosis and affect calcium/bone metabolism. However, complete inhibition of gastric acid secretion by proton pump inhibitors does not cause osteopenia (Persson et al 1993). The findings support the view that the stomach is important for bone metabolism by mechanisms that are unrelated to dietary deficiencies or lack of gastric acid (see Surve et al 2002).…”

“…Indeed, it seems unlikely that either GX-induced or OVX-induced osteopenia results from generalized nutritional deficiency, as neither the GX rats nor the OVX rats were growth retarded (see Surve et al 2001a, b, Andersson et al 2002. Moreover, a specific deficiency of calcium is unlikely since it has been shown earlier that calcium supplements have no effect (Persson et al 1993, Klinge et al 1995. Vitamin D deficiency is known to cause impaired calcium absorption and osteomalacia.…”

The presence of Helicobacter Pylori in postmenopausal women is not a factor to the decrease of bone mineral density

“…In spite of the importance of gastrectomy-induced osteoporosis, very little is known about the influence of the gastric mucosa on bone metabolism. Since the experimental studies of IVY (15) , who described bone loss in gastrectomized dogs, many studies have demonstrated that the gastric mucosa is related in some way to the incorporation of calcium into bone (19,20,23,31,32,37) . Despite the accepted role of gastric acid secretion in maintaining calcium absorption, the treatment of rats with a potent proton pump inhibitor resulting in almost complete achlorhydria had no effect on bone density, and, in addition, parenteral calcium supplementation did not prevent bone mineral loss in gastrectomized animals (32) .…”

Effect of L-Lactic Acid on the Absorption of Calcium in Gastrectomized Rats.

“…First, gastric acid is thought to dissolve insoluble calcium in the diet, thereby facilitating the absorption of calcium from the small intestine (4-7). Second, hypocalcinocemic gastric peptide hormone, released from the stomach in response to gastrin, is thought to enhance the uptake of calcium into bone (2,8). Third, the rate of delivery of calcium to the small intestine from the stomach is considered a potentially important determinant of calcium absorption (9,10).…”