Effects of ethanol and low-protein diet on bone strontium and its relation with divalent ions' metabolism

Objective: This study was performed in order to analyze the relative and combined effects of ethanol and protein deficiency on bone strontium, and the relation of bone strontium with bone calcium and magnesium, serum osteocalcin and some of the hormones which govern divalent ions metabolism as PTH, corticosterone and testosterone. Methods: Forty adult male Sprague Dawley rats were divided into 4 groups of 10 animals each and fed (following a pair-feeding process) the Lieber-DeCarli liquid rat control diet (18% protein), an isocaloric, 36% ethanol-containing diet, an isocaloric, 2% protein-containing diet and an isocaloric diet containing 2% protein and 36% ethanol, respectively. Eight weeks later, after sacrifice with lethal doses of ketamine, blood was obtained by direct cardiac puncture and centrifuged, in order to determine, by radioimmunoassay, osteocalcin, PTH, testosterone and corticosterone. We also removed the first and second lumbar vertebrae to determine by atomic absorption flame absorptiometry bone content of calcium, magnesium and strontium. Results: Bone strontium was lower in the ethanol-fed animals and higher in the 2% protein-fed animals, only ethanol exerting an independent effect, a negative interaction existing between the 2 factors. Bone strontium was directly related with bone calcium (r = 0.44), and inversely with serum albumin (r = -0.36, p < 0.05). Conclusions: Ethanol and protein deficiency may alter bone strontium content in the Lieber-deCarli rat model.