Lower serum osteocalcin in ethanol-fed rats

Abstract

Serum osteocalcin was remarkably and significantly (‐34 and −41% in two separate experiments; p < 0.001) lower in rats fed an 8% (w/v) ethanol liquid diet (ELD) for 1 week than in rats fed an isocaloric control liquid diet (CLD). In a longer experiment that spanned 4 weeks, the ELD rats were given 6% ethanol on day 4, increased stepwise to 8% by day 9, and then maintained at 8% until day 28, when the experiment was terminated. Again, serum osteocalcin was much lower (‐32%, p < 0.001) in the ELD‐fed rats than in CLD‐fed rats. Even in rats fed only a 6% ELD for 12 days, serum osteocalcin was lower (‐33%, p < 0.001) than in controls. Also, the femora were weaker, more compliant, and more ductile in ELD‐ than in CLD‐fed rats, findings that confirmed our earlier, related work. The fall in serum osteocalcin in ELD‐fed rats is associated with a fall in femur ash weight and bone strength. There were significant correlations between serum osteocalcin and bone strength (r = 0.80; p < 0.001) and between serum osteocalcin and bone stiffness (r = 0.83; p < 0.001). Serum ionized calcium, like osteocalcin, was consistently lower in rats given ethanol for 1 or 4 weeks than in controls. From these experiments we conclude that excessive ethanol consumption inhibits osteoblastic activity as indicated by the reduced serum osteocalcin. The inhibition is also associated with other deleterious effects of ethanol on bone, including ash weight, bone strength, and bone stiffness. These results in rats suggest that serum osteocalcin may be a useful biologic marker of bone status in alcoholic patients.