Adult-onset alcohol consumption induces osteopenia in female rats

Background: Alcohol is a known risk factor for osteopenia and fracture in h umans, and its effects on the skeleton have been studied extensively in ani mal models. Almost all studies of rats, however, have begun rats on alcohol diets while the animals were young and still growing. The purpose of the c urrent study was to examine the effects of alcohol consumption on rats that began drinking alcohol as adults, so that the confounding effects of growt h might be minimized. Methods: Nine-month-old female Sprague-Dawley rats were studied for two dur ations (8 and 14 weeks). The following diet groups were used for both durat ions: alcohol (n = 7), in which rats were fed a liquid diet containing etha nol (8.1% v/v; Lieber-DeCarli method); pair-fed (n = 7), in which rats were fed a caloric-equivalent liquid diet matched to the alcohol-fed animals; a nd pellet (n = 6), in which rats consumed standard rat chow and water. A ce ssation protocol was also used in which alcohol- and pair-fed groups were f ed liquid diets for 8 weeks and then given pellet chow and water for 6 week s, with pair feeding maintained during the cessation period. Results: Only minor effects developed in the rats in the 8-week group, but after 14 weeks, the cancellous bone of the proximal tibia was severely oste openic in the alcohol-fed animals. The bone volume and trabecular number we re both significantly lower in the alcohol-fed animals than in the pair-fed and pellet-fed control animals and also lower than in the alcohol-fed anim als in the 8-week group. Mechanical properties of the cancellous bone in th e distal femur also were significantly diminished in the 14-week alcohol-fe d group. Composition and mechanical properties of the cortical bone in the femur diaphysis were largely unaffected, but the yield stress was significa ntly lower in the 14-week alcohol-fed group than in the S-week alcohol-fed group. No significant effects were found in the cessation groups with regar d to almost all parameters measured. Conclusions: Our study results demonstrate that chronic adult-onset alcohol consumption leads to significantly diminished cancellous bone properties a nd that these effects depend on the duration of alcohol use.