DEVELOPMENT OF OSTEOPENIA IN OVARIECTOMIZED CYNOMOLGUS MONKEYS (MACACA-FASCICULARIS)

Spinal osteopenia that is due in part to failure to gain bone has prev iously been reported in ovariectomized nonhuman primates. In these stu dies, development of osteopenia over one year was followed by dual-ene rgy x-ray absorptiometry in both domestically-reared and feral ovariec tomized (OVX) and sham-ovariectomized (SHAM) cynomolgus monkeys. To pr omote development of absolute osteopenia, the domestically-reared anim als were all older than nine years and were fed a diet containing 0.14 % calcium for most of the experimental period. Both SHAM and OVX feral animals fed 0.6% calcium gained bone mass, with significantly lower r ates of gain in SHAM monkeys. OVX domestically-reared monkeys lost bon e during one year, while SHAM domestically-reared animals showed no si gnificant change from baseline. Thus, relative osteopenia developed in both experiments, but only the domestically-reared animals developed absolute osteopenia. Nonhuman primates are the only animal model shown to develop absolute osteopenia after ovariectomy. These data suggest that absolute osteopenia develops after ovariectomy in monkeys with st able pre-ovariectomy bone mass which are fed a level of calcium compar able to that consumed by American women.