Abstract
Summary Treatment with curcumin attenuated modeled
microgravity-induced bone loss, possibly through abating oxidative
stress and activating vitamin D receptor. Curcumin
might be an effective countermeasure for microgravityinduced
bone loss but remains to be tested in humans.
Introduction Bone loss is one of the most important complications
for human crewmembers who are exposed to longterm
microgravity in space and also for bedridden people.
The aim of the current study was to elucidate whether treatment
with curcumin attenuated bone loss induced by
microgravity.
Methods We used hind-limb suspension (HLS) and rotary
wall vessel bioreactor (RWVB) to model microgravity
in vivo and in vitro, respectively. We investigated the effects
of curcumin consumption (40 mg kg?1 body weight day?1, via
daily oral gavages) on Sprague–Dawley (SD) rats exposed to
HLS for 6 weeks. Then, we investigated the effects of
incubation with curcumin (4 μM) on MC3T3-E1 and
RAW264.7 cells cultured in RWVB.
Results Curcumin alleviated HLS-induced reduction of bone
mineral density in tibiae and preserved bone structure in tibiae
and mechanical strength in femurs. Curcumin alleviated HLSinduced
oxidative stress marked by reduced malondialdehyde
content and increased total sulfhydryl content in femurs. In
cultured MC3T3-E1 cells, curcumin inhibited modeled
microgravity-induced reactive oxygen species (ROS) formation
and enhanced osteoblastic differentiation. In cultured
RAW264.7 cells, curcumin reduced modeled microgravityinduced
ROS formation and attenuated osteoclastogenesis.
In addition, curcumin upregulated vitamin D receptor (VDR)
expression in femurs of rats exposed to HLS and MC3T3-E1
cells exposed to modeled microgravity.
Conclusion Curcumin alleviated HLS-induced bone loss in
rats, possibly via suppressing oxidative stress and upregulating
VDR expression.