Induction of osteoporosis with its influence on osteoporotic determinants and their interrelationships in rats by DEXA.
BACKGROUND
As women are the population most affected by multifactorial osteoporosis, research is focused on unraveling the underlying mechanism of osteoporosis induction in rats by combining ovariectomy (OVX) either with calcium, phosphorus, vitamin C and vitamin D2/D3 deficiency, or by administration of glucocorticoid (dexamethasone).


METHODS
Different skeletal sites of sham, OVX-Diet and OVX-Steroid rats were analyzed by Dual Energy X-ray Absorptiometry (DEXA) at varied time points of 0, 4 and 12 weeks to determine and compare the osteoporotic factors such as bone mineral density (BMD), bone mineral content (BMC), area, body weight and percent fat among different groups and time points. Comparative analysis and interrelationships among osteoporotic determinants by regression analysis were also determined.


RESULTS
T scores were below-2.5 in OVX-Diet rats at 4 and 12 weeks post-OVX. OVX-diet rats revealed pronounced osteoporotic status with reduced BMD and BMC than the steroid counterparts, with the spine and pelvis as the most affected skeletal sites. Increase in percent fat was observed irrespective of the osteoporosis inducers applied. Comparative analysis and interrelationships between osteoporotic determinants that are rarely studied in animals indicate the necessity to analyze BMC and area along with BMD in obtaining meaningful information leading to proper prediction of probability of osteoporotic fractures.


CONCLUSIONS
Enhanced osteoporotic effect observed in OVX-Diet rats indicates that estrogen dysregulation combined with diet treatment induces and enhances osteoporosis with time when compared to the steroid group. Comparative and regression analysis indicates the need to determine BMC along with BMD and area in osteoporotic determination.
Laboratory of Experimental Trauma Surgery, Justus-Liebig University, Giessen, Germany. christian.heiss@chiru.med.uni-giessen.de
Christian
C
Heiss
Parameswari
P
Govindarajan
Gudrun
G
Schlewitz
Nasr Y A
NY
Hemdan
Nathalie
N
Schliefke
Volker
V
Alt
Ulrich
U
Thormann
Katrin Susanne
KS
Lips
Sabine
S
Wenisch
Alexander C
AC
Langheinrich
Daniel
D
Zahner
Reinhard
R
Schnettler
D015502:Absorptiometry, Photon / Q000379:methods*; D050154:Adiposity; D000704:Analysis of Variance; D000818:Animals; D001835:Body Weight; D015519:Bone Density; D001842:Bone and Bones / Q000000981:diagnostic imaging / Q000503:physiopathology; D005260:Female; D010024:Osteoporosis / Q000139:chemically induced* / Q000000981:diagnostic imaging* / Q000473:pathology / Q000503:physiopathology; D051381:Rats; D017207:Rats, Sprague-Dawley