[Dynamic effects of glucocorticoid on bone mineral density and microarchitecture: experiment with rats].
OBJECTIVE
To investigate the Dynamic effects of glucocorticoid (GC) on bone mineral density and microarchitecture time-related changes of trabecular bone in bone mineral density (BMD) and microarchitecture in glucocorticoid-treated rats.


METHODS
Fifty-two 3.5-month-old female SD rats were randomly divided into 3 groups. Ten rats were killed at the beginning of experiment with their right tibiae taken out as the baseline group; 22 rats underwent subcutaneous injection of methylprednisolone once daily (GC-treated group), and the other 20 rats underwent subcutaneous injection of normal saline once daily as control group. One and 9 weeks after the beginning of experiment 11 and 10 rats from GCT Group and control group each were killed with their right tibiae taken out. High resolution micro-CT was used to identify the densitometric and microarchitectural properties of the trabecula in the proximal metaphysic of tibia.


RESULTS
Compared with the control group the values of volumetric BMD (vBMD), tissue BMD (tBMD), bone volume fraction (BVF), trabecular number (Tb.N), degree of anisotropy (DA), and trabecular connectivity (Conn.D) in the trabecular bone at different time-points, of the GCT group all decreased; and the values in the ninth week were the lowest (all P < 0.05). The values of trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), and structure model index (SMI) at different time-points of the GCT group were higher than those of the control group. A time-related analysis within the GCT group showed there was a declination in BVF, Conn.D, Tb.N, and DA with administration time, but Tb.Th and Tb.Sp were increased significantly (all P < 0.05). The mean values of Tb.Th in the first week and the ninth week of GCT Group were (0.076 +/- 0.020) mm and (0.086 +/- 0.026) mm respectively, both higher than the baseline value [(0.067 +/- 0.014) mm] and the values of the control group in the first and ninth weeks [(0.075 +/- 0.022) mm and (0.072 +/- 0.009) mm respectively].


CONCLUSIONS
Administration of GC time dependently decreases the BMD and causes deterioration in microarchitecture of trabecular bone; and the remaining trabeculae seem thicken to increase their strength as compensation.
Liu
Shi-ping
SP
Institute of Metabolism and Endocrinology, Second Xiangya Hospital, Central South University, Changsha 410011, China.
Chen
Jing
J
Yang
Shu-min
SM
Wu
Xian-ping
XP
Liao
Er-yuan
EY
Sheng
Zhi-feng
ZF
Mo
Hui
H
Ma
Yu-lin
YL
Zhang
Yu-hai
YH
Liu
Wei
W
Jin
Yan
Y
Dai
Ru-chun
RC
D000818:Animals; D015519:Bone Density / Q000187:drug effects*; D005260:Female; D005938:Glucocorticoids / Q000008:administration & dosage / Q000494:pharmacology*; D007279:Injections, Subcutaneous; D008775:Methylprednisolone / Q000008:administration & dosage / Q000494:pharmacology; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D013977:Tibia / Q000033:anatomy & histology / Q000187:drug effects* / Q000378:metabolism; D013997:Time Factors
D005938:Glucocorticoids; D008775:Methylprednisolone