Effect of intermittent injection of recombinant human parathyroid hormone on bone histomorphometry of ovariectomized rats.
OBJECTIVE
To observe the effect of intermittent parathyroid hormone (PTH) administration on bone histomorphology of relatively old ovariectomized rats.


METHODS
The 6-month-old female SD rats were randomly divided into 5 groups: (1) sham-operated for baseline (ShamB, n=5), (2)ovariectomized for baseline (OVXB, n=6), (3) Sham-operated for end point (ShamE, n=6), (4) ovariectomized for end point (OVXE, n=6), (5) ovariectomized for PTH treatment (OVXEP, n=6). ShamB and OVXB rats were sacrificed 3 months after operation, ShamE, OVXE and OVXEP rats were sacrificed 4.5 months after operation. During 3-4.5 months after operation, OVXEP rats received daily subcutaneous injection of rhPTH1-84, while ShamE and OVXE received vehicle injection. The proximal tibiae of all rats were processed without decalcification for quantitative bone histomorphometry.


RESULTS
The percent trabecular area (TbAr) of OVXEP was significantly greater than that of OVXE (P <0.05), and was similar to that of OVXB (P >0.05), but was smaller than that of ShamE (P <0.05); the trabecular thickness (TbTh) of OVXEP was thicker than any other group (all, P <0.05); the trabecular number (TbN) of OVXEP was only slightly higher than that of OVXE; the percent labeled perimeter (LPm), mineral apposition rate (MAR) and bone formation rate with bone area as referent (BFR/BV) of OVXEP were all higher than those of ShamE and OVXE respectively (P <0.01), whereas the osteoclast number (N of Oc) of OVXEP was similar to those of ShamE and OVXE (P >0.05).


CONCLUSIONS
Short-term intermittent injection of rhPTH1-84 can prevent further bone loss in 9-month-old rats 3 months after ovariectomy, the mechanisms of this therapy are that PTH could increase TbTh while not alter TbN, and promote bone-forming activity while not influence bone-resorptive activity.
Zhang
Ke-Qin
KQ
Department of Endocrinology, The First Affiliated Hospital of Nanjing Medical University, Nanjing 210029, China. keqzhang@public1.ptt.js.cn
Chen
Jia-Wei
JW
Li
Qing-Nan
QN
Li
Guang-Fu
GF
Tian
Xiao-Yun
XY
Huang
Lian-Fang
LF
Bao
Li-Hua
LH
Wang
Mei-Lian
ML
D000818:Animals; D015519:Bone Density / Q000187:drug effects; D005260:Female; D010012:Osteogenesis / Q000187:drug effects*; D010024:Osteoporosis / Q000473:pathology*; D010052:Ovariectomy; D010281:Parathyroid Hormone / Q000494:pharmacology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D013977:Tibia / Q000187:drug effects / Q000473:pathology
D010281:Parathyroid Hormone; D011994:Recombinant Proteins