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Temporal expression of the anabolic action of PTH in cancellous bone of ovariectomized rats.
J Bone Miner Res. 1996 Apr; 11(4):421-9.JB

Abstract

When administered intermittently, parathyroid hormone (PTH) is a potent anabolic agent in both human and animal bone. To improve our understanding of this anabolic effect, we have examined the time course of PTH action in an established animal model of estrogen deficiency-induced bone loss: the ovariectomized rat. Animals were ovariectomized (Ovx) and allowed to lose bone for 6 weeks. A dose of 20 micrograms/kg/d of rat PTH (1-34) was administered s.c., 6 days each week for periods of 1, 2, 3, 4, 6 and 8 weeks. Animals were sacrificed for evaluation of skeletal histomorphometry of the proximal tibia and mechanical strength of the cancellous bone in the marrow cavity of the distal femur. Cancellous bone volume (Cn-BV/TV) increased gradually over 8 weeks of treatment (16.8 +/- 1.6 to 24.1 +/- 2.7%) as did the bone formation rate (0.308 +/- 0.054 to 1.659 +/- 0.293 microns3/micron2/d), as determined by an increase in both total mineralization surface (15.5 +/- 2.1 to 42.7 +/- 5.0%) and mineral apposition rate (1.88 +/- 0.20 to 3.55 +/- 0.39 microns/d). The largest increments in these variables reflecting bone formation occurred over the first week of treatment. This bone formation was accompanied by an increase in trabecular thickness (Tb.Th) (55.3 +/- 3.4 to 80.5 +/- 5.0 microns) without a corresponding increment in trabecular number (Tb.N) (3.65 +/- 0.17 to 3.55 +/- 0.26). Extensive tetracycline labels were visualized on the surface of trabecular rod-like and plate-like structures. A small transient, though not statistically significant, increase occurred in both eroded surface and urinary pyridinoline concentration immediately after the onset of PTH administration. Osteocalcin showed a small decrement in the first two weeks after PTH administration, but the levels were elevated when compared with the Ovx control in later weeks. Mechanical strength of the cancellous bone also increased significantly with PTH treatment (20.5 +/- 2.4 to 46.1 +/- 10.0 Newtons). Our results showed that: 1) intermittent PTH treatment of Ovx rats elicited an immediate increase of bone formation activity by the existing osteoblasts, 2) the increase of Cn-BV/TV after PTH administration resulted primarily from an increase in Tb.Th, and 3) improved mechanical strength after PTH treatment can be achieved by increases in Tb.Th without an increase in Tb.N.

Authors+Show Affiliations

Regional Bone Center, Helen Hayes Hospital, W. Haverstraw, New York, USA.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Comparative Study
Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

8992872

Citation

Meng, X W., et al. "Temporal Expression of the Anabolic Action of PTH in Cancellous Bone of Ovariectomized Rats." Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, vol. 11, no. 4, 1996, pp. 421-9.
Meng XW, Liang XG, Birchman R, et al. Temporal expression of the anabolic action of PTH in cancellous bone of ovariectomized rats. J Bone Miner Res. 1996;11(4):421-9.
Meng, X. W., Liang, X. G., Birchman, R., Wu, D. D., Dempster, D. W., Lindsay, R., & Shen, V. (1996). Temporal expression of the anabolic action of PTH in cancellous bone of ovariectomized rats. Journal of Bone and Mineral Research : the Official Journal of the American Society for Bone and Mineral Research, 11(4), 421-9.
Meng XW, et al. Temporal Expression of the Anabolic Action of PTH in Cancellous Bone of Ovariectomized Rats. J Bone Miner Res. 1996;11(4):421-9. PubMed PMID: 8992872.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Temporal expression of the anabolic action of PTH in cancellous bone of ovariectomized rats. AU - Meng,X W, AU - Liang,X G, AU - Birchman,R, AU - Wu,D D, AU - Dempster,D W, AU - Lindsay,R, AU - Shen,V, PY - 1996/4/1/pubmed PY - 1996/4/1/medline PY - 1996/4/1/entrez SP - 421 EP - 9 JF - Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research JO - J Bone Miner Res VL - 11 IS - 4 N2 - When administered intermittently, parathyroid hormone (PTH) is a potent anabolic agent in both human and animal bone. To improve our understanding of this anabolic effect, we have examined the time course of PTH action in an established animal model of estrogen deficiency-induced bone loss: the ovariectomized rat. Animals were ovariectomized (Ovx) and allowed to lose bone for 6 weeks. A dose of 20 micrograms/kg/d of rat PTH (1-34) was administered s.c., 6 days each week for periods of 1, 2, 3, 4, 6 and 8 weeks. Animals were sacrificed for evaluation of skeletal histomorphometry of the proximal tibia and mechanical strength of the cancellous bone in the marrow cavity of the distal femur. Cancellous bone volume (Cn-BV/TV) increased gradually over 8 weeks of treatment (16.8 +/- 1.6 to 24.1 +/- 2.7%) as did the bone formation rate (0.308 +/- 0.054 to 1.659 +/- 0.293 microns3/micron2/d), as determined by an increase in both total mineralization surface (15.5 +/- 2.1 to 42.7 +/- 5.0%) and mineral apposition rate (1.88 +/- 0.20 to 3.55 +/- 0.39 microns/d). The largest increments in these variables reflecting bone formation occurred over the first week of treatment. This bone formation was accompanied by an increase in trabecular thickness (Tb.Th) (55.3 +/- 3.4 to 80.5 +/- 5.0 microns) without a corresponding increment in trabecular number (Tb.N) (3.65 +/- 0.17 to 3.55 +/- 0.26). Extensive tetracycline labels were visualized on the surface of trabecular rod-like and plate-like structures. A small transient, though not statistically significant, increase occurred in both eroded surface and urinary pyridinoline concentration immediately after the onset of PTH administration. Osteocalcin showed a small decrement in the first two weeks after PTH administration, but the levels were elevated when compared with the Ovx control in later weeks. Mechanical strength of the cancellous bone also increased significantly with PTH treatment (20.5 +/- 2.4 to 46.1 +/- 10.0 Newtons). Our results showed that: 1) intermittent PTH treatment of Ovx rats elicited an immediate increase of bone formation activity by the existing osteoblasts, 2) the increase of Cn-BV/TV after PTH administration resulted primarily from an increase in Tb.Th, and 3) improved mechanical strength after PTH treatment can be achieved by increases in Tb.Th without an increase in Tb.N. SN - 0884-0431 UR - https://www.unboundmedicine.com/medline/citation/8992872/Temporal_expression_of_the_anabolic_action_of_PTH_in_cancellous_bone_of_ovariectomized_rats_ L2 - https://doi.org/10.1002/jbmr.5650110402 DB - PRIME DP - Unbound Medicine ER -