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Endogenous calcitonin attenuates parathyroid hormone-induced cancellous bone loss in the rat.
Endocrinology 1995; 136(2):788-95E

Abstract

Although calcitonin (CT) treatment has been shown to prevent bone loss in estrogen-deficient states, the function of endogenous CT in bone metabolism is not clearly established. To test the hypothesis that endogenous CT has a role in bone conservation, we compared the bone-resorbing effect of exogenous PTH between CT-deficient [thyroparathyroidectomized (TPTX)] and CT-sufficient [parathyroidectomized (PTX)] rats. Studies were carried out with two doses (30 and 40 pmol/h) of bovine PTH-(1-34) to examine dose responsiveness and with or without T4 replacement in TPTX rats to exclude the influence of thyroid function on the results. Sham-operated control rats received vehicle. At comparable hypercalcemia (mean +/- SEM, 13.6 +/- 0.8 vs. 12.7 +/- 1.0 mg/dl) after 3 days of sc infusion of 30 pmol/h PTH, serum CT levels were significantly (P < 0.05) higher in PTX rats (66.0 +/- 8.0 pg/ml) than in TPTX rats (17.7 +/- 4.3). CT-deficient TPTX rats showed a significant cancellous bone loss in the proximal tibia [bone volume (BV/TV), 4.2 +/- 1.0%] compared with control rats 10.4 +/- 1.2%) In contrast, there was no bone loss in CT-sufficient PTX rats (BV/TV, 10.9 +/- 0.5%). A similar difference in the serum CT level and more marked difference in BV/TV (0.9 +/- 0.3% vs. 8.1 +/- 1.3%) were observed between TPTX and PTX rats infused with 40 pmol/h PTH. The magnitude of bone loss in TPTX rats was not different between T4-supplemented and nonsupplemented groups. Unlike cancellous bone, the PTH-induced decrease in the cortical thickness of the tibia was comparable in TPTX and PTX rats. The extent of increase in serum osteocalcin after PTH infusion was not different between TPTX and PTX groups. These results indicate that in the rat, endogenous CT has a protective effect against PTH-stimulated cancellous bone loss, but not cortical bone loss.

Authors+Show Affiliations

Department of Bone Biology and Osteoporosis Research, Merck Research Laboratories, West Point, Pennsylvania 19486.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

7835311

Citation

Yamamoto, M, et al. "Endogenous Calcitonin Attenuates Parathyroid Hormone-induced Cancellous Bone Loss in the Rat." Endocrinology, vol. 136, no. 2, 1995, pp. 788-95.
Yamamoto M, Seedor JG, Rodan GA, et al. Endogenous calcitonin attenuates parathyroid hormone-induced cancellous bone loss in the rat. Endocrinology. 1995;136(2):788-95.
Yamamoto, M., Seedor, J. G., Rodan, G. A., & Balena, R. (1995). Endogenous calcitonin attenuates parathyroid hormone-induced cancellous bone loss in the rat. Endocrinology, 136(2), pp. 788-95.
Yamamoto M, et al. Endogenous Calcitonin Attenuates Parathyroid Hormone-induced Cancellous Bone Loss in the Rat. Endocrinology. 1995;136(2):788-95. PubMed PMID: 7835311.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Endogenous calcitonin attenuates parathyroid hormone-induced cancellous bone loss in the rat. AU - Yamamoto,M, AU - Seedor,J G, AU - Rodan,G A, AU - Balena,R, PY - 1995/2/1/pubmed PY - 1995/2/1/medline PY - 1995/2/1/entrez SP - 788 EP - 95 JF - Endocrinology JO - Endocrinology VL - 136 IS - 2 N2 - Although calcitonin (CT) treatment has been shown to prevent bone loss in estrogen-deficient states, the function of endogenous CT in bone metabolism is not clearly established. To test the hypothesis that endogenous CT has a role in bone conservation, we compared the bone-resorbing effect of exogenous PTH between CT-deficient [thyroparathyroidectomized (TPTX)] and CT-sufficient [parathyroidectomized (PTX)] rats. Studies were carried out with two doses (30 and 40 pmol/h) of bovine PTH-(1-34) to examine dose responsiveness and with or without T4 replacement in TPTX rats to exclude the influence of thyroid function on the results. Sham-operated control rats received vehicle. At comparable hypercalcemia (mean +/- SEM, 13.6 +/- 0.8 vs. 12.7 +/- 1.0 mg/dl) after 3 days of sc infusion of 30 pmol/h PTH, serum CT levels were significantly (P < 0.05) higher in PTX rats (66.0 +/- 8.0 pg/ml) than in TPTX rats (17.7 +/- 4.3). CT-deficient TPTX rats showed a significant cancellous bone loss in the proximal tibia [bone volume (BV/TV), 4.2 +/- 1.0%] compared with control rats 10.4 +/- 1.2%) In contrast, there was no bone loss in CT-sufficient PTX rats (BV/TV, 10.9 +/- 0.5%). A similar difference in the serum CT level and more marked difference in BV/TV (0.9 +/- 0.3% vs. 8.1 +/- 1.3%) were observed between TPTX and PTX rats infused with 40 pmol/h PTH. The magnitude of bone loss in TPTX rats was not different between T4-supplemented and nonsupplemented groups. Unlike cancellous bone, the PTH-induced decrease in the cortical thickness of the tibia was comparable in TPTX and PTX rats. The extent of increase in serum osteocalcin after PTH infusion was not different between TPTX and PTX groups. These results indicate that in the rat, endogenous CT has a protective effect against PTH-stimulated cancellous bone loss, but not cortical bone loss. SN - 0013-7227 UR - https://www.unboundmedicine.com/medline/citation/7835311/Endogenous_calcitonin_attenuates_parathyroid_hormone_induced_cancellous_bone_loss_in_the_rat_ L2 - https://academic.oup.com/endo/article-lookup/doi/10.1210/endo.136.2.7835311 DB - PRIME DP - Unbound Medicine ER -