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Title: Desensitization of parathyroid hormone receptors on cultured bone cells

Abstract

Administration of excessive amounts of parathyroid hormone (PTH) in the treatment of osteoporosis can reverse the beneficial effects of a low-dose, intermittent regime. To investigate the direct actions and the possible cellular mechanisms of PTH in inducing desensitization of PTH receptors, we studied the effects of desensitization on rat osteoblastic UMR-106 cells. When the osteoblasts were preincubated with bPTH-(1-34), complete refractoriness to a subsequent challenge with the hormone developed within 1 h and at hormone concentrations as low as 5 nM. When osteoblasts thus desensitized were incubated in hormone-free medium, recovery of the cAMP responses began within 2 h and reached maximum after 16 h. Cycloheximide did not affect the process of desensitization. (Nle8,Nle18,Tyr34)bPTH-(3-34)amide significantly impaired the desensitization process by PTH-(1-34) but did not have stimulatory effect on cAMP responses. No significant heterologous desensitization was obvious after preincubation with isoprenaline (50 microM), prostaglandin E1 (50 microM), or prostaglandin E2 (50 microM) for 2 h. Binding experiments with (125I)PLP-(1-36)amide after desensitization revealed that there was an approximate twofold decrease in receptor affinities as analyzed by Scatchard analysis, showing that the decrease in affinity was prominent in the process of desensitization. When the cells were treated with monensin during desensitization, PTH challengemore » after desensitization produced significantly lower cyclic AMP responses. Recovery after desensitization occurred over a period of 16 h. Inclusion of monensin, but not cycloheximide, impaired the recovery. The results show that homologous desensitization of rat osteoblasts to PTH is brought about by the occupancy of receptors by PTH-(1-34) but not by cAMP generation itself.« less

Authors:
; ; ;  [1]
  1. Univ. of Hong Kong (Hong Kong)
Publication Date:
OSTI Identifier:
5962464
Resource Type:
Journal Article
Journal Name:
Journal of Bone and Mineral Research; (USA)
Additional Journal Information:
Journal Volume: 5:12; Journal ID: ISSN 0884-0431
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; PARATHORMONE; RECEPTORS; BIOCHEMICAL REACTION KINETICS; AFFINITY; AMIDES; AMP; BONE CELLS; CELL CULTURES; CYCLOHEXIMIDE; EXPERIMENTAL NEOPLASMS; IODINE 125; OSTEOSARCOMAS; PROSTAGLANDINS; RATS; TUMOR CELLS; ANIMAL CELLS; ANIMALS; ANTI-INFECTIVE AGENTS; ANTIBIOTICS; BETA DECAY RADIOISOTOPES; CONNECTIVE TISSUE CELLS; DAYS LIVING RADIOISOTOPES; DISEASES; DRUGS; ELECTRON CAPTURE RADIOISOTOPES; FUNGICIDES; HORMONES; INTERMEDIATE MASS NUCLEI; IODINE ISOTOPES; ISOTOPES; KINETICS; MAMMALS; MEMBRANE PROTEINS; NEOPLASMS; NUCLEI; NUCLEOTIDES; ODD-EVEN NUCLEI; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; PEPTIDE HORMONES; PESTICIDES; PROTEINS; RADIOISOTOPES; REACTION KINETICS; RODENTS; SARCOMAS; SKELETAL DISEASES; SOMATIC CELLS; VERTEBRATES; 550201* - Biochemistry- Tracer Techniques

Citation Formats

Pun, K K, Ho, P W, Nissenson, R A, and Arnaud, C D. Desensitization of parathyroid hormone receptors on cultured bone cells. United States: N. p., 1990. Web. doi:10.1002/jbmr.5650051202.
Pun, K K, Ho, P W, Nissenson, R A, & Arnaud, C D. Desensitization of parathyroid hormone receptors on cultured bone cells. United States. https://doi.org/10.1002/jbmr.5650051202
Pun, K K, Ho, P W, Nissenson, R A, and Arnaud, C D. 1990. "Desensitization of parathyroid hormone receptors on cultured bone cells". United States. https://doi.org/10.1002/jbmr.5650051202.
@article{osti_5962464,
title = {Desensitization of parathyroid hormone receptors on cultured bone cells},
author = {Pun, K K and Ho, P W and Nissenson, R A and Arnaud, C D},
abstractNote = {Administration of excessive amounts of parathyroid hormone (PTH) in the treatment of osteoporosis can reverse the beneficial effects of a low-dose, intermittent regime. To investigate the direct actions and the possible cellular mechanisms of PTH in inducing desensitization of PTH receptors, we studied the effects of desensitization on rat osteoblastic UMR-106 cells. When the osteoblasts were preincubated with bPTH-(1-34), complete refractoriness to a subsequent challenge with the hormone developed within 1 h and at hormone concentrations as low as 5 nM. When osteoblasts thus desensitized were incubated in hormone-free medium, recovery of the cAMP responses began within 2 h and reached maximum after 16 h. Cycloheximide did not affect the process of desensitization. (Nle8,Nle18,Tyr34)bPTH-(3-34)amide significantly impaired the desensitization process by PTH-(1-34) but did not have stimulatory effect on cAMP responses. No significant heterologous desensitization was obvious after preincubation with isoprenaline (50 microM), prostaglandin E1 (50 microM), or prostaglandin E2 (50 microM) for 2 h. Binding experiments with (125I)PLP-(1-36)amide after desensitization revealed that there was an approximate twofold decrease in receptor affinities as analyzed by Scatchard analysis, showing that the decrease in affinity was prominent in the process of desensitization. When the cells were treated with monensin during desensitization, PTH challenge after desensitization produced significantly lower cyclic AMP responses. Recovery after desensitization occurred over a period of 16 h. Inclusion of monensin, but not cycloheximide, impaired the recovery. The results show that homologous desensitization of rat osteoblasts to PTH is brought about by the occupancy of receptors by PTH-(1-34) but not by cAMP generation itself.},
doi = {10.1002/jbmr.5650051202},
url = {https://www.osti.gov/biblio/5962464}, journal = {Journal of Bone and Mineral Research; (USA)},
issn = {0884-0431},
number = ,
volume = 5:12,
place = {United States},
year = {Sat Dec 01 00:00:00 EST 1990},
month = {Sat Dec 01 00:00:00 EST 1990}
}