The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation

The endocannabinoid system is expressed in bone, although its role in the regulation of bone growth is controversial. Many studies have examined the effect of endocannabinoids directly on osteoclast function, but few have examined their role in human osteoblast function, which was the aim of the pre...

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Main Authors: Smith, Marie, Wilson, Richard, O’Brien, Sally, Tufarelli, Cristina, Anderson, Susan I., O’Sullivan, Saoirse Elizabeth
Format: Online
Language:English
Published: Public Library of Science 2015
Online Access:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4587563/
id pubmed-4587563
recordtype oai_dc
spelling pubmed-45875632015-10-01 The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation Smith, Marie Wilson, Richard O’Brien, Sally Tufarelli, Cristina Anderson, Susan I. O’Sullivan, Saoirse Elizabeth Research Article The endocannabinoid system is expressed in bone, although its role in the regulation of bone growth is controversial. Many studies have examined the effect of endocannabinoids directly on osteoclast function, but few have examined their role in human osteoblast function, which was the aim of the present study. Human osteoblasts were treated from seeding with increasing concentrations of anandamide or 2-arachidonoylglycerol for between 1 and 21 days. Cell proliferation (DNA content) and differentiation (alkaline phosphatase (ALP), collagen and osteocalcin secretion and calcium deposition) were measured. Anandamide and 2-arachidonoylglycerol significantly decreased osteoblast proliferation after 4 days, associated with a concentration-dependent increase in ALP. Inhibition of endocannabinoid degradation enzymes to increase endocannabinoid tone resulted in similar increases in ALP production. 2-arachidonoylglycerol also decreased osteocalcin secretion. After prolonged (21 day) treatment with 2-arachidonoylglycerol, there was a decrease in collagen content, but no change in calcium deposition. Anandamide did not affect collagen or osteocalcin, but reduced calcium deposition. Anandamide increased levels of phosphorylated CREB, ERK 1/2 and JNK, while 2-arachidonoylglycerol increased phosphorylated CREB and Akt. RT-PCR demonstrated the expression of CB2 and TRPV1, but not CB1 in HOBs. Anandamide-induced changes in HOB differentiation were CB1 and CB2-independent and partially reduced by TRPV1 antagonism, and reduced by inhibition of ERK 1/2 and JNK. Our results have demonstrated a clear involvement of anandamide and 2-arachidonoylglycerol in modulating the activity of human osteoblasts, with anandamide increasing early cell differentiation and 2-AG increasing early, but decreasing late osteoblast-specific markers of differentiation. Public Library of Science 2015-09-28 /pmc/articles/PMC4587563/ /pubmed/26414859 http://dx.doi.org/10.1371/journal.pone.0136546 Text en © 2015 Smith et al http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are properly credited.
repository_type Open Access Journal
institution_category Foreign Institution
institution US National Center for Biotechnology Information
building NCBI PubMed
collection Online Access
language English
format Online
author Smith, Marie
Wilson, Richard
O’Brien, Sally
Tufarelli, Cristina
Anderson, Susan I.
O’Sullivan, Saoirse Elizabeth
spellingShingle Smith, Marie
Wilson, Richard
O’Brien, Sally
Tufarelli, Cristina
Anderson, Susan I.
O’Sullivan, Saoirse Elizabeth
The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation
author_facet Smith, Marie
Wilson, Richard
O’Brien, Sally
Tufarelli, Cristina
Anderson, Susan I.
O’Sullivan, Saoirse Elizabeth
author_sort Smith, Marie
title The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation
title_short The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation
title_full The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation
title_fullStr The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation
title_full_unstemmed The Effects of the Endocannabinoids Anandamide and 2-Arachidonoylglycerol on Human Osteoblast Proliferation and Differentiation
title_sort effects of the endocannabinoids anandamide and 2-arachidonoylglycerol on human osteoblast proliferation and differentiation
description The endocannabinoid system is expressed in bone, although its role in the regulation of bone growth is controversial. Many studies have examined the effect of endocannabinoids directly on osteoclast function, but few have examined their role in human osteoblast function, which was the aim of the present study. Human osteoblasts were treated from seeding with increasing concentrations of anandamide or 2-arachidonoylglycerol for between 1 and 21 days. Cell proliferation (DNA content) and differentiation (alkaline phosphatase (ALP), collagen and osteocalcin secretion and calcium deposition) were measured. Anandamide and 2-arachidonoylglycerol significantly decreased osteoblast proliferation after 4 days, associated with a concentration-dependent increase in ALP. Inhibition of endocannabinoid degradation enzymes to increase endocannabinoid tone resulted in similar increases in ALP production. 2-arachidonoylglycerol also decreased osteocalcin secretion. After prolonged (21 day) treatment with 2-arachidonoylglycerol, there was a decrease in collagen content, but no change in calcium deposition. Anandamide did not affect collagen or osteocalcin, but reduced calcium deposition. Anandamide increased levels of phosphorylated CREB, ERK 1/2 and JNK, while 2-arachidonoylglycerol increased phosphorylated CREB and Akt. RT-PCR demonstrated the expression of CB2 and TRPV1, but not CB1 in HOBs. Anandamide-induced changes in HOB differentiation were CB1 and CB2-independent and partially reduced by TRPV1 antagonism, and reduced by inhibition of ERK 1/2 and JNK. Our results have demonstrated a clear involvement of anandamide and 2-arachidonoylglycerol in modulating the activity of human osteoblasts, with anandamide increasing early cell differentiation and 2-AG increasing early, but decreasing late osteoblast-specific markers of differentiation.
publisher Public Library of Science
publishDate 2015
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4587563/
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