The rapid degradation of both GIP and GLP-1 by the enzyme dipeptidyl peptidase-4 has led to the development of degradation-resistant GLP-1-receptor agonists and ColonBroom supplement dipeptidyl peptidase-4 inhibitors for the treatment of type 2 diabetes. Diabetes mellitus (DM) is a chronic disease that develops at an alarming rate worldwide (Mohler et al., 2009; Xu et al., 2018). Related complications such as kidney disease, retinopathy, cardiovascular events, neurological disorders, bone loss, and bone fragility would severely reduce the patient’s quality of life (Napoli et al., 2017; Schwartz et al., 2011). DM often leads to the development of osteoporosis, which is one of the serious complications caused by diabetes. Both type T1DM and T2DM are associated with bone abnormalities and increased risk of fractures (Napoli et al., 2017; Schwartz et al., 2011). GLP-1RAs as novel and promising drugs for T2DM, they could stimulate insulin secretion in a glucose-dependent manner, protect β cell function, and suppress glucagon secretion (Lindamood and Taylor, 2015; Aroda, 2018). Currently, GLP-1RAs have been marketed mainly as liraglutide, exendin-4, albiglutide, dulaglutide and semaglutide (Meier, 2012; Sharma et al., 2018). The therapeutic benefit of these drugs in T2DM has raised interest in whether they affect the mechanism of bone metabolism (Mabilleau et al., 2018; Zhang et al., 2018). It has been reported that GLP-1RAs can enhance bone mineral density (BMD), improve bone quality and prevent fractures in diabetic patients and cell and animal experiments further found that GLP-1RAs have excellent potential anti-osteoporosis benefits for postmenopausal osteoporosis, GIOP and senile osteoporosis (Lu et al., 2015; Zhang et al., 2018; Yang et al., 2019; Zhang et al., ColonBroom supplement 2019a; Zhang et al., 2019b). But, the specific role and related mechanisms of GLP-1RAs in the bone metabolism of patients with different types of osteoporosis need to be further explored and clarified.

This review summarizes the current research findings by which GLP-1RAs treatment of osteoporosis and describe possible mechanisms of different types of GLP-1RAs on bone metabolism and osteoporosis. Currently, there is limited scientific research specifically investigating the combined use of AOD peptides with tirzepatide. It enables Singapore enterprises’ research laboratories to gain acceptance for their environmental health and safety data in OECD countries. "Two newer classes of drugs that effectively treat both conditions concurrently represent a huge advance in diabetes care that’s no less significant than the introduction of statins for heart health in 1991. But no study has compared the classes head-to-head to guide patients on which one is better, and in what circumstances. Fxr gene expression was compared with that of β-actin measured on the same sample, in parallel, on the same plate, giving a cycle threshold difference (ΔCT) for Fxr gene minus β-actin. PCR reactions mix consisted of first-strand cDNA template, primers (TaqMan gene expression assays, Applied Biosystems) and PCR Master mix (Applied Biosystems). Scanning clusters and data acquisition were carried out following the manufacturer’s instructions (Agilent, One-colour microarray Gene Expression Analysis). Total RNAs from GLUTag cells, mouse and human epithelial cells were extracted using Extract-All Reagent (Eurobio, Courteboeuf, France) according to the manufacturer’s protocol.

After DNAse treatment (Fermentas, St Rémy Les Chevreuse, France), total RNA (0.5-1 μg) was reverse transcribed using High-Capacity Multiscribe Reverse Transcriptase (Applied Biosystems, St Aubin, France) according to the manufacturer’s protocol. Quantitative PCR with reverse transcription was performed with 7900 HT Fast Real-Time PCR system (Applied Biosystems, Foster City, CA, USA). Total RNAs from FACS-isolated cells were isolated using a micro-scale RNA isolation kit (RNAeasy, Qiagen, Crawley, UK) and were reverse transcribed according to standard protocols using a Peltier Thermal Cycler-225 (MJ Research, Waltham, MA, USA). After three washes in ice-cold PBS, cells were scrapped in ice-cold PBS containing protease inhibitors (1 × , Roche). OCR and ECAR were measured in Seahorse assay buffer containing basic glucose-free DMEM medium (pH 7.4). The following compounds and concentrations were added successively: glucose (10 mmol l−1); oligomycin (1 μmol l−1); 2-deoxyglucose (100 mmol l−1); rotenone (1 μmol l−1) and antimycin A (1 μmol l−1). Measurements of OCR and ECAR in GLUTag cells were performed using the XF24 analyser (Seahorse Bioscience). Cells were centrifuged for 5 min at 3,500g at 4 °C. After centrifugation (5 min at 13,000g at 4 °C) supernatants corresponding to the nuclear fraction were collected.

Supernatants were collected (that is, cytoplasmic fraction) and pellets were lysed in modified RIPA buffer (TRIS HCl pH 7.4 (50 mmol l−1), NaCl (150 mmol l−1), 0.25% DOC, 0.5% NP40, EDTA (1 mmol l−1), 0.1% PIC) 30 min on ice. Microarray analysis. GLUTag cells were treated or not with GW4064 (5 μmol l−1) for 24 h and four RNA samples of each treatment condition were hybridized on mouse GEP 8 × 60 K arrays. Cells were then centrifuged for 1 min at 11,500g at 4 °C. After a pre-clearing step in which protein fractions were incubated with protein A agarose beads (1 h 30 min at 4 °C), cells were centrifuged (5 min at 1,000g at 4 °C) and 200 μg of protein were immunoprecipitated (O/N at 4 °C) with antibody against FXR (2 μg). Beads were resuspended in 2 × migration buffer and heated for 3 min at 100 °C. Laser microirradiation was performed using a PALM (Photo-activated Localization Microscopy, Bernried, Germany) UV-A pulsed solid-state laser (100 Hz, l 1⁄4 355 nm; P.A.L.M. Then immunocomplexes were captured with 100 μl protein A agarose beads 3 h at 4 °C, centrifuged 1 min at 1,000g and washed three times with 800 μl of RIPA modified buffer.