2Molecular Physiology Division, Faculty of Science, Beni-Suef University, 62511 Beni-Suef, Egypt
3Noto Marine Laboratory, Division of Marine Environmental Studies, Institute of Nature and Environmental Technology, Kanazawa University, Noto-Cho, 927-0553 Ishikawa, Japan
* To whom correspondence should be addressed.
Received February 10, 2021; Revised May 27, 2021; Accepted August 6, 2021
Omeprazole suppresses excessive secretion of gastric acid via irreversible inhibition of H+/K+-ATPase in the gastric parietal cells. Recent meta-analysis of data revealed an association between the use of proton pump inhibitors (PPIs) and increased risk of bone fractures, but the underlying molecular mechanism of PPI action remains unclear. In this study, we demonstrated that omeprazole directly influences bone metabolism using a unique in vitro bioassay system with teleost scales, as well as the in vivo model. The in vitro study showed that omeprazole significantly increased the activities of alkaline phosphatase and tartrate-resistant acid phosphatase after 6 h of incubation with this PPI. Expression of mRNAs for several osteoclastic markers was upregulated after 3-h incubation of fish scales with 10−7 M omeprazole. The in vivo experiments revealed that the plasma calcium levels significantly increased in the omeprazole-treated group. The results of in vitro and in vivo studies suggest that omeprazole affects bone cells by increasing bone resorption by upregulating expression of osteoclastic genes and promoting calcium release to the circulation. The suggested in vitro bioassay in fish scales is a practical model that can be used to study the effects of drugs on bone metabolism.
KEY WORDS: omeprazole, fish scales, transcription genes, osteoclastic genes