Pantoprazole, a proton pump inhibitor, does not prevent botulinum toxin induced disuse osteopenia in mice

OBJECTIVES Pantoprazole is a proton pump inhibitor that has been shown to inhibit bone resorption. The aim of the study was to investigate whether pantoprazole can prevent development of botulinum toxin (BTX)-induced disuse osteopenia in mice. METHODS Forty-eight 16-week-old female C57BL/6J mice were randomized into 4 groups (n=12): Base, Ctrl, BTX, and BTX+Pan. The Base group was euthanized at study start. The BTX and BTX+Pan groups were immobilized by injections with BTX in one hind limb. The BTX+Pan group was injected i.p. daily with 100 mg pantoprazole per kg bodyweight. The mice were euthanized after 3 weeks of treatment. The skeletal status was investigated by DEXA, µCT, mechanical testing, dynamic bone histomorphometry, and RT-qPCR. The bone sites investigated were tibia, femur, L5 vertebra, and humerus. RESULTS Injections of BTX induced a pronounced and significant loss of bone density, microstructure, and strength in the immobilized hind limb. Furthermore, the localized intramuscular injections of BTX lead to a slight loss of bone and bone strength at the L5 vertebra and humerus. Treatment with pantoprazole did not have any bone protective or deleterious effects. CONCLUSION Pantoprazole was unable to prevent the development of BTX induced disuse osteopenia in skeletally mature female C57BL/6J mice.