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Keune JA, Wong CP, Branscum AJ, Menn SA, Iwaniec UT, Turner RT. Bone Marrow Adipose Tissue Is Not Required for Reconstitution of the Immune System Following Irradiation in Male Mice. Int J Mol Sci 2024; 25:1980. [PMID: 38396660 PMCID: PMC10889206 DOI: 10.3390/ijms25041980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 01/24/2024] [Accepted: 01/30/2024] [Indexed: 02/25/2024] Open
Abstract
Bone marrow adipose tissue (BMAT) is hypothesized to serve as an expandable/contractible fat depot which functions, in part, to minimize energy requirements for sustaining optimal hematopoiesis. We investigated whether BMAT is required for immune reconstitution following injury. Male wild type (WBB6F1, WT) and BMAT-deficient WBB6F1/J-KitW/KitW-v/J (KitW/W-v) mice were lethally irradiated. Irradiation was followed by adoptive transfer of 1000 purified WT hematopoietic stem cells (HSCs). The extent of immune reconstitution in blood, bone marrow, and lymph nodes in the irradiated mice was determined using HSCs from green fluorescent protein (GFP)-expressing mice. We also evaluated skeletal response to treatment. Detection of GFP-positive B and T cells in peripheral blood at 4 and 9 weeks following adoptive transfer and in bone marrow and lymph nodes following necropsy revealed excellent immune reconstitution in both WT and BMAT-deficient mice. Adipocytes were numerous in the distal femur of WT mice but absent or rare in KitW/W-v mice. Bone parameters, including length, mass, density, bone volume, microarchitecture, and turnover balance, exhibited few differences between WT and BMAT-deficient mice. The minimal differences suggest that BMAT is not required for reconstitution of the immune system following lethal radiation and is not a major contributor to the skeletal phenotypes of kit signaling-deficient mice.
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Affiliation(s)
- Jessica A. Keune
- Skeletal Biology Laboratory, School of Nutrition and Public Health, Oregon State University, Corvallis, OR 97331, USA
| | - Carmen P. Wong
- Skeletal Biology Laboratory, School of Nutrition and Public Health, Oregon State University, Corvallis, OR 97331, USA
| | - Adam J. Branscum
- Biostatistics Program, School of Nutrition and Public Health, Oregon State University, Corvallis, OR 97331, USA
| | - Scott A. Menn
- Radiation Center, Oregon State University, Corvallis, OR 97331, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Nutrition and Public Health, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
| | - Russell T. Turner
- Skeletal Biology Laboratory, School of Nutrition and Public Health, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
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Devine CC, Brown KC, Paton KO, Heveran CM, Martin SA. Rapamycin does not alter bone microarchitecture or material properties quality in young-adult and aged female C57BL/6 mice. JBMR Plus 2024; 8:ziae001. [PMID: 38505525 PMCID: PMC10945714 DOI: 10.1093/jbmrpl/ziae001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 11/13/2023] [Accepted: 11/27/2023] [Indexed: 03/21/2024] Open
Abstract
Advancing age is the strongest risk factor for osteoporosis and skeletal fragility. Rapamycin is an FDA-approved immunosuppressant that inhibits the mechanistic target of rapamycin (mTOR) complex, extends lifespan, and protects against aging-related diseases in multiple species; however, the impact of rapamycin on skeletal tissue is incompletely understood. We evaluated the effects of a short-term, low-dosage, interval rapamycin treatment on bone microarchitecture and strength in young-adult (3 mo old) and aged female (20 mo old) C57BL/6 mice. Rapamycin (2 mg/kg body mass) was administered via intraperitoneal injection 1×/5 d for a duration of 8 wk; this treatment regimen has been shown to induce geroprotective effects while minimizing the side effects associated with higher rapamycin dosages and/or more frequent or prolonged delivery schedules. Aged femurs exhibited lower cancellous bone mineral density, volume, trabecular connectivity density and number, higher trabecular thickness and spacing, and lower cortical thickness compared to young-adult mice. Rapamycin had no impact on assessed microCT parameters. Flexural testing of the femur revealed that both yield strength and ultimate strength were lower in aged mice compared to young-adult mice. There were no effects of rapamycin on these or other measures of bone biomechanics. Age, but not rapamycin, altered local and global measures of bone turnover. These data demonstrate that short-term, low-dosage interval rapamycin treatment does not negatively or positively impact the skeleton of young-adult and aged mice.
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Affiliation(s)
- Connor C Devine
- Chemical and Biological Engineering Department, Montana State University, Bozeman, MT 59718, United States
| | - Kenna C Brown
- Mechanical and Industrial Engineering Department, Montana State University, Bozeman, MT 59718, United States
| | - Kat O Paton
- Translational Biomarkers Core Laboratory, Center for American Indian and Rural Health Equity, Montana State University, Bozeman, MT 59718, United States
- Biology of Aging Laboratory, Center for American Indian and Rural Health Equity, Montana State University, Bozeman, MT 59718, United States
| | - Chelsea M Heveran
- Mechanical and Industrial Engineering Department, Montana State University, Bozeman, MT 59718, United States
| | - Stephen A Martin
- Translational Biomarkers Core Laboratory, Center for American Indian and Rural Health Equity, Montana State University, Bozeman, MT 59718, United States
- Biology of Aging Laboratory, Center for American Indian and Rural Health Equity, Montana State University, Bozeman, MT 59718, United States
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Wong CP, Iwaniec UT, Turner RT. Brown adipose tissue but not tibia exhibits a dramatic response to acute reduction in environmental temperature in growing male mice. Bone Rep 2023; 19:101706. [PMID: 37637756 PMCID: PMC10448410 DOI: 10.1016/j.bonr.2023.101706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2023] [Revised: 08/04/2023] [Accepted: 08/07/2023] [Indexed: 08/29/2023] Open
Abstract
Mice are typically housed at room temperature (∼22 °C), which is well below their thermoneutral zone and results in cold stress. Chronic cold stress leads to increased adaptive thermogenesis and reductions in cancellous bone volume and bone marrow adipose tissue mass in long bones of growing mice. There is strong evidence that increased neuronal activity initiates the metabolic response of intrascapular brown adipose tissue (BAT) to cold stress, but it is less clear whether bone is regulated through a similar mechanism. Therefore, we compared the short-term response of BAT and whole tibia to a reduction in environmental temperature. To accomplish this, we transferred a group of 6-week-old male mice from 32 °C to 22 °C housing and sacrificed the mice 24 h later. Age-matched controls were maintained at 32 °C. We then evaluated expression levels of a panel of genes related to adipocyte differentiation and fat metabolism in BAT and tibia, and a panel of genes related to bone metabolism in tibia. The decrease in housing temperature resulted in changes in expression levels for 47/86 genes related to adipocyte differentiation and fat metabolism in BAT, including 9-fold and 17-fold increases in Ucp1 and Dio2, respectively. In contrast, only 1/86 genes related to adipocyte differentiation and fat metabolism and 4/84 genes related to bone metabolism were differentially expressed in tibia. These findings suggest that bone, although innervated with sensory and sympathetic neurons, does not respond as rapidly as BAT to changes in environmental temperature.
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Affiliation(s)
- Carmen P. Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
| | - Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
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4
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Beaver LM, Prati M, Gilman KE, Luo T, Shay NF, Branscum AJ, Turner RT, Iwaniec UT. Diet composition influences the effect of high fat diets on bone in growing male mice. Bone 2023; 176:116888. [PMID: 37652285 DOI: 10.1016/j.bone.2023.116888] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/28/2023] [Revised: 08/26/2023] [Accepted: 08/28/2023] [Indexed: 09/02/2023]
Abstract
The effect of diet-induced obesity on bone in rodents is variable, with bone mass increases, decreases, and no impact reported. The goal of this study was to evaluate whether the composition of obesogenic diet may influence bone independent of its effect on body weight. As proof-of-principle, we used a mouse model to compare the skeletal effects of a commonly used high fat 'Western' diet and a modified high fat diet. The modified high fat diet included ground English walnut and was isocaloric for macronutrients, but differed in fatty acid composition and contained nutrients (e.g. polyphenols) not present in the standard 'Western' diet. Eight-week-old mice were randomized into 1 of 3 dietary treatments (n = 8/group): (1) low fat control diet (LF; 10 % kcal fat); (2) high fat 'Western' diet (HF; 46 % kcal fat as soybean oil and lard); or (3) modified high fat diet supplemented with ground walnuts (HF + walnut; 46 % kcal fat as soybean oil, lard, and walnut) and maintained on their respective diets for 9 weeks. Bone response in femur was then evaluated using dual energy x-ray absorptiometry, microcomputed tomography, and histomorphometry. Consumption of both obesogenic diets resulted in increased weight gain but differed in impact on bone and bone marrow adiposity in distal femur metaphysis. Mice consuming the high fat 'Western' diet exhibited a tendency for lower cancellous bone volume fraction and connectivity density, and had lower osteoblast-lined bone perimeter (an index of bone formation) and higher bone marrow adiposity than low fat controls. Mice fed the modified high fat diet did not differ from mice fed control (low fat) diet in cancellous bone microarchitecture, or osteoblast-lined bone perimeter, and exhibited lower bone marrow adiposity compared to mice fed the 'Western' diet. This proof-of-principal study demonstrates that two obesogenic diets, similar in macronutrient distribution and induction of weight gain, can have different effects on cancellous bone in distal femur metaphysis. Because the composition of the diets used to induce obesity in rodents does not recapitulate a common human diet, our finding challenges the translatability of rodent studies evaluating the impact of diet-induced obesity on bone.
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Affiliation(s)
- Laura M Beaver
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA; Linus Pauling Institute, Oregon State University, Corvallis, OR, USA
| | - Maud Prati
- Food Science and Technology, Oregon State University, Corvallis, OR, USA
| | - Kristy E Gilman
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Ting Luo
- Food Science and Technology, Oregon State University, Corvallis, OR, USA
| | - Neil F Shay
- Food Science and Technology, Oregon State University, Corvallis, OR, USA
| | - Adam J Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA
| | - Russell T Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA; Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA
| | - Urszula T Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, USA; Center for Healthy Aging Research, Oregon State University, Corvallis, OR, USA.
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Langlais AL, Mountain RV, Kunst RF, Barlow D, Houseknecht KL, Motyl KJ. Thermoneutral housing does not rescue olanzapine-induced trabecular bone loss in C57BL/6J female mice. Biochimie 2023; 210:50-60. [PMID: 37236340 PMCID: PMC10357956 DOI: 10.1016/j.biochi.2023.05.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 04/27/2023] [Accepted: 05/03/2023] [Indexed: 05/28/2023]
Abstract
Antipsychotic drugs are prescribed to a wide range of individuals to treat mental health conditions including schizophrenia. However, antipsychotic drugs cause bone loss and increase fracture risk. We previously found that the atypical antipsychotic (AA) drug risperidone causes bone loss through multiple pharmacological mechanisms, including activation of the sympathetic nervous system in mice treated with clinically relevant doses. However, bone loss was dependent upon housing temperature, which modulates sympathetic activity. Another AA drug, olanzapine, has substantial metabolic side effects, including weight gain and insulin resistance, but it is unknown whether bone and metabolic outcomes of olanzapine are also dependent upon housing temperature in mice. We therefore treated eight week-old female mice with vehicle or olanzapine for four weeks, housed at either room temperature (23 °C) or thermoneutrality (28-30 °C), which has previously been shown to be positive for bone. Olanzapine caused significant trabecular bone loss (-13% BV/TV), likely through increased RANKL-dependent osteoclast resorption, which was not suppressed by thermoneutral housing. Additionally, olanzapine inhibited cortical bone expansion at thermoneutrality, but did not alter cortical bone expansion at room temperature. Olanzapine also increased markers of thermogenesis within brown and inguinal adipose depots independent of housing temperature. Overall, olanzapine causes trabecular bone loss and inhibits the positive effect of thermoneutral housing on bone. Understanding how housing temperature modulates the impact of AA drugs on bone is important for future pre-clinical studies, as well as for the prescription of AA drugs, particularly to older adults and adolescents who are most vulnerable to the effects on bone.
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Affiliation(s)
- Audrie L Langlais
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA; Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA
| | - Rebecca V Mountain
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA
| | - Roni F Kunst
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA
| | - Deborah Barlow
- Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, ME, USA
| | - Karen L Houseknecht
- Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA; Department of Biomedical Sciences, College of Osteopathic Medicine, University of New England, Biddeford, ME, USA
| | - Katherine J Motyl
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA; Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA; Tufts University School of Medicine, Tufts University, Boston, MA, USA.
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Sattgast LH, Wong CP, Branscum AJ, Olson DA, Aguirre-Burk AM, Iwaniec UT, Turner RT. Small changes in thermoregulation influence cancellous bone turnover balance in distal femur metaphysis in growing female mice. Bone Rep 2023; 18:101675. [PMID: 37007217 PMCID: PMC10063413 DOI: 10.1016/j.bonr.2023.101675] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/16/2023] [Accepted: 03/18/2023] [Indexed: 03/30/2023] Open
Abstract
Mice are typically housed at temperatures well below their thermoneutral zone. When individually housed at room temperature (~22 °C) mice experience cold stress which results in cancellous bone loss and has the potential to alter the skeletal response to treatment. It is not clear if there is a threshold temperature for cold stress-induced bone loss. It is also not clear if alternative strategies for attenuating cold stress, such as group housing, influence bone accrual and turnover. This study aimed to determine how small differences in temperature (4 °C) or heat loss (individual versus group housing with nestlets) influence bone in growing female C57BL/6 J mice. Five-week-old mice were randomized by weight to 1 of 4 treatment groups (N = 10/group): 1) baseline, 2) single housed at 22 °C, 3) single housed at 26 °C, or 4) group housed (n = 5/cage) with nestlets at 22 °C. Mice in the baseline group were sacrificed 1 week later, at 6 weeks of age. The other 3 groups of mice were maintained at their respective temperatures and housing conditions for 13 weeks until 18 weeks of age. Compared to baseline, mice single housed at room temperature had increased body weight and femur size, but dramatically decreased cancellous bone volume fraction in distal femur metaphysis. The cancellous bone loss was attenuated but not prevented in mice individually housed at 26 °C or group housed at 22 °C. In conclusion, by impacting thermogenesis or heat loss, modest differences in housing conditions could influence experimental results.
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Affiliation(s)
- Lara H. Sattgast
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Carmen P. Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Dawn A. Olson
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Allan M. Aguirre-Burk
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
| | - Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR 97331, USA
- Corresponding author at: Skeletal Biology Laboratory, School of Biological and Population Health Sciences, 127 Milam Hall, Oregon State University, Corvallis, OR 97331, USA.
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Mountain RV, Langlais AL, Hu D, Baron R, Lary CW, Motyl KJ. Social isolation through single housing negatively affects trabecular and cortical bone in adult male, but not female, C57BL/6J mice. Bone 2023; 172:116762. [PMID: 37044360 PMCID: PMC10084633 DOI: 10.1016/j.bone.2023.116762] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/30/2023] [Accepted: 04/05/2023] [Indexed: 04/14/2023]
Abstract
Social isolation is a potent form of psychosocial stress and is a growing public health concern, particularly among older adults. Even prior to the onset of the COVID-19 pandemic, which has significantly increased the prevalence of isolation and loneliness, researchers have been concerned about a rising "epidemic" of loneliness. Isolation is associated with an increased risk for many physical and mental health disorders and increased overall mortality risk. In addition to social isolation, older adults are also at greater risk for osteoporosis and related fractures. While researchers have investigated the negative effects of other forms of psychosocial stress on bone, including depression and PTSD, the effects of social isolation on bone have not been thoroughly investigated. The aim of this study was to test the hypothesis that social isolation would lead to bone loss in male and female C57BL/6J mice. 16-week-old mice were randomized into social isolation (1 mouse/cage) or grouped housing (4 mice/cage) for four weeks. Social isolation significantly decreased trabecular (BV/TV, BMD, Tb. N., Tb. Th.) and cortical bone (Ct.Th., Ct.Ar., Ct.Ar./Tt.Ar., pMOI, Ct.Por.) parameters in male, but not female mice. Isolated male mice had signs of reduced bone remodeling represented by reduced osteoblast numbers, osteoblast-related gene expression and osteoclast-related gene expression. However, isolated females had increased bone resorption-related gene expression, without any change in bone mass. Overall, our data suggest that social isolation has negative effects on bone in male, but not female mice, although females showed suggestive effects on bone resorption. These results provide critical insight into the effects of isolation on bone and have key clinical implications as we grapple with the long-term health impacts of the rise in social isolation related to the COVID-19 pandemic.
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Affiliation(s)
- Rebecca V Mountain
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA.
| | - Audrie L Langlais
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA; Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA
| | - Dorothy Hu
- Department of Medicine, Harvard Medical School, Boston, MA, USA; Division of Bone and Mineral Research, Harvard School of Dental Medicine, Boston, MA, USA; Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
| | - Roland Baron
- Department of Medicine, Harvard Medical School, Boston, MA, USA; Division of Bone and Mineral Research, Harvard School of Dental Medicine, Boston, MA, USA; Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
| | - Christine W Lary
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA; Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA; Roux Institute, Northeastern University, Portland, ME, USA
| | - Katherine J Motyl
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA; Graduate School of Biomedical Science and Engineering, University of Maine, Orono, ME, USA; Tufts University School of Medicine, Tufts University, Boston, MA, USA
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8
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Peurière L, Mastrandrea C, Vanden-Bossche A, Linossier MT, Thomas M, Normand M, Lafage-Proust MH, Vico L. Hindlimb unloading in C57BL/6J mice induces bone loss at thermoneutrality without change in osteocyte and lacuno-canalicular network. Bone 2023; 169:116640. [PMID: 36526262 DOI: 10.1016/j.bone.2022.116640] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Revised: 11/13/2022] [Accepted: 11/30/2022] [Indexed: 12/15/2022]
Abstract
Impaired mechanical stimuli during hindlimb unloading (HLU) are believed to exacerbate osteocyte paracrine regulation of osteoclasts. We hypothesized that bone loss and deterioration of the osteocyte lacuno-canalicular network are attenuated in HLU mice housed at thermoneutrality (28 °C) compared with those housed at ambient temperature (22 °C). Following acclimatization, 20-week-old male C57BL/6J mice were submitted to HLU or kept in pair-fed control cages (CONT), for 5 days (5d) or 14d, at 22 °C or 28 °C. In the femur distal metaphysis, thermoneutral CONT mice had higher bone volume (p = 0.0007, BV/TV, in vivo μCT, vs. 14dCONT22) whilst osteoclastic surfaces of CONT and HLU were greater at 22 °C (5dCONT22 + 53 %, 5dHLU22 + 50 %, 14dCONT22 + 186 %, 14dHLU22 + 104 %, vs matching 28 °C group). In the femur diaphysis and at both temperatures, 14dHLU exhibited thinner cortices distally or proximally compared to controls; the mid-diaphysis being thicker at 28 °C than at 22 °C in all groups. Expression of cortical genes for proteolytic enzyme (Mmp13), markers for osteoclastogenic differentiation (MCSF, RANKL), and activity (TRAP, Ctsk) were increased following 22 °C HLU, whereas only Ctsk expression was increased following 28 °C HLU. Expression of cortical genes for apoptosis, senescence, and autophagy were not elevated following HLU at any temperature. Osteocyte density at the posterior mid-diaphysis was similar between groups, as was the proportion of empty lacunae (<0.5 %). However, analysis of the lacuno-canalicular network (LCN, fluorescein staining) revealed unstained areas in the 14dHLU22 group only, suggesting disrupted LCN flow in this group alone. In conclusion, 28 °C housing influences the HLU bone response but does not prevent bone loss. Furthermore, our results do not show osteocyte senescence or death, and at thermoneutrality, HLU-induced bone resorption is not triggered by osteoclastic activators RANKL and MCSF.
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Affiliation(s)
- Laura Peurière
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France.
| | - Carmelo Mastrandrea
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Arnaud Vanden-Bossche
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Marie-Thérèse Linossier
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Mireille Thomas
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Myriam Normand
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Marie-Hélène Lafage-Proust
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
| | - Laurence Vico
- Université Jean Monnet Saint-Étienne, Mines Saint-Étienne, INSERM, SAINBIOSE U1059, F-42023, Saint-Étienne, France
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9
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Jacobson A, Tastad CA, Creecy A, Wallace JM. Combined Thermoneutral Housing and Raloxifene Treatment Improves Trabecular Bone Microarchitecture and Strength in Growing Female Mice. Calcif Tissue Int 2023; 112:359-362. [PMID: 36371724 PMCID: PMC10942733 DOI: 10.1007/s00223-022-01038-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 10/26/2022] [Indexed: 11/15/2022]
Abstract
Thermoneutral housing and Raloxifene (RAL) treatment both have potential for improving mechanical and architectural properties of bone. Housing mice within a 30 to 32 °C range improves bone quality by reducing the consequences of cold stress, such as shivering and metabolic energy consumption (Chevalier et al. in Cell Metab 32(4):575-590.e7, 2020; Martin et al. in Endocr Connect 8(11):1455-1467, 2019; Hankenson et al. in Comp Med 68(6):425-438, 2018). Previous work suggests that Raloxifene can enhance bone strength and geometry (Ettinger et al. in Jama 282(7):637-645, 1999; Powell et al. in Bone Rep 12:100246, 2020). An earlier study in our lab utilized long bones to examine the effect of thermoneutral housing and Raloxifene treatment in mice, but no significant interactive effects were found. The lack of an impact is hypothesized to be connected to the short 6-week duration of the study and the type of bone analyzed. This study will examine the same question within the axial skeleton, which has a higher proportion of trabecular bone. After 6 weeks of treatment with RAL, vertebrae from female C57BL/6 J mice underwent microcomputed tomography (μCT), architectural analysis, and compression testing. Most of the tested geometric properties (bone volume/tissue volume percent, trabecular thickness, trabecular number, trabecular spacing) improved with both the housing and RAL treatment. The effect sizes suggested an additive effect when treating mice housed under thermoneutral conditions. While ultimate force was enhanced with the treatment and housing, force normalized by bone volume fraction was not significantly different between groups. For longer pre-clinical trials, it may be important to consider the impacts of temperature on mice to improve the accuracy of these models.
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Affiliation(s)
- Andrea Jacobson
- Department of Biomedical Engineering, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA
| | - Carli A Tastad
- Department of Biomedical Engineering, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA
| | - Amy Creecy
- Department of Biomedical Engineering, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA
| | - Joseph M Wallace
- Department of Biomedical Engineering, Indiana University - Purdue University Indianapolis, Indianapolis, IN, USA.
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10
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Mountain RV, Langlais AL, Hu D, Baron R, Lary CW, Motyl KJ. Social Isolation Causes Cortical and Trabecular Bone Loss in Adult Male, but not Female, C57BL/6J Mice. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.27.525939. [PMID: 36747686 PMCID: PMC9900878 DOI: 10.1101/2023.01.27.525939] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Social isolation is a potent form of psychosocial stress and is a growing public health concern, particularly among older adults. Even prior to the onset of the COVID-19 pandemic, which has significantly increased the prevalence of isolation and loneliness, researchers have been concerned about a rising "epidemic" of loneliness. Isolation is associated with an increased risk for many physical and mental health disorders and increased overall mortality risk. In addition to social isolation, older adults are also at greater risk for osteoporosis and related fractures. While researchers have investigated the negative effects of other forms of psychosocial stress on bone, including depression and PTSD, the effects of social isolation on bone have not been thoroughly investigated. The aim of this study was to test the hypothesis that social isolation would lead to bone loss in male and female C57BL/6J mice. 16-week-old mice were randomized into social isolation (1 mouse/cage) or grouped housing (4 mice/cage) for four weeks (N=16/group). Social isolation significantly decreased trabecular (BV/TV, BMD, Tb. N., Tb. Th.) and cortical bone (Ct.Th., Ct.Ar., Ct.Ar./Tt.Ar., pMOI, Ct.Por.) parameters in male, but not female mice. Isolated male mice had signs of reduced bone remodeling represented by reduced osteoblast numbers, osteoblast-related gene expression and osteoclast-related gene expression. However, isolated females had increased bone resorption-related gene expression, without any change in bone mass. Overall, our data suggest that social isolation has negative effects on bone in males, but not females, although females showed suggestive effects on bone resorption. These results provide critical insight into the effects of isolation on bone and have key clinical implications as we grapple with the long-term health impacts of the rise in social isolation related to the COVID-19 pandemic.
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Affiliation(s)
- Rebecca V. Mountain
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA
| | - Audrie L. Langlais
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA.,Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, USA
| | - Dorothy Hu
- Department of Medicine, Harvard Medical School, and Division of Bone and Mineral Research, and Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
| | - Roland Baron
- Department of Medicine, Harvard Medical School, and Division of Bone and Mineral Research, and Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA, USA
| | - Christine W. Lary
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA.,Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, USA.,Roux Institute, Northeastern University, Portland, ME, USA
| | - Katherine J. Motyl
- Center for Molecular Medicine, MaineHealth Institute for Research, MaineHealth, Scarborough, ME, USA.,Graduate School of Biomedical Sciences and Engineering, University of Maine, Orono, ME, USA.,Tufts University School of Medicine, Tufts University, Boston, MA, USA
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11
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Wong CP, Branscum AJ, Fichter AR, Sargent J, Iwaniec UT, Turner RT. Cold stress during room temperature housing alters skeletal response to simulated microgravity (hindlimb unloading) in growing female C57BL6 mice. Biochimie 2022:S0300-9084(22)00333-9. [PMID: 36584865 DOI: 10.1016/j.biochi.2022.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Revised: 11/29/2022] [Accepted: 12/14/2022] [Indexed: 12/29/2022]
Abstract
Laboratory mice are typically housed at temperatures below the thermoneutral zone for the species, resulting in cold stress and premature cancellous bone loss. Furthermore, mice are more dependent upon non-shivering thermogenesis to maintain body temperature during spaceflight, suggesting that microgravity-induced bone loss may be due, in part, to altered thermogenesis. Consequently, we assessed whether housing mice at room temperature modifies the skeletal response to simulated microgravity. This possibility was tested using the hindlimb unloading (HLU) model to mechanically unload femora. Humeri were also assessed as they remain weight bearing during HLU. Six-week-old female C57BL6 (B6) mice were housed at room temperature (22 °C) or near thermoneutral (32 °C) and HLU for 2 weeks. Compared to baseline, HLU resulted in cortical bone loss in femur, but the magnitude of reduction was greater in mice housed at 22 °C. Cancellous osteopenia in distal femur (metaphysis and epiphysis) was noted in HLU mice housed at both temperatures. However, bone loss occurred at 22 °C, whereas the bone deficit at 32 °C was due to failure to accrue bone. HLU resulted in cortical and cancellous bone deficits (compared to baseline) in humeri of mice housed at 22 °C. In contrast, fewer osteopenic changes were detected in mice housed at 32 °C. These findings support the hypothesis that environmental temperature alters the skeletal response to HLU in growing female mice in a bone compartment-specific manner. Taken together, species differences in thermoregulation should be taken into consideration when interpreting the skeletal response to simulated microgravity.
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Affiliation(s)
- Carmen P Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Adam J Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Aidan R Fichter
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA
| | - Jennifer Sargent
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, 97331 USA
| | - Urszula T Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA; Center for Healthy Aging Research, Oregon State University, Corvallis, OR, 97331, USA
| | - Russell T Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, 97331, USA; Center for Healthy Aging Research, Oregon State University, Corvallis, OR, 97331, USA.
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12
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Welhaven HD, Vahidi G, Walk ST, Bothner B, Martin SA, Heveran CM, June RK. The cortical bone metabolome of
C57BL
/
6J
mice is sexually dimorphic. JBMR Plus 2022; 6:e10654. [PMID: 35866150 PMCID: PMC9289981 DOI: 10.1002/jbm4.10654] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/11/2022] [Revised: 05/05/2022] [Accepted: 05/23/2022] [Indexed: 11/13/2022] Open
Abstract
Cortical bone quality, which is sexually dimorphic, depends on bone turnover and therefore on the activities of remodeling bone cells. However, sex differences in cortical bone metabolism are not yet defined. Adding to the uncertainty about cortical bone metabolism, the metabolomes of whole bone, isolated cortical bone without marrow, and bone marrow have not been compared. We hypothesized that the metabolome of isolated cortical bone would be distinct from that of bone marrow and would reveal sex differences. Metabolite profiles from liquid chromatography–mass spectrometry (LC‐MS) of whole bone, isolated cortical bone, and bone marrow were generated from humeri from 20‐week‐old female C57Bl/6J mice. The cortical bone metabolomes were then compared for 20‐week‐old female and male C57Bl/6J mice. Femurs from male and female mice were evaluated for flexural material properties and were then categorized into bone strength groups. The metabolome of isolated cortical bone was distinct from both whole bone and bone marrow. We also found sex differences in the isolated cortical bone metabolome. Based on metabolite pathway analysis, females had higher lipid metabolism, and males had higher amino acid metabolism. High‐strength bones, regardless of sex, had greater tryptophan and purine metabolism. For males, high‐strength bones had upregulated nucleotide metabolism, whereas lower‐strength bones had greater pentose phosphate pathway metabolism. Because the higher‐strength groups (females compared with males, high‐strength males compared with lower‐strength males) had higher serum type I collagen cross‐linked C‐telopeptide (CTX1)/procollagen type 1 N propeptide (P1NP), we estimate that the metabolomic signature of bone strength in our study at least partially reflects differences in bone turnover. These data provide novel insight into bone bioenergetics and the sexual dimorphic nature of bone material properties in C57Bl/6 mice. © 2022 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Hope D. Welhaven
- Department of Chemistry & Biochemistry Montana State University Bozeman MT
- Molecular Biosciences Program Montana State University Bozeman MT
| | - Ghazal Vahidi
- Department of Mechanical & Industrial Engineering Montana State University Bozeman MT
| | - Seth T. Walk
- Department of Microbiology and Cell Biology Montana State University Bozeman MT
| | - Brian Bothner
- Department of Chemistry & Biochemistry Montana State University Bozeman MT
| | - Stephen A. Martin
- Translational Biomarkers Core Laboratory Montana State University Bozeman MT
| | - Chelsea M. Heveran
- Department of Mechanical & Industrial Engineering Montana State University Bozeman MT
| | - Ronald K. June
- Department of Mechanical & Industrial Engineering Montana State University Bozeman MT
- Department of Microbiology and Cell Biology Montana State University Bozeman MT
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13
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Turner RT, Nesser KL, Philbrick KA, Wong CP, Olson DA, Branscum AJ, Iwaniec UT. Leptin and environmental temperature as determinants of bone marrow adiposity in female mice. Front Endocrinol (Lausanne) 2022; 13:959743. [PMID: 36277726 PMCID: PMC9582271 DOI: 10.3389/fendo.2022.959743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 09/15/2022] [Indexed: 11/21/2022] Open
Abstract
Bone marrow adipose tissue (BMAT) levels are higher in distal femur metaphysis of female mice housed at thermoneutral (32°C) than in mice housed at 22°C, as are abdominal white adipose tissue (WAT) mass, and serum leptin levels. We performed two experiments to explore the role of increased leptin in temperature-enhanced accrual of BMAT. First, we supplemented 6-week-old female C57BL/6J (B6) mice with leptin for 2 weeks at 10 µg/d using a subcutaneously implanted osmotic pump. Controls consisted of ad libitum (ad lib) fed mice and mice pair fed to match food intake of leptin-supplemented mice. The mice were maintained at 32°C for the duration of treatment. At necropsy, serum leptin in leptin-supplemented mice did not differ from ad lib mice, suggesting suppression of endogenous leptin production. In support, Ucp1 expression in BAT, percent body fat, and abdominal WAT mass were lower in leptin-supplemented mice. Leptin-supplemented mice also had lower BMAT and higher bone formation in distal femur metaphysis compared to the ad lib group, changes not replicated by pair-feeding. In the second experiment, BMAT response was evaluated in 6-week-old female B6 wild type (WT), leptin-deficient ob/ob and leptin-treated (0.3 μg/d) ob/ob mice housed at 32°C for the 2-week duration of the treatment. Compared to mice sacrificed at baseline (22°C), BMAT increased in ob/ob mice as well as WT mice, indicating a leptin independent response to increased temperature. However, infusion of ob/ob mice with leptin, at a dose rate having negligible effects on either energy metabolism or serum leptin levels, attenuated the increase in BMAT. In summary, increased housing temperature and increased leptin have independent but opposing effects on BMAT in mice.
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Affiliation(s)
- Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, United States
| | - Kira L. Nesser
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Kenneth A. Philbrick
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Carmen P. Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Dawn A. Olson
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, United States
- *Correspondence: Urszula T. Iwaniec,
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14
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Garg P, Strigini M, Peurière L, Vico L, Iandolo D. The Skeletal Cellular and Molecular Underpinning of the Murine Hindlimb Unloading Model. Front Physiol 2021; 12:749464. [PMID: 34737712 PMCID: PMC8562483 DOI: 10.3389/fphys.2021.749464] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 09/23/2021] [Indexed: 01/08/2023] Open
Abstract
Bone adaptation to spaceflight results in bone loss at weight bearing sites following the absence of the stimulus represented by ground force. The rodent hindlimb unloading model was designed to mimic the loss of mechanical loading experienced by astronauts in spaceflight to better understand the mechanisms causing this disuse-induced bone loss. The model has also been largely adopted to study disuse osteopenia and therefore to test drugs for its treatment. Loss of trabecular and cortical bone is observed in long bones of hindlimbs in tail-suspended rodents. Over the years, osteocytes have been shown to play a key role in sensing mechanical stress/stimulus via the ECM-integrin-cytoskeletal axis and to respond to it by regulating different cytokines such as SOST and RANKL. Colder experimental environments (~20-22°C) below thermoneutral temperatures (~28-32°C) exacerbate bone loss. Hence, it is important to consider the role of environmental temperatures on the experimental outcomes. We provide insights into the cellular and molecular pathways that have been shown to play a role in the hindlimb unloading and recommendations to minimize the effects of conditions that we refer to as confounding factors.
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Affiliation(s)
- Priyanka Garg
- INSERM, U1059 Sainbiose, Université Jean Monnet, Mines Saint-Étienne, Université de Lyon, Saint-Étienne, France
| | - Maura Strigini
- INSERM, U1059 Sainbiose, Université Jean Monnet, Mines Saint-Étienne, Université de Lyon, Saint-Étienne, France
| | - Laura Peurière
- INSERM, U1059 Sainbiose, Université Jean Monnet, Mines Saint-Étienne, Université de Lyon, Saint-Étienne, France
| | - Laurence Vico
- INSERM, U1059 Sainbiose, Université Jean Monnet, Mines Saint-Étienne, Université de Lyon, Saint-Étienne, France
| | - Donata Iandolo
- INSERM, U1059 Sainbiose, Université Jean Monnet, Mines Saint-Étienne, Université de Lyon, Saint-Étienne, France
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15
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Kunst RF, Langlais AL, Barlow D, Houseknecht KL, Motyl KJ. Housing Temperature Influences Atypical Antipsychotic Drug-Induced Bone Loss in Female C57BL/6J Mice. JBMR Plus 2021; 5:e10541. [PMID: 34693191 PMCID: PMC8520062 DOI: 10.1002/jbm4.10541] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/01/2021] [Accepted: 08/13/2021] [Indexed: 12/15/2022] Open
Abstract
Atypical antipsychotic (AA) drugs, such as risperidone, are associated with endocrine and metabolic side effects, including impaired bone mineral density (BMD) acquisition and increased fracture risk. We have previously shown that risperidone causes bone loss through the sympathetic nervous system and that bone loss is associated with elevated markers of thermogenesis in brown and white adipose tissue. Because rodents are normally housed in sub‐thermoneutral conditions, we wanted to test whether increasing housing temperature would protect against bone loss from risperidone. Four weeks of risperidone treatment in female C57BL/6J mice at thermoneutral (28°C) housing attenuated risperidone‐induced trabecular bone loss and led to a low‐turnover bone phenotype, with indices of both bone formation and resorption suppressed in mice with risperidone treatment at thermoneutrality, whereas indices of bone resorption were elevated by risperidone at room temperature. Protection against trabecular bone loss was not absolute, however, and additional evidence of cortical bone loss emerged in risperidone‐treated mice at thermoneutrality. Taken together, these findings suggest thermal challenge may be in part responsible for bone loss with risperidone treatment and that housing temperature should be considered when assessing bone outcomes of treatments that impact thermogenic pathways. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Roni F Kunst
- Center for Molecular Medicine Maine Medical Center Research Institute Scarborough ME USA
| | - Audrie L Langlais
- Center for Molecular Medicine Maine Medical Center Research Institute Scarborough ME USA.,Graduate School of Biomedical Sciences and Engineering, University of Maine Orono ME USA
| | - Deborah Barlow
- College of Osteopathic Medicine, University of New England Biddeford ME USA
| | | | - Katherine J Motyl
- Center for Molecular Medicine Maine Medical Center Research Institute Scarborough ME USA.,Graduate School of Biomedical Sciences and Engineering, University of Maine Orono ME USA.,Tufts University School of Medicine, Tufts University Boston MA USA
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16
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Martin SA, Riordan RT, Wang R, Yu Z, Aguirre-Burk AM, Wong CP, Olson DA, Branscum AJ, Turner RT, Iwaniec UT, Perez VI. Rapamycin impairs bone accrual in young adult mice independent of Nrf2. Exp Gerontol 2021; 154:111516. [PMID: 34389472 DOI: 10.1016/j.exger.2021.111516] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Revised: 07/15/2021] [Accepted: 08/08/2021] [Indexed: 11/17/2022]
Abstract
Advanced age is the strongest risk factor for osteoporosis. The immunomodulator drug rapamycin extends lifespan in numerous experimental model organisms and is being investigated as a potential therapeutic to slow human aging, but little is known about the effects of rapamycin on bone. We evaluated the impact of rapamycin treatment on bone mass, architecture, and indices of bone turnover in healthy adult (16-20 weeks old at treatment initiation) female wild-type (ICR) and Nrf2-/- mice, a mouse model of oxidative damage and aging-related disease vulnerability. Rapamycin (4 mg/kg bodyweight) was administered by intraperitoneal injection every other day for 12 weeks. Mice treated with rapamycin exhibited lower femur bone mineral content, bone mineral density, and bone volume compared to vehicle-treated mice. In midshaft femur diaphysis (cortical bone), rapamycin-treated mice had lower cortical volume and thickness, and in the distal femur metaphysis (cancellous bone), rapamycin-treated mice had higher trabecular spacing and lower connectivity density. Mice treated with rapamycin exhibited lower bone volume, bone volume fraction, and trabecular thickness in the 5th lumbar vertebra. Rapamycin-treated mice had lower levels of bone formation in the distal femur metaphysis compared to vehicle-treated mice which occurred co-incidentally with increased serum CTX-1, a marker of global bone resorption. Rapamycin had no impact on tibia inflammatory cytokine gene expression, and we found no independent effects of Nrf2 knockout on bone, nor did we find any interactions between genotype and treatment. These data show that rapamycin may have a negative impact on the skeleton of adult mice that should not be overlooked in the clinical context of its usage as a therapy to retard aging and reduce the incidence of age-related pathologies.
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Affiliation(s)
- Stephen A Martin
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA; Biology of Aging Laboratory, Center for American Indian and Rural Health Equity, Montana State University, Bozeman, MT 59718, USA.
| | - Ruben T Riordan
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA; Department Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
| | - Rong Wang
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA
| | - Zhen Yu
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA
| | - Allan M Aguirre-Burk
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Carmen P Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Dawn A Olson
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Adam J Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Russell T Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Urszula T Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR 97331, USA
| | - Viviana I Perez
- Linus Pauling Institute, Oregon State University, Corvallis, OR 97331, USA; Department Biochemistry and Biophysics, Oregon State University, Corvallis, OR 97331, USA
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17
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Evidence for increased thermogenesis in female C57BL/6J mice housed aboard the international space station. NPJ Microgravity 2021; 7:23. [PMID: 34145277 PMCID: PMC8213760 DOI: 10.1038/s41526-021-00150-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 05/12/2021] [Indexed: 11/09/2022] Open
Abstract
Sixteen-week-old female C57BL/6J mice were sacrificed aboard the International Space Station after 37 days of flight (RR-1 mission) and frozen carcasses returned to Earth. RNA was isolated from interscapular brown adipose tissue (BAT) and gonadal white adipose tissue (WAT). Spaceflight resulted in differential expression of genes in BAT consistent with increased non-shivering thermogenesis and differential expression of genes in WAT consistent with increased glucose uptake and metabolism, adipogenesis, and β-oxidation.
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18
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Lelis Carvalho A, Treyball A, Brooks DJ, Costa S, Neilson RJ, Reagan MR, Bouxsein ML, Motyl KJ. TRPM8 modulates temperature regulation in a sex-dependent manner without affecting cold-induced bone loss. PLoS One 2021; 16:e0231060. [PMID: 34086678 PMCID: PMC8177490 DOI: 10.1371/journal.pone.0231060] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Accepted: 05/06/2021] [Indexed: 01/12/2023] Open
Abstract
Trpm8 (transient receptor potential cation channel, subfamily M, member 8) is expressed by sensory neurons and is involved in the detection of environmental cold temperatures. TRPM8 activity triggers an increase in uncoupling protein 1 (Ucp1)-dependent brown adipose tissue (BAT) thermogenesis. Bone density and marrow adipose tissue are both influenced by rodent housing temperature and brown adipose tissue, but it is unknown if TRPM8 is involved in the co-regulation of thermogenesis and bone homeostasis. To address this, we examined the bone phenotypes of one-year-old Trpm8 knockout mice (Trpm8-KO) after a 4-week cold temperature challenge. Male Trpm8-KO mice had lower bone mineral density than WT, with smaller bone size (femur length and cross-sectional area) being the most striking finding, and exhibited a delayed cold acclimation with increased BAT expression of Dio2 and Cidea compared to WT. In contrast to males, female Trpm8-KO mice had low vertebral bone microarchitectural parameters, but no genotype-specific alterations in body temperature. Interestingly, Trpm8 was not required for cold-induced trabecular bone loss in either sex, but bone marrow adipose tissue in females was significantly suppressed by Trpm8 deletion. In summary, we identified sex differences in the role of TRPM8 in maintaining body temperature, bone microarchitecture and marrow adipose tissue. Identifying mechanisms through which cold temperature and BAT influence bone could help to ameliorate potential bone side effects of obesity treatments designed to stimulate thermogenesis.
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Affiliation(s)
- Adriana Lelis Carvalho
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States of America
| | - Annika Treyball
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States of America
| | - Daniel J. Brooks
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, United States of America
| | - Samantha Costa
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States of America
| | - Ryan J. Neilson
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States of America
| | - Michaela R. Reagan
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States of America
- Tufts University School of Medicine, Tufts University, Boston, MA, United States of America
- Graduate School of Biomedical Sciences and Engineering, The University of Maine, Orono, ME, United States of America
| | - Mary L. Bouxsein
- Center for Advanced Orthopaedic Studies, Beth Israel Deaconess Medical Center, Boston, MA, United States of America
- Department of Orthopedic Surgery, Harvard Medical School, Boston, MA, United States of America
| | - Katherine J. Motyl
- Center for Molecular Medicine, Maine Medical Center Research Institute, Scarborough, ME, United States of America
- Tufts University School of Medicine, Tufts University, Boston, MA, United States of America
- Graduate School of Biomedical Sciences and Engineering, The University of Maine, Orono, ME, United States of America
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19
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Mao L, Guo J, Hu L, Li L, Xu J, Zou J. The effects of biophysical stimulation on osteogenic differentiation and the mechanisms from ncRNAs. Cell Biochem Funct 2021; 39:727-739. [PMID: 34041775 DOI: 10.1002/cbf.3650] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 05/07/2021] [Accepted: 05/10/2021] [Indexed: 01/02/2023]
Abstract
Ample proof showed that non-coding RNAs (ncRNAs) play a crucial role in proliferation and differentiation of osteoblasts and bone marrow stromal cells (BMSCs). Varied forms of biophysical stimuli like mechanical strain, fluid shear stress (FSS), microgravity and vibration are verified to regulate ncRNAs expression in osteogenic differentiation and influence the expression of target genes associated with osteogenic differentiation and ultimately regulate bone formation. The consequences of biophysical stimulation on osteogenic differentiation validate the prospect of exercise for the prevention and treatment of osteoporosis. In this review, we tend to summarize the studies on regulation of osteogenic differentiation by ncRNAs beneath biophysical stimulation and facilitate to reveal the regulatory mechanism of biophysical stimulation on ncRNAs, and provide an update for the prevention of bone metabolism diseases by exercise.
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Affiliation(s)
- Liwei Mao
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Jianmin Guo
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Linghui Hu
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Lexuan Li
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
| | - Jiake Xu
- School of Biomedical Sciences, The University of Western Australia, Perth, Western Australia, Australia
| | - Jun Zou
- School of Kinesiology, Shanghai University of Sport, Shanghai, China
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20
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Tastad CA, Kohler R, Wallace JM. Limited impacts of thermoneutral housing on bone morphology and mechanical properties in growing female mice exposed to external loading and raloxifene treatment. Bone 2021; 146:115889. [PMID: 33618075 PMCID: PMC8009860 DOI: 10.1016/j.bone.2021.115889] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2020] [Revised: 02/10/2021] [Accepted: 02/11/2021] [Indexed: 12/29/2022]
Abstract
Thermoregulation is an important factor that could have physiological consequences on pre-clinical research outcomes. Simply housing mice at thermoneutral temperature has been shown to prevent the well-established loss of cancellous bone that is typical in growing mice. In this study, active tissue formation was induced by non-invasive tibial loading in female mice and combined with raloxifene treatment to assess whether temperature could enhance their combined effects on bone morphology and mechanical properties. It was hypothesized that by removing the cold stress under which normal lab mice are housed, a metabolic boost would allow for further architectural and mechanical improvements in mice exposed to a combination of tibial loading and raloxifene. Ten-week old female C57BL/6J mice were treated with raloxifene, underwent tibial loading to a maximum tensile stress of 2050 με, and were housed in thermoneutral conditions (32 °C) for 6 weeks. We investigated bone morphology through microcomputed tomography (μCT), mechanical properties via four-point bending, and fracture toughness testing. Results confirmed previous work showing a combined effect of external loading and raloxifene which led to greater improvements in most properties than either individual treatment. Counter to the hypothesis, temperature had modest effects on body weight, overall bone size, and trabecular architecture, and most effects were detrimental. Thermoneutrality had no impact on mechanical integrity or fracture toughness. In most cases, the magnitude of temperature-based effects were less robust than either RAL treatment or loading.
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Affiliation(s)
- Carli A Tastad
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, USA
| | - Rachel Kohler
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, USA
| | - Joseph M Wallace
- Department of Biomedical Engineering, Indiana University-Purdue University at Indianapolis, Indianapolis, IN, USA.
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21
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Okla M, Kassem M. Thermogenic potentials of bone marrow adipocytes. Bone 2021; 143:115658. [PMID: 32979539 DOI: 10.1016/j.bone.2020.115658] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 09/18/2020] [Accepted: 09/19/2020] [Indexed: 12/31/2022]
Abstract
Bone marrow adipose tissue (MAT) is a unique fat depot located in proximity to bone surfaces and exerts regulatory functions in the skeleton. Recent studies have demonstrated that MAT responds to changes in whole-body energy metabolism, such as in obesity and anorexia nervosa, where MAT expands, resulting in deleterious effects on the skeleton. Interestingly, MAT shares properties with both brown and white adipose tissues but exhibits distinct features with regard to lipid metabolism and insulin sensitivity. Recent reports have addressed the capacity of MAT to undergo browning, which could be an attractive strategy for preventing excessive MAT accumulation within the skeleton. In this review, we summarize studies addressing the browning phenomenon of MAT and its regulation by a number of pathophysiological conditions. Moreover, we discuss the relationship between adaptive thermogenesis and bone health. Understanding the thermogenic potentials of MAT will delineate the biological importance of this organ and unravel its potential for improving bone health and whole-body energy metabolism.
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Affiliation(s)
- Meshail Okla
- Department of Community Health Sciences, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia; Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
| | - Moustapha Kassem
- Stem Cell Unit, Department of Anatomy, College of Medicine, King Saud University, Riyadh, Saudi Arabia; Department of Molecular Endocrinology, KMEB, University of Southern Denmark, Odense University Hospital, 5000 Odense C, Denmark; Department of Cellular and Molecular Medicine, The Novo Nordisk Foundation Center for Stem Cell Biology (DanStem), Panum Institute, University of Copenhagen, Copenhagen, Denmark
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22
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Du J, He Z, Xu M, Qu X, Cui J, Zhang S, Zhang S, Li H, Yu Z. Brown Adipose Tissue Rescues Bone Loss Induced by Cold Exposure. Front Endocrinol (Lausanne) 2021; 12:778019. [PMID: 35126308 PMCID: PMC8811040 DOI: 10.3389/fendo.2021.778019] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 12/27/2021] [Indexed: 12/11/2022] Open
Abstract
Cold temperature activates the sympathetic nervous system (SNS) to induce bone loss by altering bone remodeling. Brown adipose tissue (BAT) is influenced by the SNS in cold environments. Many studies have confirmed a positive relationship between BAT volume and bone mass, but the influence and mechanism of BAT on bone in vivo and in vitro is still unknown. Two-month-old C57/BL6j male mice were exposed to cold temperature (4°C) to induce BAT generation. BAT volume, bone remodeling and microstructure were assessed after 1 day, 14 days and 28 days of cold exposure. CTX-1, P1NP and IL-6 levels were detected in the serum by ELISA. To determine the effect of BAT on osteoclasts and osteoblasts in vitro, brown adipocyte conditional medium (BAT CM) was collected and added to the differentiation medium of bone marrow-derived macrophages (BMMs) and bone marrow mesenchymal stem cells (BMSCs). Micro-CT results showed that the bone volume fraction (BV/TV, %) significantly decreased after 14 days of exposure to cold temperature but recovered after 28 days. Double labeling and TRAP staining in vivo showed that bone remodeling was altered during cold exposure. BAT volume enlarged after 14 days of cold stimulation, and IL-6 increased. BAT CM promoted BMSC mineralization by increasing osteocalcin (Ocn), RUNX family transcription factor 2 (Runx2) and alkaline phosphatase (Alp) expression, while bone absorption was inhibited by BAT CM. In conclusion, restoration of bone volume after cold exposure may be attributed to enlarged BAT. BAT has a beneficial effect on bone mass by facilitating osteogenesis and suppressing osteoclastogenesis.
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Affiliation(s)
- Jingke Du
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Knee Surgery Department of the Institute of Sports Medicine, Beijing Key Laboratory of Sports Injuries, Peking University Third Hospital, Beijing, China
| | - Zihao He
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- Arthritis Clinic and Research Center, Peking University People’s Hospital, Peking University, Beijing, China
| | - Mingming Xu
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Xinhua Qu
- Department of Bone and Joint Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Junqi Cui
- Department of Pathology, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuangyan Zhang
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Shuhong Zhang
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Hanjun Li
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Zhifeng Yu, ; Hanjun Li,
| | - Zhifeng Yu
- Shanghai Key Laboratory of Orthopedic Implants, Department of Orthopedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China
- *Correspondence: Zhifeng Yu, ; Hanjun Li,
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23
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Wee NKY, Nguyen AD, Enriquez RF, Zhang L, Herzog H, Baldock PA. Neuropeptide Y Regulation of Energy Partitioning and Bone Mass During Cold Exposure. Calcif Tissue Int 2020; 107:510-523. [PMID: 32804252 DOI: 10.1007/s00223-020-00745-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 08/04/2020] [Indexed: 10/23/2022]
Abstract
The maintenance of whole body energy homeostasis is critical to survival and mechanisms exist whereby an organism can adapt to its environment and the stresses placed upon it. Environmental temperature and thermogenesis are key components known to affect energy balance. However, little is known about how these processes are balanced against the overall energy balance. We show that even mild cold exposure has a significant effect on energy expenditure and UCP-1 levels which increase by 43% and 400%, respectively, when wild-type (WT) mice at thermoneutral (29 °C) were compared to mice at room temperature (22 °C) conditions. Interestingly, bone mass was lower in cold-stressed WT mice with significant reductions in femoral bone mineral content (- 19%) and bone volume (- 13%). Importantly, these cold-induced skeletal changes were absent in mice lacking NPY, one of the main controllers of energy homeostasis, highlighting the critical role of NPY in this process. However, energy expenditure was significantly greater in cold-exposed NPY null mice, indicating that suppression of non-thermogenic tissues, like bone, contributes to the adaptive responses to cold exposure. Altogether, this work identifies NPY as being crucial in coordinating energy and bone homeostasis where it suppresses energy expenditure, UCP-1 levels and lowers bone mass under conditions of cold exposure.
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Affiliation(s)
- Natalie K Y Wee
- Bone Biology Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Amy D Nguyen
- Neuroscience Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Ronaldo F Enriquez
- Bone Biology Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Lei Zhang
- Neuroscience Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
| | - Herbert Herzog
- Neuroscience Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia
- School of Medical Sciences, University of NSW, Sydney, NSW, Australia
| | - Paul A Baldock
- Bone Biology Division, Garvan Institute of Medical Research, 384 Victoria Street, Darlinghurst, Sydney, NSW, 2010, Australia.
- School of Medical Sciences, University of NSW, Sydney, NSW, Australia.
- School of Medicine Sydney, University of Notre Dame Australia, Sydney, Australia.
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24
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Housing temperature influences exercise training adaptations in mice. Nat Commun 2020; 11:1560. [PMID: 32214091 PMCID: PMC7096511 DOI: 10.1038/s41467-020-15311-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 02/27/2020] [Indexed: 01/14/2023] Open
Abstract
Exercise training is a powerful means to combat metabolic diseases. Mice are extensively used to investigate the benefits of exercise, but mild cold stress induced by ambient housing temperatures may confound translation to humans. Thermoneutral housing is a strategy to make mice more metabolically similar to humans but its effects on exercise adaptations are unknown. Here we show that thermoneutral housing blunts exercise-induced improvements in insulin action in muscle and adipose tissue and reduces the effects of training on energy expenditure, body composition, and muscle and adipose tissue protein expressions. Thus, many reported effects of exercise training in mice are likely secondary to metabolic stress of ambient housing temperature, making it challenging to translate to humans. We conclude that adaptations to exercise training in mice critically depend upon housing temperature. Our findings underscore housing temperature as a critical parameter in the design and interpretation of murine exercise training studies. Exercise has been shown to be an effective approach to ameliorate metabolic disease in mice housed at ambient temperatures, a condition of mild cold stress to mice. Here the authors show that molecular and metabolic adaptations to exercise are blunted when mice are housed in thermoneutral conditions.
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25
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Turner RT, Philbrick KA, Wong CP, Gamboa AR, Branscum AJ, Iwaniec UT. Effects of Propranolol on Bone, White Adipose Tissue, and Bone Marrow Adipose Tissue in Mice Housed at Room Temperature or Thermoneutral Temperature. Front Endocrinol (Lausanne) 2020; 11:117. [PMID: 32256446 PMCID: PMC7089918 DOI: 10.3389/fendo.2020.00117] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 02/21/2020] [Indexed: 12/16/2022] Open
Abstract
Growing female mice housed at room temperature (22°C) weigh the same but differ in body composition compared to mice housed at thermoneutrality (32°C). Specifically, mice housed at room temperature have lower levels of white adipose tissue (WAT). Additionally, bone marrow adipose tissue (bMAT) and cancellous bone volume fraction in distal femur metaphysis are lower in room temperature-housed mice. The metabolic changes induced by sub-thermoneutral housing are associated with lower leptin levels in serum and higher levels of Ucp1 gene expression in brown adipose tissue. Although the precise mechanisms mediating adaptation to sub-thermoneutral temperature stress remain to be elucidated, there is evidence that increased sympathetic nervous system activity acting via β-adrenergic receptors plays an important role. We therefore evaluated the effect of the non-specific β-blocker propranolol (primarily β1 and β2 antagonist) on body composition, femur microarchitecture, and bMAT in growing female C57BL/6 mice housed at either room temperature or thermoneutral temperature. As anticipated, cancellous bone volume fraction, WAT and bMAT were lower in mice housed at room temperature. Propranolol had small but significant effects on bone microarchitecture (increased trabecular number and decreased trabecular spacing), but did not attenuate premature bone loss induced by room temperature housing. In contrast, propranolol treatment prevented housing temperature-associated differences in WAT and bMAT. To gain additional insight, we evaluated a panel of genes in tibia, using an adipogenesis PCR array. Housing temperature and treatment with propranolol had exclusive as well as shared effects on gene expression. Of particular interest was the finding that room temperature housing reduced, whereas propranolol increased, expression of the gene for acetyl-CoA carboxylase (Acacb), the rate-limiting step for fatty acid synthesis and a key regulator of β-oxidation. Taken together, these findings provide evidence that increased activation of β1 and/or β2 receptors contributes to reduced bMAT by regulating adipocyte metabolism, but that this pathway is unlikely to be responsible for premature cancellous bone loss in room temperature-housed mice.
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Affiliation(s)
- Russell T. Turner
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, United States
| | - Kenneth A. Philbrick
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Carmen P. Wong
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Amanda R. Gamboa
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Adam J. Branscum
- Biostatistics Program, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
| | - Urszula T. Iwaniec
- Skeletal Biology Laboratory, School of Biological and Population Health Sciences, Oregon State University, Corvallis, OR, United States
- Center for Healthy Aging Research, Oregon State University, Corvallis, OR, United States
- *Correspondence: Urszula T. Iwaniec
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