Osteoblast-specific overexpression of amphiregulin leads to transient increase in cancellous bone mass in mice

Intermittent PTH treatment increases cancellous bone mass in osteoporosis patients; however, it reveals diverse effects on cortical bone mass. Underlying molecular mechanisms for anabolic PTH actions are largely unknown. Because PTH regulates expression of osteopontin (OPN) in osteoblasts, OPN could be one of the targets of PTH in bone. Therefore, we examined the role of OPN in the PTH actions in bone. Intermittent PTH treatment neither altered whole long-bone bone mineral density nor changed cortical bone mass in wild-type 129 mice, although it enhanced cancellous bone volume as reported previously. In contrast, OPN deficiency induced PTH enhancement of whole-bone bone mineral density as well as cortical bone mass. Strikingly, although PTH suppressed periosteal bone formation rate (BFR) and mineral apposition rate (MAR) in cortical bone in wild type, OPN deficiency induced PTH activation of periosteal BFR and MAR. In cancellous bone, OPN deficiency further enhanced PTH increase in BFR and MAR. Analysis on the cellular bases for these phenomena indicated that OPN deficiency augmented PTH enhancement in the increase in mineralized nodule formation in vitro. OPN deficiency did not alter the levels of PTH enhancement of the excretion of deoxypyridinoline in urine, the osteoclast number in vivo, and tartrate-resistant acid phosphatase-positive cell development in vitro. These observations indicated that OPN deficiency specifically induces PTH activation of periosteal bone formation in the cortical bone envelope.

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Hypothalamic leptin gene therapy reduces body weight without accelerating age-related bone loss

Journal of Endocrinology ◽

10.1530/joe-15-0280 ◽

2015 ◽

Vol 227 (3) ◽

pp. 129-141 ◽

Cited By ~ 6

Author(s):

Russell T Turner ◽

Michael Dube ◽

Adam J Branscum ◽

Carmen P Wong ◽

Dawn A Olson ◽

...

Keyword(s):

Gene Therapy ◽

Body Weight ◽

Bone Loss ◽

Bone Mass ◽

Bone Turnover ◽

Cancellous Bone ◽

Mass Density ◽

Female Rats ◽

Bone Mass Density ◽

Age Related

Excessive weight gain in adults is associated with a variety of negative health outcomes. Unfortunately, dieting, exercise, and pharmacological interventions have had limited long-term success in weight control and can result in detrimental side effects, including accelerating age-related cancellous bone loss. We investigated the efficacy of using hypothalamic leptin gene therapy as an alternative method for reducing weight in skeletally-mature (9 months old) female rats and determined the impact of leptin-induced weight loss on bone mass, density, and microarchitecture, and serum biomarkers of bone turnover (CTx and osteocalcin). Rats were implanted with cannulae in the 3rd ventricle of the hypothalamus and injected with either recombinant adeno-associated virus encoding the gene for rat leptin (rAAV-Leptin,n=7) or a control vector encoding green fluorescent protein (rAAV-GFP,n=10) and sacrificed 18 weeks later. A baseline control group (n=7) was sacrificed at vector administration. rAAV-Leptin-treated rats lost weight (−4±2%) while rAAV-GFP-treated rats gained weight (14±2%) during the study. At study termination, rAAV-Leptin-treated rats weighed 17% less than rAAV-GFP-treated rats and had lower abdominal white adipose tissue weight (−80%), serum leptin (−77%), and serum IGF1 (−34%). Cancellous bone volume fraction in distal femur metaphysis and epiphysis, and in lumbar vertebra tended to be lower (P<0.1) in rAAV-GFP-treated rats (13.5 months old) compared to baseline control rats (9 months old). Significant differences in cancellous bone or biomarkers of bone turnover were not detected between rAAV-Leptin and rAAV-GFP rats. In summary, rAAV-Leptin-treated rats maintained a lower body weight compared to baseline and rAAV-GFP-treated rats with minimal effects on bone mass, density, microarchitecture, or biochemical markers of bone turnover.

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Circum-menarcheal Exercise And Diet As Factors In Cortical And Cortico-cancellous Bone Mass And Strength Indices

Medicine & Science in Sports & Exercise ◽

10.1249/01.mss.0000764544.61107.d5 ◽

2021 ◽

Vol 53 (8S) ◽

pp. 456-456

Author(s):

Jodi N. Dowthwaite ◽

Alexander N. Ruhren ◽

Kailee F. Loiodice ◽

Ye Lin ◽

Tamara A. Scerpella

Keyword(s):

Bone Mass ◽

Cancellous Bone

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Negligible Effect of Estrogen Deficiency on Development of Skeletal Changes Induced by Type 1 Diabetes in Experimental Rat Models

Mediators of Inflammation ◽

10.1155/2020/2793804 ◽

2020 ◽

Vol 2020 ◽

pp. 1-21

Author(s):

Aleksandra Janas ◽

Ewa Kruczek ◽

Piotr Londzin ◽

Sławomir Borymski ◽

Zenon P. Czuba ◽

...

Keyword(s):

Mechanical Properties ◽

Bone Resorption ◽

Bone Mass ◽

Cancellous Bone ◽

Maximum Load ◽

Estrogen Deficiency ◽

Female Rats ◽

Skeletal System ◽

Tibial Metaphysis ◽

Ovx Rats

Although postmenopausal osteoporosis often occurs concurrently with diabetes, little is known about interactions between estrogen deficiency and hyperglycemia in the skeletal system. In the present study, the effects of estrogen deficiency on the development of biochemical, microstructural, and mechanical changes induced by streptozotocin-induced diabetes mellitus (DM) in the rat skeletal system were investigated. The experiments were carried out on nonovariectomized (NOVX) and ovariectomized (OVX) control and diabetic mature female Wistar rats. Serum levels of bone turnover markers (CTX-I and osteocalcin) and 23 cytokines, bone mass and mineralization, histomorphometric parameters, and mechanical properties of cancellous and compact bone were determined. The results were subjected to two-way ANOVA and principal component analysis (PCA). Estrogen deficiency induced osteoporotic changes, with increased bone resorption and formation, and worsening of microstructure (femoral metaphyseal BV/TV decreased by 13.0%) and mechanical properties of cancellous bone (the maximum load in the proximal tibial metaphysis decreased by 34.2%). DM in both the NOVX and OVX rats decreased bone mass, increased bone resorption and decreased bone formation, and worsened cancellous bone microarchitecture (for example, the femoral metaphyseal BV/TV decreased by 17.3% and 18.1%, respectively, in relation to the NOVX controls) and strength (the maximum load in the proximal tibial metaphysis decreased by 35.4% and 48.1%, respectively, in relation to the NOVX controls). Only in the diabetic rats, profound increases in some cytokine levels were noted. In conclusion, the changes induced by DM in female rats were only slightly intensified by estrogen deficiency. Despite similar effects on bone microstructure and strength, the influence of DM on the skeletal system was based on more profound systemic homeostasis changes than those induced by estrogen deficiency.

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Effect of Risedronate on the Cortical and Cancellous Bone Mass and Mechanical Properties in Ovariectomized Rats: A Comparison with the Effects of Alfacalcidol

Journal of Nutritional Science and Vitaminology ◽

10.3177/jnsv.52.393 ◽

2006 ◽

Vol 52 (6) ◽

pp. 393-401 ◽

Cited By ~ 8

Author(s):

Jun IWAMOTO ◽

Azusa SEKI ◽

Tsuyoshi TAKEDA ◽

Yoshihiro SATO ◽

Harumoto YAMADA ◽

...

Keyword(s):

Mechanical Properties ◽

Bone Mass ◽

Cancellous Bone ◽

Ovariectomized Rats

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Association of Collagen Type 1 α1 Gene Polymorphism with Bone Density in Early Childhood1

The Journal of Clinical Endocrinology & Metabolism ◽

10.1210/jcem.84.3.5575 ◽

1999 ◽

Vol 84 (3) ◽

pp. 853-855

Author(s):

Jesus Sainz ◽

Jan M. Van Tornout ◽

James Sayre ◽

Francine Kaufman ◽

Vicente Gilsanz

Keyword(s):

Bone Density ◽

Gene Polymorphism ◽

Bone Mass ◽

Cancellous Bone ◽

Vertebral Fractures ◽

Collagen Type ◽

Elderly Women ◽

Structural Basis ◽

Type I ◽

Vertebral Bone

Osteoporosis is a disease characterized by the development of nontraumatic fractures, most commonly in the vertebrae of elderly women. Approximately 500,000 elderly women in the United States are newly diagnosed with vertebral fractures every year, as the compressive strength of the vertebra, mainly determined by the density of cancellous bone and its cross-sectional area, declines with age. A recent study in women suggested that a polymorphism in the Sp1 binding site of the collagen type I gene (COLIA1) was related to decreased vertebral bone mass and vertebral fractures. Determining the phenotypic trait(s) responsible for this relationship and whether this association is manifested in childhood would further define the structural basis for decreased bone mass and help identify children “at risk” for fractures later in life. We therefore studied the COLIA1 gene polymorphism and measurements of the size and the density of vertebral bone in 109 healthy, prepubertal girls. On average, 22 girls with the Ss genotype and one girl with the ss genotype had 6.7% and 49.4% lower cancellous bone density in the vertebrae than girls with the SS genotype. In contrast, there was no association between the size of the vertebrae and the COLIA1 genotypes.

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A soluble activin type IIA receptor mitigates the loss of femoral neck bone strength and cancellous bone mass in a mouse model of disuse osteopenia

Bone ◽

10.1016/j.bone.2018.02.026 ◽

2018 ◽

Vol 110 ◽

pp. 326-334 ◽

Cited By ~ 6

Author(s):

Andreas Lodberg ◽

Marco Eijken ◽

Bram C.J. van der Eerden ◽

Mette Wendelboe Okkels ◽

Jesper Skovhus Thomsen ◽

...

Keyword(s):

Femoral Neck ◽

Mouse Model ◽

Bone Mass ◽

Bone Strength ◽

Cancellous Bone

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Sex Steroids and the Construction and Conservation of the Adult Skeleton

Endocrine Reviews ◽

10.1210/edrv.23.3.0465 ◽

2002 ◽

Vol 23 (3) ◽

pp. 279-302 ◽

Cited By ~ 752

Author(s):

B. Lawrence Riggs ◽

Sundeep Khosla ◽

L. Joseph Melton

Keyword(s):

Bone Loss ◽

Bone Mass ◽

Cancellous Bone ◽

Sex Steroids ◽

Peak Bone Mass ◽

Dietary Calcium Intake ◽

Growth Spurt ◽

Slow Phase ◽

Age Related ◽

Aging Men

Abstract Here we review and extend a new unitary model for the pathophysiology of involutional osteoporosis that identifies estrogen (E) as the key hormone for maintaining bone mass and E deficiency as the major cause of age-related bone loss in both sexes. Also, both E and testosterone (T) are key regulators of skeletal growth and maturation, and E, together with GH and IGF-I, initiate a 3- to 4-yr pubertal growth spurt that doubles skeletal mass. Although E is required for the attainment of maximal peak bone mass in both sexes, the additional action of T on stimulating periosteal apposition accounts for the larger size and thicker cortices of the adult male skeleton. Aging women undergo two phases of bone loss, whereas aging men undergo only one. In women, the menopause initiates an accelerated phase of predominantly cancellous bone loss that declines rapidly over 4–8 yr to become asymptotic with a subsequent slow phase that continues indefinitely. The accelerated phase results from the loss of the direct restraining effects of E on bone turnover, an action mediated by E receptors in both osteoblasts and osteoclasts. In the ensuing slow phase, the rate of cancellous bone loss is reduced, but the rate of cortical bone loss is unchanged or increased. This phase is mediated largely by secondary hyperparathyroidism that results from the loss of E actions on extraskeletal calcium metabolism. The resultant external calcium losses increase the level of dietary calcium intake that is required to maintain bone balance. Impaired osteoblast function due to E deficiency, aging, or both also contributes to the slow phase of bone loss. Although both serum bioavailable (Bio) E and Bio T decline in aging men, Bio E is the major predictor of their bone loss. Thus, both sex steroids are important for developing peak bone mass, but E deficiency is the major determinant of age-related bone loss in both sexes.

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