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Basmaison O, Ranchin B, Zouater H, Robertson A, Gomez R, Koppiker N. Efficacy and safety of recombinant growth hormone treatment in children with growth retardation related to long-term glucocorticosteroid therapy. ANNALES D'ENDOCRINOLOGIE 2019; 80:202-210. [PMID: 30910221 DOI: 10.1016/j.ando.2019.02.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2017] [Revised: 02/02/2018] [Accepted: 02/22/2019] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To evaluate safety and efficacy of recombinant human growth hormone treatment in children on long-term glucocorticoid therapy. METHODS A 5-year prospective open-label study included children on glucocorticoid therapy with either standard deviation score (SDS)<-2 for height for chronological age (CA) if naïve to growth hormone treatment, or annual growth rate≥0 SDS for CA if currently receiving growth hormone. RESULTS Ninety-eight patients began treatment, 63 discontinued; 59 were analyzed for safety and 58 for efficacy. There was male predominance (78.0%). Median age was 13.0 years. Median height screening was 136.0cm (range, 95.1-159.7cm). Mean SDS for height for CA in the efficacy analysis set was -2.91±1.19 (range, -7.49 to -0.96). Mean growth hormone dose was 0.4, 0.4, 0.4 and 0.3mg/kg/week at month 0, M12, M24, and M36, respectively. Primary analysis of change in SDS for height for CA from baseline to M36 showed a significant increase of 0.80±1.03. Twenty patients in the safety analysis set had≥1 treatment-emergent adverse event (TEAE) related to study treatment. Two patients experienced serious treatment-related TEAEs: 1 case of poor compliance, and 1 of mild hyperglycemia, both already observed under growth hormone treatment. CONCLUSION This study suggests that growth hormone treatment could be effective in increasing height in children on long-term glucocorticoid treatment with a safety profile comparable to that in approved rhGH treatment indications. CLINICAL TRIAL REGISTRATION NCT00163189.
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Affiliation(s)
- Odile Basmaison
- Pediatric Nephrology Unit, Hôpital Femme-Mère-Enfant, Hospices Civils de Lyon, 69677 Bron Cedex, France
| | - Bruno Ranchin
- Pediatric Nephrology Unit, Hôpital Femme-Mère-Enfant, Hospices Civils de Lyon, 69677 Bron Cedex, France
| | | | - Anna Robertson
- Bevan House, 9-11, Bancroft Court, Hitchin, Hertfordshire, SG5 1LH, United Kingdom
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Zaman F, Zhao Y, Celvin B, Mehta HH, Wan J, Chrysis D, Ohlsson C, Fadeel B, Cohen P, Sävendahl L. Humanin is a novel regulator of Hedgehog signaling and prevents glucocorticoid-induced bone growth impairment. FASEB J 2019; 33:4962-4974. [PMID: 30657335 DOI: 10.1096/fj.201801741r] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Glucocorticoids (GCs) are frequently used to treat chronic disorders in children, including inflammation and cancer. Prolonged treatment with GCs is well known to impair bone growth, an effect linked to increased apoptosis and suppressed proliferation in growth plate chondrocytes. We hypothesized that the endogenous antiapoptotic protein humanin (HN) may prevent these effects. Interestingly, GC-induced bone growth impairment and chondrocyte apoptosis was prevented in HN overexpressing mice, HN-treated wild-type mice, and in HN-treated cultured rat metatarsal bones. GC-induced suppression of chondrocyte proliferation was also prevented by HN. Furthermore, GC treatment reduced Indian Hedgehog expression in growth plates of wild-type mice but not in HN overexpressing mice or HN-treated wild-type animals. A Hedgehog (Hh) antagonist, vismodegib, was found to suppress the growth of cultured rat metatarsal bones, and this effect was also prevented by HN. Importantly, HN did not interfere with the desired anti-inflammatory effects of GCs. We conclude that HN is a novel regulator of Hh signaling preventing GC-induced bone growth impairment without interfering with desired effects of GCs. Our data may open for clinical studies exploring a new possible strategy to prevent GC-induced bone growth impairment by cotreating with HN.-Zaman, F., Zhao, Y., Celvin, B., Mehta, H. H., Wan, J., Chrysis, D., Ohlsson, C., Fadeel, B., Cohen, P., Sävendahl, L. Humanin is a novel regulator of Hedgehog signaling and prevents glucocorticoid-induced bone growth impairment.
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Affiliation(s)
- Farasat Zaman
- Department of Women's and Children's Health, Karolinska Institutet and Pediatric Endocrinology Unit, Karolinska University Hospital, Solna, Sweden
| | - Yunhan Zhao
- Department of Women's and Children's Health, Karolinska Institutet and Pediatric Endocrinology Unit, Karolinska University Hospital, Solna, Sweden
| | - Bettina Celvin
- Department of Women's and Children's Health, Karolinska Institutet and Pediatric Endocrinology Unit, Karolinska University Hospital, Solna, Sweden
| | - Hemal H Mehta
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
| | - Junxiang Wan
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
| | - Dionisios Chrysis
- Division of Endocrinology, Department of Pediatrics, Medical School, University of Patras, Patras, Greece
| | - Claes Ohlsson
- Centre for Bone and Arthritis Research at Institute of Medicine, Sahlgrenska Academy at University of Gothenburg, Gothenburg, Sweden; and
| | - Bengt Fadeel
- Division of Molecular Toxicology, Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Pinchas Cohen
- Leonard Davis School of Gerontology, University of Southern California, Los Angeles, California, USA
| | - Lars Sävendahl
- Department of Women's and Children's Health, Karolinska Institutet and Pediatric Endocrinology Unit, Karolinska University Hospital, Solna, Sweden
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Yang YJ, Zhu Z, Wang DT, Zhang XL, Liu YY, Lai WX, Mo YL, Li J, Liang YL, Hu ZQ, Yu YJ, Cui L. Tanshinol alleviates impaired bone formation by inhibiting adipogenesis via KLF15/PPARγ2 signaling in GIO rats. Acta Pharmacol Sin 2018; 39:633-641. [PMID: 29323335 PMCID: PMC5888681 DOI: 10.1038/aps.2017.134] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2017] [Accepted: 09/18/2017] [Indexed: 12/22/2022] Open
Abstract
Glucocorticoid (GC)-induced osteoporosis (GIO) is characterized by impaired bone formation, which can be alleviated by tanshinol, an aqueous polyphenol isolated from Salvia miltiorrhiza Bunge. In this study we investigated the molecular mechanisms underlying GC-induced modulation of osteogenesis as well as the possibility of using tanshinol to interfere with GIO. Female SD rats aged 4 months were orally administered distilled water (Con), prednisone (GC, 5 mg·kg-1·d-1), GC plus tanshinol (Tan, 16 mg·kg-1·d-1) or GC plus resveratrol (Res, 5 mg·kg-1·d-1) for 14 weeks. After the rats were sacrificed, samples of bone tissues were collected. The changes in bone formation were assessed using Micro-CT, histomorphometry, and biomechanical assays. Expression of Kruppel-like factor 15 (KLF15), peroxisome proliferator-activated receptor γ 2 (PPARγ 2) and other signaling proteins in skeletal tissue was measured with Western blotting and quantitative RT-PCR. GC treatment markedly increased the expression of KLF15, PPARγ2, C/EBPα and aP2, which were related to adipogenesis, upregulated FoxO3a pathway proteins (FoxO3a and Gadd45a), and suppressed the canonical Wnt signaling (β-catenin and Axin2), which was required for osteogenesis. Thus, GC significantly decreased bone mass and bone quality. Co-treatment with Tan or Res effectively counteracted GC-impaired bone formation, suppressed GC-induced adipogenesis, and restored abnormal expression of the signaling molecules in GIO rats. We conclude that tanshinol counteracts GC-decreased bone formation by inhibiting marrow adiposity via the KLF15/PPARγ2/FoxO3a/Wnt pathway.
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Affiliation(s)
- Ya-jun Yang
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Zhu Zhu
- Sino-American Cancer Research Institute, Guangdong Medical University, Dongguan 523808, China
| | - Dong-tao Wang
- Department of Traditional Chinese Medicine, Shenzhen Hospital, Southern Medical University, Shenzhen 518000, China
| | - Xin-le Zhang
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Yu-yu Liu
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Wen-xiu Lai
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Yu-lin Mo
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Jin Li
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Yan-long Liang
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Zhuo-qing Hu
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Yong-jie Yu
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
| | - Liao Cui
- Department of Pharmacology, Guangdong Medical University, Zhanjiang 524023, China
- Guangdong Key Laboratory for R&D of Natural Drugs, Guangdong Medical University, Zhanjiang 524023, China
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David H, Aupiais C, Louveau B, Quartier P, Jacqz-Aigrain E, Carel JC, Simon D. Growth Outcomes After GH Therapy of Patients Given Long-Term Corticosteroids for Juvenile Idiopathic Arthritis. J Clin Endocrinol Metab 2017; 102:4578-4587. [PMID: 29029101 DOI: 10.1210/jc.2017-01455] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/29/2017] [Indexed: 11/19/2022]
Abstract
CONTEXT Growth hormone (GH) therapy may improve statural growth outcomes in patients with severe juvenile idiopathic arthritis (JIA). OBJECTIVES To evaluate the effect of GH treatment on adult height and to identify determinants of growth outcomes in JIA. DESIGN AND PATIENTS Data from 58 patients with JIA, including 53 receiving GH, enrolled in three prospective clinical trials between 1997 and 2002 were analyzed. INTERVENTION GH (0.056 mg/kg/d [interquartile range (IQR), 0.050 to 0.062]) for a median duration of 6.5 years (IQR, 4.7 to 7.9 years). MAIN OUTCOME MEASURES Factors associated with a favorable growth outcome (adult height - target height ≤ -1.5 standard deviations) were identified by multivariate logistic regression. RESULTS Adult height was available for 48 patients 8.6 years after GH initiation (IQR, 6.0 to 10.2 years). Height standard deviation score (SDS) increased from -2.9 (IQR, -4.4 to -1.6) at baseline to -1.7 (IQR, -3.9 to -0.1) in adulthood (P < 0.001). Median adult height was below target height [SDS, -0.2 (IQR, -1.4 to 0.4); P < 0.001]. Corrected adult height SDS was -1.3 (IQR, -3.0 to -0.2). Growth outcome was favorable in 24 (52.2%) patients. Significant independent determinants of growth outcome were age at GH initiation [adjusted odds ratio (aOR), 0.68 per additional year; 95% confidence interval (CI), 0.47 to 0.99], height at GH initiation (aOR, 2.6 per additional SDS; 95% CI, 1.15 to 5.9), and mean C-reactive protein levels during follow up (aOR, 0.51 per additional 10 mg/L; 95% CI, 0.28 to 0.92). CONCLUSION Long-term GH treatment significantly increased growth in patients with JIA but did not fully restore the genetic growth potential. The response showed marked interindividual variability and was weaker in patients with severe inflammation.
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Affiliation(s)
- Hélène David
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Service d'Endocrinologie Diabétologie Pédiatrique, Centre de Référence des Maladies Endocriniennes Rares de la Croissance, France
| | - Camille Aupiais
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Unité d'Epidémiologie Clinique Université Paris Diderot, Sorbonne Paris-Cité, INSERM U1123 et CIC-EC 1426, France
- ECEVE UMR1123 et CIC-EC 1426, Université Paris Diderot, Sorbonne Paris-Cité, INSERM, France
| | - Baptiste Louveau
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Unité d'Epidémiologie Clinique Université Paris Diderot, Sorbonne Paris-Cité, INSERM U1123 et CIC-EC 1426, France
| | - Pierre Quartier
- Assistance Publique-Hôpitaux de Paris, Hôpital Necker Enfants Malades, Service d'Immuno-Hématologie et Rhumatologie Pédiatrique, France
- Institut IMAGINE, Université Paris Descartes, France
| | - Evelyne Jacqz-Aigrain
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Service de Pharmacologie Pédiatrique, France
- INSERM, CIC 9202, Université Paris Diderot, Sorbonne Paris Cité, France
| | - Jean-Claude Carel
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Service d'Endocrinologie Diabétologie Pédiatrique, Centre de Référence des Maladies Endocriniennes Rares de la Croissance, France
- Protect INSERM Université Paris Diderot, Sorbonne Paris Cité, France
| | - Dominique Simon
- Assistance Publique-Hôpitaux de Paris, Hôpital Robert Debré, Service d'Endocrinologie Diabétologie Pédiatrique, Centre de Référence des Maladies Endocriniennes Rares de la Croissance, France
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Khelfi A, Azzouz M, Abtroun R, Reggabi M, Alamir B. Myopathies induites par les médicaments. TOXICOLOGIE ANALYTIQUE ET CLINIQUE 2017. [DOI: 10.1016/j.toxac.2016.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Improda N, Capalbo D, Esposito A, Salerno M. Muscle and skeletal health in children and adolescents with GH deficiency. Best Pract Res Clin Endocrinol Metab 2016; 30:771-783. [PMID: 27974190 DOI: 10.1016/j.beem.2016.11.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
In addition to promoting linear growth, GH plays a key role in the regulation of bone and muscle development and metabolism. Although GH deficiency is frequently listed among the causes of secondary osteoporosis in children, its impact on bone and muscle health and on fracture risk is still not completely established. Current data suggest that childhood-onset GH deficiency can affect bone and muscle mass and strength, with GH replacement therapy exerting beneficial effects. Moreover, GH withdrawal at final height can result in reduced peak bone and muscle mass, potentially leading to increased fracture risk in adulthood. Thus, the muscle-bone unit in GH deficient subjects should be monitored during childhood and adolescence in order to prevent osteoporosis and increased fracture risk and GH replacement should be tailored to ensure an optimal bone and muscle health.
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Affiliation(s)
- Nicola Improda
- Department of Medical Translational Sciences, Paediatric Endocrinology Section, Federico II University, Via S. Pansini 5, 80131 Naples, Italy.
| | - Donatella Capalbo
- Department of Paediatrics, Federico II University, Via S. Pansini 5, 80131 Naples, Italy.
| | - Andrea Esposito
- Department of Medical Translational Sciences, Paediatric Endocrinology Section, Federico II University, Via S. Pansini 5, 80131 Naples, Italy.
| | - Mariacarolina Salerno
- Department of Medical Translational Sciences, Paediatric Endocrinology Section, Federico II University, Via S. Pansini 5, 80131 Naples, Italy.
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O'Connell KE, Guo W, Serra C, Beck M, Wachtman L, Hoggatt A, Xia D, Pearson C, Knight H, O'Connell M, Miller AD, Westmoreland SV, Bhasin S. The effects of an ActRIIb receptor Fc fusion protein ligand trap in juvenile simian immunodeficiency virus-infected rhesus macaques. FASEB J 2014; 29:1165-75. [PMID: 25466897 DOI: 10.1096/fj.14-257543] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 11/05/2014] [Indexed: 01/16/2023]
Abstract
There are no approved therapies for muscle wasting in children infected with human immunodeficiency virus (HIV), which portends poor disease outcomes. To determine whether a soluble ActRIIb receptor Fc fusion protein (ActRIIB.Fc), a ligand trap for TGF-β/activin family members including myostatin, can prevent or restore loss of lean body mass and body weight in simian immunodeficiency virus (SIV)-infected juvenile rhesus macaques (Macaca mulatta). Fourteen pair-housed, juvenile male rhesus macaques were inoculated with SIVmac239 and, 4 wk postinoculation (WPI) treated with intramuscular injections of 10 mg ⋅ kg(-1) ⋅ wk(-1) ActRIIB.Fc or saline placebo. Body weight, lean body mass, SIV titers, and somatometric measurements were assessed monthly for 16 wk. Age-matched SIV-infected rhesus macaques were injected with saline. Intervention groups did not differ at baseline. Gains in lean mass were significantly greater in the ActRIIB.Fc group than in the placebo group (P < 0.001). Administration of ActRIIB.Fc was associated with greater gains in body weight (P = 0.01) and upper arm circumference than placebo. Serum CD4(+) T-lymphocyte counts and SIV copy numbers did not differ between groups. Administration of ActRIIB.Fc was associated with higher muscle expression of myostatin than placebo. ActRIIB.Fc effectively blocked and reversed loss of body weight, lean mass, and fat mass in juvenile SIV-infected rhesus macaques.
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Affiliation(s)
- Karyn E O'Connell
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Wen Guo
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Carlo Serra
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew Beck
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Lynn Wachtman
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Amber Hoggatt
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Dongling Xia
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Chris Pearson
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Heather Knight
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Micheal O'Connell
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Andrew D Miller
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Susan V Westmoreland
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
| | - Shalender Bhasin
- *Department of Comparative Pathology, New England Primate Research Center, Southborough, Massachusetts, USA; and Research Program in Men's Health: Aging and Metabolism, Boston Claude D. Pepper Older Americans Independence Center, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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Curzi D, Lattanzi D, Ciuffoli S, Burattini S, Grindeland RE, Edgerton VR, Roy RR, Tidball JG, Falcieri E. Growth hormone plus resistance exercise attenuate structural changes in rat myotendinous junctions resulting from chronic unloading. Eur J Histochem 2013; 57:e37. [PMID: 24441190 PMCID: PMC3896039 DOI: 10.4081/ejh.2013.e37] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Revised: 10/04/2013] [Accepted: 10/04/2013] [Indexed: 11/23/2022] Open
Abstract
Myotendinous junctions (MTJs) are specialized sites on the muscle surface where forces generated by myofibrils are transmitted across the sarcolemma to the extracellular matrix. At the ultrastructural level, the interface between the sarcolemma and extracellular matrix is highly folded and interdigitated at these junctions. In this study, the effect of exercise and growth hormone (GH) treatments on the changes in MTJ structure that occur during muscle unloading, has been analyzed. Twenty hypophysectomized rats were assigned randomly to one of five groups: ambulatory control, hindlimb unloaded, hindlimb unloaded plus exercise (3 daily bouts of 10 climbs up a ladder with 50% body wt attached to the tail), hindlimb unloaded plus GH (2 daily injections of 1 mg/kg body wt, i.p.), and hindlimb unloaded plus exercise plus GH. MTJs of the plantaris muscle were analyzed by electron microscopy and the contact between muscle and tendon was evaluated using an IL/B ratio, where B is the base and IL is the interface length of MTJ's digit-like processes. After 10 days of unloading, the mean IL/B ratio was significantly lower in unloaded (3.92), unloaded plus exercise (4.18), and unloaded plus GH (5.25) groups than in the ambulatory control (6.39) group. On the opposite, the mean IL/B ratio in the group treated with both exercise and GH (7.3) was similar to control. These findings indicate that the interaction between exercise and GH treatments attenuates the changes in MTJ structure that result from chronic unloading and thus can be used as a countermeasure to these adaptations.
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Affiliation(s)
- D Curzi
- Carlo Bo University of Urbino.
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