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Watkins B, Schultheiß J, Rafuna A, Hintze S, Meinke P, Schoser B, Kröger S. Degeneration of muscle spindles in a murine model of Pompe disease. Sci Rep 2023; 13:6555. [PMID: 37085544 PMCID: PMC10121695 DOI: 10.1038/s41598-023-33543-y] [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: 10/11/2022] [Accepted: 04/14/2023] [Indexed: 04/23/2023] Open
Abstract
Pompe disease is a debilitating medical condition caused by a functional deficiency of lysosomal acid alpha-glucosidase (GAA). In addition to muscle weakness, people living with Pompe disease experience motor coordination deficits including an instable gait and posture. We reasoned that an impaired muscle spindle function might contribute to these deficiencies and therefore analyzed proprioception as well as muscle spindle structure and function in 4- and 8-month-old Gaa-/- mice. Gait analyses showed a reduced inter-limb and inter-paw coordination in Gaa-/- mice. Electrophysiological analyses of single-unit muscle spindle proprioceptive afferents revealed an impaired sensitivity of the dynamic and static component of the stretch response. Finally, a progressive degeneration of the sensory neuron and of the intrafusal fibers was detectable in Gaa-/- mice. We observed an increased abundance and size of lysosomes, a fragmentation of the inner and outer connective tissue capsule and a buildup of autophagic vacuoles in muscle spindles from 8-month-old Gaa-/- mice, indicating lysosomal defects and an impaired autophagocytosis. These results demonstrate a structural and functional degeneration of muscle spindles and an altered motor coordination in Gaa-/- mice. Similar changes could contribute to the impaired motor coordination in patients living with Pompe disease.
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Affiliation(s)
- Bridgette Watkins
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Grosshaderner Strasse 9, 82152, Planegg-Martinsried, Germany
| | - Jürgen Schultheiß
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Grosshaderner Strasse 9, 82152, Planegg-Martinsried, Germany
| | - Andi Rafuna
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Grosshaderner Strasse 9, 82152, Planegg-Martinsried, Germany
| | - Stefan Hintze
- Department of Neurology, Friedrich-Baur-Institute, LMU Klinikum, Ludwig-Maximilians-University, Munich, Germany
| | - Peter Meinke
- Department of Neurology, Friedrich-Baur-Institute, LMU Klinikum, Ludwig-Maximilians-University, Munich, Germany
| | - Benedikt Schoser
- Department of Neurology, Friedrich-Baur-Institute, LMU Klinikum, Ludwig-Maximilians-University, Munich, Germany
| | - Stephan Kröger
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Grosshaderner Strasse 9, 82152, Planegg-Martinsried, Germany.
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Gartych M, Jackowiak H, Bukowska D, Celichowski J. Evaluating Sexual Dimorphism of the Muscle Spindles and Intrafusal Muscle Fibers in the Medial Gastrocnemius of Male and Female Rats. Front Neuroanat 2021; 15:734555. [PMID: 34658799 PMCID: PMC8517148 DOI: 10.3389/fnana.2021.734555] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Accepted: 09/14/2021] [Indexed: 11/27/2022] Open
Abstract
This study sought to investigate the sexual dimorphism of muscle spindles in rat medial gastrocnemius muscle. The muscles were cut transversely into 5–10 and 20 μm thick serial sections and the number, density, and morphometric properties of the muscle spindles were determined. There was no significant difference (p > 0.05) in the number of muscle spindles of male (14.45 ± 2.77) and female (15.00 ± 3.13) rats. Muscle mass was 38.89% higher in males (1.08 vs. 0.66 g in females), making the density of these receptors significantly higher (p < 0.01) in females (approximately one spindle per 51.14 mg muscle mass vs. one per 79.91 mg in males). There were no significant differences between the morphometric properties of intrafusal muscle fibers or muscle spindles in male and female rats (p > 0.05): 5.16 ± 2.43 and 5.37 ± 2.27 μm for male and female intrafusal muscle fiber diameter, respectively; 5.57 ± 2.20 and 5.60 ± 2.16 μm for male and female intrafusal muscle fiber number, respectively; 25.85 ± 10.04 and 25.30 ± 9.96 μm for male and female shorter muscle spindle diameter, respectively; and 48.99 ± 20.73 and 43.97 ± 16.96 μm for male and female longer muscle spindle diameter, respectively. These findings suggest that sexual dimorphism in the muscle spindles of rat medial gastrocnemius is limited to density, which contrasts previous findings reporting differences in extrafusal fibers diameter.
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Affiliation(s)
- Magdalena Gartych
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland
| | - Hanna Jackowiak
- Department of Histology and Embryology, Poznań University of Life Sciences, Poznań, Poland
| | - Dorota Bukowska
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland
| | - Jan Celichowski
- Department of Neurobiology, Poznań University of Physical Education, Poznań, Poland
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Kröger S, Watkins B. Muscle spindle function in healthy and diseased muscle. Skelet Muscle 2021; 11:3. [PMID: 33407830 PMCID: PMC7788844 DOI: 10.1186/s13395-020-00258-x] [Citation(s) in RCA: 39] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Accepted: 12/20/2020] [Indexed: 12/16/2022] Open
Abstract
Almost every muscle contains muscle spindles. These delicate sensory receptors inform the central nervous system (CNS) about changes in the length of individual muscles and the speed of stretching. With this information, the CNS computes the position and movement of our extremities in space, which is a requirement for motor control, for maintaining posture and for a stable gait. Many neuromuscular diseases affect muscle spindle function contributing, among others, to an unstable gait, frequent falls and ataxic behavior in the affected patients. Nevertheless, muscle spindles are usually ignored during examination and analysis of muscle function and when designing therapeutic strategies for neuromuscular diseases. This review summarizes the development and function of muscle spindles and the changes observed under pathological conditions, in particular in the various forms of muscular dystrophies.
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Affiliation(s)
- Stephan Kröger
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University Munich, Großhaderner Str. 9, 82152, Planegg-Martinsried, Germany.
| | - Bridgette Watkins
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University Munich, Großhaderner Str. 9, 82152, Planegg-Martinsried, Germany
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Hendrickse PW, Krusnauskas R, Hodson-Tole E, Venckunas T, Degens H. Endurance exercise plus overload induces fatigue resistance and similar hypertrophy in mice irrespective of muscle mass. Exp Physiol 2020; 105:2110-2122. [PMID: 33140456 DOI: 10.1113/ep089096] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Accepted: 10/28/2020] [Indexed: 12/29/2022]
Abstract
NEW FINDINGS What is the central question of this study? Does combining endurance and hypertrophic stimuli blunt the adaptations to both modalities and is this effect greater in muscles with larger baseline fibre cross sectional area? What is the main finding and its importance? Endurance exercise and hypertrophic stimuli can be combined to increase fatigue resistance and fibre size without blunting either adaptation regardless of baseline fibre size. ABSTRACT Previous studies have demonstrated that fibre cross-sectional area (FCSA) is inversely related to oxidative capacity, which is thought to be determined by diffusion limitations of oxygen, ADP and ATP. Consequently, it is hypothesised that (1) when endurance training is combined with a hypertrophic stimulus the response to each will be blunted, and (2) muscles with a smaller FCSA will show a larger hypertrophic response than those with a large FCSA. To investigate this, we combined overload with endurance exercise in 12-month-old male mice from three different strains with different FCSA: Berlin High (BEH) (large fibres), C57BL/6J (C57) (normal-sized fibres) and Berlin Low (BEL) (small fibres). The right plantaris muscle was subjected to overload through denervation of synergists with the left muscle acting as an internal control. Half the animals trained 30 min per day for 6 weeks. The overload-induced hypertrophy was not blunted by endurance exercise, and the exercise-induced increase in fatigue resistance was not impaired by overload. All strains demonstrated similar absolute increases in FCSA, although the BEH mice with more fibres than the C57 mice demonstrated the largest increase in muscle mass and BEL mice with fewer fibres the smallest increase in muscle mass. This study suggests that endurance exercise and hypertrophic stimuli can be combined without attenuating adaptations to either modality, and that increases in FCSA are independent of baseline fibre size.
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Affiliation(s)
- Paul W Hendrickse
- Department of Life Sciences, Research Centre for Musculoskeletal Science & Sports Medicine, Manchester Metropolitan University, Manchester, UK.,Lithuanian Sports University, Kaunas, Lithuania
| | | | - Emma Hodson-Tole
- Department of Life Sciences, Research Centre for Musculoskeletal Science & Sports Medicine, Manchester Metropolitan University, Manchester, UK
| | | | - Hans Degens
- Department of Life Sciences, Research Centre for Musculoskeletal Science & Sports Medicine, Manchester Metropolitan University, Manchester, UK.,Lithuanian Sports University, Kaunas, Lithuania
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Gerwin L, Rossmanith S, Haupt C, Schultheiß J, Brinkmeier H, Bittner RE, Kröger S. Impaired muscle spindle function in murine models of muscular dystrophy. J Physiol 2020; 598:1591-1609. [PMID: 32003874 DOI: 10.1113/jp278563] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2019] [Accepted: 01/24/2020] [Indexed: 12/13/2022] Open
Abstract
KEY POINTS Muscular dystrophy patients suffer from progressive degeneration of skeletal muscle fibres, sudden spontaneous falls, balance problems, as well as gait and posture abnormalities. Dystrophin- and dysferlin-deficient mice, models for different types of muscular dystrophy with different aetiology and molecular basis, were characterized to investigate if muscle spindle structure and function are impaired. The number and morphology of muscle spindles were unaltered in both dystrophic mouse lines but muscle spindle resting discharge and their responses to stretch were altered. In dystrophin-deficient muscle spindles, the expression of the paralogue utrophin was substantially upregulated, potentially compensating for the dystrophin deficiency. The results suggest that muscle spindles might contribute to the motor problems observed in patients with muscular dystrophy. ABSTRACT Muscular dystrophies comprise a heterogeneous group of hereditary diseases characterized by progressive degeneration of extrafusal muscle fibres as well as unstable gait and frequent falls. To investigate if muscle spindle function is impaired, we analysed their number, morphology and function in wildtype mice and in murine model systems for two distinct types of muscular dystrophy with very different disease aetiology, i.e. dystrophin- and dysferlin-deficient mice. The total number and the overall structure of muscle spindles in soleus muscles of both dystrophic mouse mutants appeared unchanged. Immunohistochemical analyses of wildtype muscle spindles revealed a concentration of dystrophin and β-dystroglycan in intrafusal fibres outside the region of contact with the sensory neuron. While utrophin was absent from the central part of intrafusal fibres of wildtype mice, it was substantially upregulated in dystrophin-deficient mice. Single-unit extracellular recordings of sensory afferents from muscle spindles of the extensor digitorum longus muscle revealed that muscle spindles from both dystrophic mouse strains have an increased resting discharge and a higher action potential firing rate during sinusoidal vibrations, particularly at low frequencies. The response to ramp-and-hold stretches appeared unaltered compared to the respective wildtype mice. We observed no exacerbated functional changes in dystrophin and dysferlin double mutant mice compared to the single mutant animals. These results show alterations in muscle spindle afferent responses in both dystrophic mouse lines, which might cause an increased muscle tone, and might contribute to the unstable gait and frequent falls observed in patients with muscular dystrophy.
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Affiliation(s)
- Laura Gerwin
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany.,Institute for Stem Cell Research, German Research Center for Environmental Health, Helmholtz Centre Munich, Ingolstädter Landstraße 1, D-85764, Neuherberg, Germany
| | - Sarah Rossmanith
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany
| | - Corinna Haupt
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany
| | - Jürgen Schultheiß
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany
| | - Heinrich Brinkmeier
- Institute for Pathophysiology, University Medicine Greifswald, Martin-Luther-Str. 6, 17489, Greifswald, Germany
| | - Reginald E Bittner
- Neuromuscular Research Department, Center for Anatomy and Cell Biology, Medical University of Vienna, Waehringerstrasse 13, 1090, Vienna, Austria
| | - Stephan Kröger
- Department of Physiological Genomics, Biomedical Center, Ludwig-Maximilians-University, Großhaderner Str. 9, D-82152, Planegg-Martinsried, Germany
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Fokin A, Minderis P, Venckunas T, Lionikas A, Kvedaras M, Ratkevicius A. Myostatin dysfunction does not protect from fasting-induced loss of muscle mass in mice. JOURNAL OF MUSCULOSKELETAL & NEURONAL INTERACTIONS 2019; 19:342-353. [PMID: 31475942 PMCID: PMC6737554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
OBJECTIVES The aim of the study was to investigate if myostatin dysfunction can ameliorate fasting-induced muscle wasting. METHODS 18-week old males from Berlin high (BEH) strain with myostatin dysfunction and wild type myostatin (BEH+/+) strain were subjected to 48-h food deprivation (FD). Changes in body composition as well as contractile properties of soleus (SOL) and extensor digitorum longus (EDL) muscles were studied. RESULTS BEH mice were heavier than BEH+/+ mice (56.0±2.5 vs. 49.9±2.8 g, P<0.001, respectively). FD induced similar loss of body mass in BEH and BEH+/+ mice (16.6±2.4 vs. 17.4±2.2%, P>0.05), but only BEH mice experienced wasting of the gastrocnemius, tibialis anterior and plantaris muscles. FD induced a marked decrease in specific muscle force of SOL. EDL of BEH mice tended to be protected from this decline. CONCLUSION Myostatin dysfunction does not protect from loss of muscle mass during fasting.
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Affiliation(s)
- Andrej Fokin
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Petras Minderis
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Tomas Venckunas
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania,Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Kaunas, Lithuania
| | - Arimantas Lionikas
- School of Medicine, Medical Sciences and Nutrition, College of Life Sciences and Medicine, University of Aberdeen, Aberdeen, Scotland, UK
| | - Mindaugas Kvedaras
- Institute of Sport Science and Innovations, Lithuanian Sports University, Kaunas, Lithuania
| | - Aivaras Ratkevicius
- Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Kaunas, Lithuania,Corresponding author: Dr. Aivaras Ratkevicius, Department of Applied Biology and Rehabilitation, Lithuanian Sports University, Sporto g. 6, LT-44221 Kaunas, Lithuania E-mail:
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7
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Zeller-Plumhoff B, Roose T, Katsamenis OL, Mavrogordato MN, Torrens C, Schneider P, Clough GF. Phase contrast synchrotron radiation computed tomography of muscle spindles in the mouse soleus muscle. J Anat 2017; 230:859-865. [PMID: 28369928 DOI: 10.1111/joa.12606] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/08/2017] [Indexed: 12/29/2022] Open
Abstract
Muscle spindles are skeletal muscle sensory organs involved in the sensation of position and movement of the body. We have explored the capability of phase contrast computed tomography to visualise muscle spindles in murine skeletal muscle. In particular, we have validated the visualisation of nerve fibres through phase contrast computed tomography using light microscopy on stained histological sections. We further present the first three-dimensional visualisation of muscle spindles in mouse soleus skeletal muscle in conjunction with the neurovascular bundle associated with it.
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Affiliation(s)
- B Zeller-Plumhoff
- Faculty of Engineering and the Environment, University of Southampton, Southampton, UK.,Helmholtz-Zentrum für Material- und Küstenforschung, Geesthacht, Germany
| | - T Roose
- Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - O L Katsamenis
- Faculty of Engineering and the Environment, University of Southampton, Southampton, UK.,μ-VIS X-ray Imaging Centre, University of Southampton, Southampton, UK
| | - M N Mavrogordato
- Faculty of Engineering and the Environment, University of Southampton, Southampton, UK.,μ-VIS X-ray Imaging Centre, University of Southampton, Southampton, UK
| | - C Torrens
- Faculty of Medicine, University of Southampton, Southampton, UK
| | - P Schneider
- Faculty of Engineering and the Environment, University of Southampton, Southampton, UK
| | - G F Clough
- Faculty of Medicine, University of Southampton, Southampton, UK
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Sonner MJ, Walters MC, Ladle DR. Analysis of Proprioceptive Sensory Innervation of the Mouse Soleus: A Whole-Mount Muscle Approach. PLoS One 2017; 12:e0170751. [PMID: 28122055 PMCID: PMC5266321 DOI: 10.1371/journal.pone.0170751] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 12/28/2016] [Indexed: 01/27/2023] Open
Abstract
Muscle proprioceptive afferents provide feedback critical for successful execution of motor tasks via specialized mechanoreceptors housed within skeletal muscles: muscle spindles, supplied by group Ia and group II afferents, and Golgi tendon organs, supplied by group Ib afferents. The morphology of these proprioceptors and their associated afferents has been studied extensively in the cat soleus, and to a lesser degree, in the rat; however, quantitative analyses of proprioceptive innervation in the mouse soleus are comparatively limited. The present study employed genetically-encoded fluorescent reporting systems to label and analyze muscle spindles, Golgi tendon organs, and the proprioceptive sensory neuron subpopulations supplying them within the intact mouse soleus muscle using high magnification confocal microscopy. Total proprioceptive receptors numbered 11.3 ± 0.4 and 5.2 ± 0.2 for muscle spindles and Golgi tendon organs, respectively, and these receptor counts varied independently (n = 27 muscles). Analogous to findings in the rat, muscle spindles analyzed were most frequently supplied by two proprioceptive afferents, and in the majority of instances, both were classified as primary endings using established morphological criteria. Secondary endings were most frequently observed when spindle associated afferents totaled three or more. The mean diameter of primary and secondary afferent axons differed significantly, but the distributions overlap more than previously observed in cat and rat studies.
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Affiliation(s)
- Martha J. Sonner
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio, United States of America
| | - Marie C. Walters
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio, United States of America
| | - David R. Ladle
- Department of Neuroscience, Cell Biology, and Physiology, Wright State University, Dayton, Ohio, United States of America
- * E-mail:
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Kilikevicius A, Bunger L, Lionikas A. Baseline Muscle Mass Is a Poor Predictor of Functional Overload-Induced Gain in the Mouse Model. Front Physiol 2016; 7:534. [PMID: 27895593 PMCID: PMC5108802 DOI: 10.3389/fphys.2016.00534] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2016] [Accepted: 10/26/2016] [Indexed: 12/15/2022] Open
Abstract
Genetic background contributes substantially to individual variability in muscle mass. Muscle hypertrophy in response to resistance training can also vary extensively. However, it is less clear if muscle mass at baseline is predictive of the hypertrophic response. The aim of this study was to examine the effect of genetic background on variability in muscle mass at baseline and in the adaptive response of the mouse fast- and slow-twitch muscles to overload. Males of eight laboratory mouse strains: C57BL/6J (B6, n = 17), BALB/cByJ (n = 7), DBA/2J (D2, n = 12), B6.A-(rs3676616-D10Utsw1)/Kjn (B6.A, n = 9), C57BL/6J-Chr10A/J/NaJ (B6.A10, n = 8), BEH+/+ (n = 11), BEH (n = 12), and DUHi (n = 12), were studied. Compensatory growth of soleus and plantaris muscles was triggered by a 4-week overload induced by synergist unilateral ablation. Muscle weight in the control leg (baseline) varied from 5.2 ± 07 mg soleus and 11.4 ± 1.3 mg plantaris in D2 mice to 18.0 ± 1.7 mg soleus in DUHi and 43.7 ± 2.6 mg plantaris in BEH (p < 0.001 for both muscles). In addition, soleus in the B6.A10 strain was ~40% larger (p < 0.001) compared to the B6. Functional overload increased muscle weight, however, the extent of gain was strain-dependent for both soleus (p < 0.01) and plantaris (p < 0.02) even after accounting for the baseline differences. For the soleus muscle, the BEH strain emerged as the least responsive, with a 1.3-fold increase, compared to a 1.7-fold gain in the most responsive D2 strain, and there was no difference in the gain between the B6.A10 and B6 strains. The BEH strain appeared the least responsive in the gain of plantaris as well, 1.3-fold, compared to ~1.5-fold gain in the remaining strains. We conclude that variation in muscle mass at baseline is not a reliable predictor of that in the overload-induced gain. This suggests that a different set of genes influence variability in muscle mass acquired in the process of normal development, growth, and maintenance, and in the process of adaptive growth of the muscle challenged by overload.
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Affiliation(s)
- Audrius Kilikevicius
- Institute of Sport Science and Innovations, Lithuanian Sports University Kaunas, Lithuania
| | - Lutz Bunger
- Animal & Veterinary Sciences, Scotland's Rural College, Roslin Institute Building Midlothian, UK
| | - Arimantas Lionikas
- School of Medicine, Medical Sciences and Nutrition, College of Life Sciences and Medicine, University of Aberdeen Aberdeen, UK
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Dong C, Zheng S. Immunohistochemical analysis of orbicularis oris muscle fiber distribution at the philtrum in healthy infants. Int J Pediatr Otorhinolaryngol 2015; 79:2208-12. [PMID: 26527071 DOI: 10.1016/j.ijporl.2015.10.005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 10/08/2015] [Accepted: 10/09/2015] [Indexed: 01/26/2023]
Abstract
OBJECTIVE To characterize the fiber-type distribution of the orbicularis oris muscle at the philtrum in healthy infants by immunohistochemistry and examine the relationship between orbicularis oris and philtrum structure. METHODS Samples of the upper lip were obtained from two infant cadavers. Serial sagittal sections were obtained at the midline of the philtral dimple, unilateral philtral ridge, and the lateral side. Three sections from each site were prepared for immunohistochemical staining using myosin heavy chain fast fiber (MHCf) and myosin heavy chain slow fiber (MHCs) antibodies to determine the ratio of fast to slow skeletal muscle fibers. RESULTS The ratio of fast to slow muscle fibers differed significantly among the superficial orbicularis oris muscle (98.30%:1.13%), deep pars peripheralis (95.30%:3.14%), and deep pars marginalis (91.31%:5.74%), with a significantly higher percentage of slow fibers in the pars marginalis compared to pars peripheralis (P=0.002) and fast fibers in the superficial muscle compared to pars marginalis and peripheralis (both P=0.000). Similarly, the fast:slow fiber ratio differed among the superficial philtral dimple (95.88%:2.41%), superficial philtral ridge (98.52%:1.11%), and superficial midlateral philtral ridge (99.07%:0.66%), with a higher percentage of fast fibers higher on the lateral side of the superficial philtral ridge than at the philtral ridge (P=0.030) and higher at the philtral ridge than the philtral dimple (P=0.001). The fast:slow fiber ratio did not differ within the pars peripheralis at the philtral dimple (93.94%:4.19%), philtral ridge (94.49%:3.84%), and lateral philtral ridge (95.79%:2.70%) (all P>0.05). CONCLUSIONS Philtum structure is likely determined in part by the distribution of muscle fiber types among philtral dimple, ridge, and lateral side. These differences should be considered in cleft lip repair.
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Affiliation(s)
- Chenbin Dong
- Department of Plastic Surgery, Children's Hospital of Fudan University, Shanghai 201102, China
| | - Shan Zheng
- Department of Plastic Surgery, Children's Hospital of Fudan University, Shanghai 201102, China.
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11
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Banks RW. The innervation of the muscle spindle: a personal history. J Anat 2015; 227:115-35. [PMID: 26095428 DOI: 10.1111/joa.12297] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2015] [Indexed: 11/27/2022] Open
Abstract
I present a brief review of current understanding of the innervation of the mammalian muscle spindle, from a personal historical perspective. The review begins with comparative studies on the numbers of spindle afferents and considers how their relative abundance may best be assessed. This is followed by an examination of the distribution and some functional properties of the motor innervation. The primary ending is the subject of the final section, in particular, I look at what can be learned from serial sectioning and volumetric reconstruction, and present new results on a model and simulations concerning sensory terminal deformation during stretch.
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Affiliation(s)
- Robert W Banks
- School of Biological and Biomedical Sciences, Durham University, Durham, UK
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12
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Carbonetto P, Cheng R, Gyekis JP, Parker CC, Blizard DA, Palmer AA, Lionikas A. Discovery and refinement of muscle weight QTLs in B6 × D2 advanced intercross mice. Physiol Genomics 2014; 46:571-82. [PMID: 24963006 DOI: 10.1152/physiolgenomics.00055.2014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The genes underlying variation in skeletal muscle mass are poorly understood. Although many quantitative trait loci (QTLs) have been mapped in crosses of mouse strains, the limited resolution inherent in these conventional studies has made it difficult to reliably pinpoint the causal genetic variants. The accumulated recombination events in an advanced intercross line (AIL), in which mice from two inbred strains are mated at random for several generations, can improve mapping resolution. We demonstrate these advancements in mapping QTLs for hindlimb muscle weights in an AIL (n = 832) of the C57BL/6J (B6) and DBA/2J (D2) strains, generations F8-F13. We mapped muscle weight QTLs using the high-density MegaMUGA SNP panel. The QTLs highlight the shared genetic architecture of four hindlimb muscles and suggest that the genetic contributions to muscle variation are substantially different in males and females, at least in the B6D2 lineage. Out of the 15 muscle weight QTLs identified in the AIL, nine overlapped the genomic regions discovered in an earlier B6D2 F2 intercross. Mapping resolution, however, was substantially improved in our study to a median QTL interval of 12.5 Mb. Subsequent sequence analysis of the QTL regions revealed 20 genes with nonsense or potentially damaging missense mutations. Further refinement of the muscle weight QTLs using additional functional information, such as gene expression differences between alleles, will be important for discerning the causal genes.
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Affiliation(s)
| | - R Cheng
- Australian National University, Canberra, Australia
| | - J P Gyekis
- Pennsylvania State University, State College, Pennsylvania; and
| | | | - D A Blizard
- Pennsylvania State University, State College, Pennsylvania; and
| | - A A Palmer
- University of Chicago, Chicago, Illinois
| | - A Lionikas
- University of Aberdeen, Aberdeen, United Kingdom;
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