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Tail Suspension (tail + suspension)

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Medical Sciences75%

Terms modified by Tail Suspension

  • tail suspension test
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    Selected Abstracts

    Skeletal muscle HSP72 response to mechanical unloading: influence of endurance training

    ACTA PHYSIOLOGICA, Issue 4 2004
    D. Desplanches
    Abstract Aims:, It has been shown that increased contractile activity results in heat shock protein 72 (HSP72) accumulation in various skeletal muscles. By contrast, there is no consensus for muscle HSP72 response to muscle disuse for short duration (5,8 days). On the basis of a greater constitutive HSP72 expression in slow-twitch muscles we tested the hypothesis that mechanical unloading for a longer period (2 weeks) would affect this phenotype to a greater extent. Secondly, we evaluated the effects of a physiological muscle heat shock protein (HSP) enhancer (endurance training) on HSP response to unloading and muscle remodelling. Methods:, Adult male Wistar rats were assigned randomly to four groups: (1) sedentary weight-bearing; (2) hindlimb-unloaded (HU) via tail suspension for 2 week; (3) trained on a treadmill (6 week) and (4) trained 6 week and then HU for 2 week. Results:, Unloading resulted in a preferential atrophy of slow muscles [soleus (SOL), adductor longus (AL)] and a slow-to-fast fibre transition with no change in HSP72 level. HSP72 levels were significantly lower in fast muscles [extensor digitorum longus (EDL) and plantaris (PLA)], and did not change with mechanical unloading. Endurance training was accompanied by a small (SOL) or a large (EDL, PLA) increase in HSP72 level with no change in AL. Training-induced accumulation of HSP72 disappeared with subsequent unloading in the SOL and PLA whereas HSP72 content remained elevated in EDL. Conclusion:, The results of this study indicate that (1) after 2 weeks of unloading no change occurred in HSP72 protein levels of slow-twitch muscles despite a slow-to-fast fibre transition; and (2) the training-induced increase of HSP72 content in skeletal muscles did not attenuate fibre transition. [source]

    Regional Alterations of Type I Collagen in Rat Tibia Induced by Skeletal Unloading,

    JOURNAL OF BONE AND MINERAL RESEARCH, Issue 9 2002
    Masashi Shiiba
    Abstract Skeletal unloading induces loss of mineral density in weight-bearing bones that leads to inferior bone mechanical strength. This appears to be caused by a failure of bone formation; however, its mechanisms still are not well understood. The objective of this study was to characterize collagen, the predominant matrix protein in bone, in various regions of tibia of rats that were subjected to skeletal unloading by 4 weeks tail suspension. Sixteen male Sprague-Dawley rats (4 months old) were divided into tail suspension and ambulatory controls (eight rats each). After the tail suspension, tibias from each animal were collected and divided into five regions and collagen was analyzed. The collagen cross-linking and the extent of lysine (Lys) hydroxylation in unloaded bones were significantly altered in proximal epiphysis, diaphysis, and, in particular, proximal metaphysis but not in distal regions. The pool of immature/nonmineralized collagen measured by its extractability with a chaotropic solvent was significantly increased in proximal metaphysis. These results suggest that skeletal unloading induced an accumulation of post-translationally altered nonmineralized collagen and that these changes are bone region specific. These alterations might be caused by impaired osteoblastic function/differentiation resulting in a mineralization defect. [source]

    Role of Inducible Nitric Oxide Synthase in Skeletal Adaptation to Acute Increases in Mechanical Loading,,

    JOURNAL OF BONE AND MINERAL RESEARCH, Issue 6 2002
    Makoto Watanuki M.D.
    Abstract To clarify the role of nitric oxide (NO) in regulation of bone metabolism in response to skeletal loading, we examined inducible NO synthase (iNOS) gene knockout mice in the tail-suspension model. Histomorphometric analyses of proximal tibias revealed that 7 days of tail suspension decreased the bone volume (BV/TV) and bone formation rate (BFR/BS) and increased the osteoclast surface (Oc.S/BS) in mice with all iNOS genotypes. Both iNOS+/+ and iNOS+/, mice responded to subsequent 14-day reloading, with increases in BV/TV and BFR/BS and a decrease in Oc.S/BS, whereas these responses were abolished in iNOS,/, mice. The osteoblasts flattened after tail suspension appeared cuboidal during subsequent reloading. Immunoreactivity for iNOS was detected in these osteoblasts and osteocytes by immunohistochemistry. These defective responses after reloading were rescued in iNOS,/, mice by treatment with an NO donor nitroglycerine (NG). Conversely, the responses in iNOS+/+ mice were inhibited by treatment with an NOS inhibitor aminoguanidine (AG). In bone marrow cell cultures, mineralized nodules derived from iNOS,/, mice after reloading were significantly reduced. Taken together, our results suggest that NO generated by iNOS in osteoblasts plays a critical role in adjusting bone turnover and increasing osteogenic activity in response to the acute increase in mechanical loading after tail suspension. [source]

    Antidepressant evaluation of polysaccharides from a Chinese herbal medicine Banxia-houpu decoction

    PHYTOTHERAPY RESEARCH, Issue 3 2004
    Yusong Guo
    Abstract Banxia-houpu decoction, a traditional Chinese medicine has been used in the treatment of depression. The present study con,rmed that oral administration of polysaccharides from Banxia-houpu decoction, exhibited a reduction in the immobility time in the tail suspension and in the forced swimming tests in mice in a time-dependent manner. This effect at a dose of 320 mg/kg was more potent than that at a dose of 640 mg/kg. The polysaccharides from Banxia-houpu decoction were active in animal models of depression with comparable effects to known antidepressants. The oral administration of the polysaccharides at a low dose for 4 weeks resulted in a signi,cant increase in the monoamine neurotransmitter 5-hydroxytryptamine (5-HT) and dopamine (DA) levels in whole mouse brain, but produced no signi,cant increase in 5-hydroxyindoleacetic acid (5-HIAA) and norepinephrine (NE) concentrations. The effect of polysaccharides on the brain neurotransmitter levels appeared to be quite different from the effect of ,uoxetine, a serotonin speci,c reuptake inhibitor. The results indicate that the mode of action of polysaccharides from Banxia-houpu decoction in depression might be related to both 5-HT and DA systems. Copyright © 2004 John Wiley & Sons, Ltd. [source]