title: Androgen receptors in muscle fibers induce rapid loss of force but not mass: implications for spinal bulbar muscular atrophy.
abstract: BACKGROUND
  Testosterone (T) induces motor dysfunction in transgenic (Tg) mice that overexpress wild-type androgen receptor (AR) in skeletal muscles. Because many genes implicated in motor neuron disease are expressed in skeletal muscle, mutant proteins may act in muscle to cause dysfunction in motor neuron disease.
  
  
  METHODS
  We examined contractile properties of the extensor digitorum longus (EDL) and soleus (SOL) muscles in vitro after 5 and 3 days of T treatment in motor-impaired Tg female mice.
  
  
  RESULTS
  Both muscles showed deficits in tetanic force after 5 days of T treatment, without losses in muscle mass, protein content, or fiber number. After 3 days of T treatment, only SOL showed a deficit in tetanic force comparable to that of 5 days of treatment. In both treatments, EDL showed slowed twitch kinetics, whereas SOL showed deficits in the twitch/tetanus ratio.
  
  
  CONCLUSIONS
  These results suggest calcium-handling mechanisms in muscle fibers are defective in motor-impaired mice.
authors: Neuroscience Program, Michigan State University, 108 Giltner Hall, 293 Farm Lane, East Lansing, Michigan 48824-1101, USA.
authors: Kentaro
authors: K
authors: Oki
authors: Robert W
authors: RW
authors: Wiseman
authors: S Marc
authors: SM
authors: Breedlove
authors: Cynthia L
authors: CL
authors: Jordan
mesh_terms: D000728:Androgens / Q000494:pharmacology*; D000818:Animals; D055534:Bulbo-Spinal Atrophy, X-Linked / Q000503:physiopathology*; D004195:Disease Models, Animal; D005260:Female; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009119:Muscle Contraction / Q000187:drug effects*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000473:pathology; D053580:Muscle Strength / Q000187:drug effects*; D009929:Organ Size / Q000187:drug effects; D051381:Rats; D011944:Receptors, Androgen / Q000235:genetics*; D013739:Testosterone / Q000494:pharmacology*
chemical_list: D000728:Androgens; D011944:Receptors, Androgen; D013739:Testosterone
references: J Endocrinol. 2011 Jul;210(1):93-104
references: 21555343
references: Proc Natl Acad Sci U S A. 2008 Feb 12;105(6):2198-202
references: 18268335
references: Lancet. 1995 Mar 18;345(8951):694-5
references: 7741893
references: J Clin Endocrinol Metab. 2004 Oct;89(10):5245-55
references: 15472231
references: Endocrinology. 2010 Jul;151(7):3125-32
references: 20427479
references: Neuron. 2004 Mar 4;41(5):687-99
references: 15003169
references: J Neurol Neurosurg Psychiatry. 2008 Jan;79(1):106-7
references: 17056629
references: Am J Physiol Cell Physiol. 2005 Apr;288(4):C824-30
references: 15574487
references: Nat Med. 2007 Mar;13(3):348-53
references: 17334372
references: J Inherit Metab Dis. 1997 Jun;20(2):152-8
references: 9211187
references: Am J Physiol. 1999 Sep;277(3):R917-21
references: 10484512
references: J Comp Neurol. 2004 May 17;473(1):59-72
references: 15067718
references: J Appl Physiol (1985). 2007 Jul;103(1):359-68
references: 17412789
references: Nature. 1991 Jul 4;352(6330):77-9
references: 2062380
references: Cell Metab. 2011 Aug 3;14(2):196-207
references: 21803290
references: Ann Neurol. 2009 Feb;65(2):140-50
references: 19259967
references: J Physiol. 2008 Jul 15;586(14):3337-51
references: 18467368
references: PLoS One. 2009;4(4):e5390
references: 19404401
references: Neuron. 2010 Sep 23;67(6):936-52
references: 20869592
references: J Neurosci. 2004 May 19;24(20):4778-86
references: 15152038
references: J Comp Neurol. 2012 Aug 1;520(11):2531-44
references: 22581688
references: Proc Natl Acad Sci U S A. 2007 Nov 13;104(46):18259-64
references: 17984063
references: Nat Med. 2009 Mar;15(3):325-30
references: 19198614
references: Neuron. 2002 Aug 29;35(5):843-54
references: 12372280
references: Nat Neurosci. 2007 May;10(5):608-14
references: 17435754
references: J Neurosci. 2006 Aug 23;26(34):8774-86
references: 16928866
references: J Gen Physiol. 1982 Jan;79(1):147-66
references: 7061985
references: J Clin Invest. 2006 Oct;116(10):2663-72
references: 16981011
references: Neurodegener Dis. 2011;8(1-2):25-34
references: 20689246
references: Am J Physiol. 1996 Sep;271(3 Pt 1):C878-86
references: 8843718
references: Muscle Nerve. 2009 Jul;40(1):126-9
references: 19533663
references: Proc Natl Acad Sci U S A. 1992 Aug 15;89(16):7521-5
references: 1502163
references: Neuromuscul Disord. 2000 Aug;10(6):391-7
references: 10899444
references: Nat Neurosci. 2007 May;10(5):615-22
references: 17435755
references: Physiol Rev. 2000 Jul;80(3):1215-65
references: 10893434
references: Neurobiol Dis. 2009 Apr;34(1):113-20
references: 19211034
references: J Neuroendocrinol. 2007 Oct;19(10):823-6
references: 17850465
references: Hum Mol Genet. 2010 Jun 1;19(11):2284-302
references: 20223753
references: Neuromuscul Disord. 2005 May;15(5):377-88
references: 15833433
references: J Neurol Neurosurg Psychiatry. 1964 Apr;27:96-9
references: 14167093
references: Neurology. 2002 Sep 10;59(5):770-2
references: 12221177
references: J Cell Biol. 2001 Mar 5;152(5):1107-14
references: 11238465
references: Horm Behav. 2008 Nov;54(5):758-66
references: 18775430