Lecture 5 - Motor Mechanism

Science 2003 3021575 63 muscle regenera4on and age

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: eight and had drama4c shid to slow ­ oxida4ve muscle fibers –  Switch in fiber type does not require exercise per se 52 Skeletal muscle gene4cs 53 Skeletal muscle and age •  What happens to muscle as we age? 54 Skeletal muscle and age 55 Muscle  ­ Regenera4on Three steps for muscle regenera4on: 1.  The inflammatory reac4on, dominated by the invasion of macrophages 2.  The ac4va4on differen4a4on and fusion of satellite cells 3.  The matura4on of newly formed myofibrils and remodeling of regenerated muscle Current Pharmaceu4cal Design, 2010, Vol. 16, No. 8 56 Muscle  ­ Regenera4on •  Following the strain, ruptured myofibers contract and the gap is filled by a hematoma, which is invaded first by macrophages then by fibroblasts, which produce collagen and form scar 4ssue •  Satellite cell ac4va4on, prolifera4on and fusion take place Current Pharmaceu4cal Design, 2010, Vol. 16, No. 8 57 Muscle  ­ Regenera4on •  Instead of the rapid forma4on of new muscle fibers following a necro4c injury aged muscle responds with a delayed and only par4ally effec4ve myogenic response •  This will leave a fibrous scar where normal muscle would have formed in a younger individual Current Pharmaceu4cal Design, 2010, Vol. 16, No. 8 58 Muscle – Regenera4on and age What happens to muscle regeneraLon with age? •  Regenera4on of skeletal muscle decreases with age •  Scien4st performed a parabiosis experiment. They linked two mouse such that they only shared the circulatory system 59 Muscle – Regenera4on and age Snoeck (2005) Nature Biotechnol 23: 434 ­435 60 Muscle – Regenera4on and age •  The regenera4on of aged muscle was markedly improved when an old mouse was paired with a young mouse (“heterochronic” parabiosis) but not with another old mouse (“isochronic” parabiosis) •  Observed an increase in satellite cell ac4va4on and genera4on of myoblasts following injury •  Increased expression of the Notch ligand Delta. 61 Muscle – Regenera4on and age •  The improved regenera4on of the aged muscle was due to the enhanced ac4va4on of the aged, resident satellite cells and not to any contribu4on from circula4ng cells from the young pair –  determined by pairing GFP+...
View Full Document

Ask a homework question - tutors are online