Aging impairs collateral sprouting of nociceptive axons in the rat.
Sprouting of uninjured nociceptive axons was examined in young adult, middle aged and aged rats. Axon sprouting from the spared sural nerve, both into adjacent denervated skin and into end-to-side coapted nerve graft, was significantly higher in young rats than in aged rats. Cross-transplantations of the end-to-side coapted nerve grafts between young and aged rats demonstrated that axon sprouting from young recipient nerves into aged donor nerve grafts was significantly deteriorated, whereas the axon sprouting from aged recipient nerves into young donor nerve grafts was not statistically significantly affected. The levels of laminin polypeptides in peripheral nerves were 50-100% higher in young adult than in aged rats. However, the levels of peripherin, NGF isoforms and TrkA in skin, peripheral nerves and DRG, respectively, were not significantly reduced in aged rats. Therefore, impaired sprouting of nociceptive axons in aged rats is due rather to the alterations in peripheral neural pathways, than to the limited sprouting capacity of aged sensory neurons. Decreased levels of extracellular matrix components might be important in this respect.
Kovacic
Uros
U
Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Zaloska 4, SI-1000 Ljubljana, Slovenia. uros.kovacic@mf.uni-lj.si
Zele
Tilen
T
Mars
Tomaz
T
Sketelj
Janez
J
Bajrović
Fajko F
FF
D000375:Aging / Q000502:physiology*; D000818:Animals; D001369:Axons / Q000502:physiology*; D005727:Ganglia, Spinal / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000378:metabolism; D007797:Laminin / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D009413:Nerve Fibers, Myelinated / Q000502:physiology; D020932:Nerve Growth Factor / Q000378:metabolism; D009416:Nerve Regeneration / Q000502:physiology*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D009434:Neural Pathways / Q000502:physiology; D009619:Nociceptors / Q000166:cytology / Q000502:physiology*; D010146:Pain / Q000503:physiopathology / Q000601:surgery; D010525:Peripheral Nerves / Q000502:physiology / Q000637:transplantation; D064531:Peripherins; D020033:Protein Isoforms / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D020917:Receptor, trkA / Q000378:metabolism; D020127:Recovery of Function / Q000502:physiology; D012867:Skin / Q000294:innervation / Q000378:metabolism; D013497:Sural Nerve / Q000166:cytology / Q000502:physiology*
D007381:Intermediate Filament Proteins; D007797:Laminin; D008562:Membrane Glycoproteins; D009419:Nerve Tissue Proteins; D064531:Peripherins; D020033:Protein Isoforms; D020932:Nerve Growth Factor; D020917:Receptor, trkA