Time course of changes in angiogenesis-related factors in denervated muscle.
OBJECTIVE
Denervation leads to capillary regression in skeletal muscle. To gain insight into the regulation of this process, we investigated the time course of changes in capillary supply and gene expression of angiogenesis-related factors during muscle denervation.


METHODS
Female mice underwent surgery to transect the sciatic nerve, and then the gastrocnemius muscles were isolated at 12 h, 1, 3, 5, 10, 20, or 30 days after surgery. The capillary supply was assessed by immunohistochemistry using anti-PECAM-1/CD31 antibody. The mRNA levels for angiogenesis-related factors were analysed using a real-time polymerase chain reaction.


RESULTS
We found that the capillary-to-fibre ratio began to decrease 10 days after muscle denervation and decreased by 52% after 30 days. The levels of mRNA for vascular endothelial growth factor (VEGF), its receptors [fms-like tyrosine kinase (Flt-1) and a kinase insert domain-containing receptor/fetal liver kinase-1 (KDR/Flk-1)], angiopoietin-1 and angiopoietin-2 of denervated muscle were immediately down-regulated after 12 h and remained lower than control muscle until 30 days after muscle denervation. The levels of mRNA for the VEGF receptor, neuropilin-1, angiopoietin receptor and Tie-2 decreased within 12-24 h, but returned to near those of control muscle after 10-20 days, and again decreased after 30 days.


CONCLUSIONS
These findings suggest that denervation-induced capillary regression may be associated with down-regulation of VEGF and angiopoietin signalling.
Wagatsuma
A
A
Department of Biochemical Sciences, National Institute of Fitness and Sports, Shiromizu, Kanoya, Kagoshima, Japan. waga@nifs-k.ac.jp
Osawa
T
T
D043925:Angiogenesis Inducing Agents / Q000378:metabolism*; D042682:Angiopoietins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002196:Capillaries / Q000473:pathology; D015536:Down-Regulation; D005260:Female; D051379:Mice; D008815:Mice, Inbred Strains; D009121:Muscle Denervation; D018482:Muscle, Skeletal / Q000098:blood supply / Q000294:innervation* / Q000378:metabolism; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000235:genetics; D013997:Time Factors; D046509:Tissue Culture Techniques; D042461:Vascular Endothelial Growth Factor A / Q000235:genetics / Q000378:metabolism
D043925:Angiogenesis Inducing Agents; D042682:Angiopoietins; D012333:RNA, Messenger; D042461:Vascular Endothelial Growth Factor A