Ultrastructural immunolocalization of cartilage oligomeric matrix protein, thrombospondin-4, and collagen fibril size in rodent achilles tendon in relation to exercise.
Fourteen 3-week-old Sprague-Dawley rats were housed in pairs in standard cages (5 controls) and in individual cages with a running wheel. Four of these rats had run 27-36 km/week (low training - LT) and 5 had run 56-92 km/week (high training - HT). After 4 weeks, the rats were euthanized and Achilles tendons were fixed for electron microscopy. The ultrastructural distribution of cartilage oligomeric matrix protein (COMP) and thrombospondin (TSP)-4 and collagen fibril thickness in two different extracellular compartments were studied. The immunolabeling of COMP decreased with longer running distance and was significantly lower in both the pericellular (p = 0.009) and interterritorial (p = 0.03) compartments of the HT rats compared with the controls. TSP-4 immunolabeling was higher in the pericellular compared with the interterritorial compartments in all rats (p = 0.013) but was not correlated with COMP immunolabeling. No alterations in collagen fibril size were found in relation to running; however, the gold markers representing COMP and TSP-4 were mostly found at the dark bands, representing the gap region of the fibril.
Södersten
Fredrik
F
Department of Biomedicine & Veterinary Public Health, Division of Pathology, Pharmacology and Toxicology, Swedish University of Agricultural Sciences, Uppsala, Sweden. fredrik.sodersten@bvf.slu.se
Ekman
Stina
S
Niehoff
Anja
A
Zaucke
Frank
F
Heinegård
Dick
D
Hultenby
Kjell
K
D000125:Achilles Tendon / Q000737:chemistry* / Q000648:ultrastructure; D000818:Animals; D002356:Cartilage; D003094:Collagen / Q000648:ultrastructure*; D016326:Extracellular Matrix Proteins / Q000032:analysis*; D006023:Glycoproteins / Q000032:analysis*; D064235:Matrilin Proteins; D008854:Microscopy, Electron; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D019699:Thrombospondins / Q000032:analysis*
D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D064235:Matrilin Proteins; D019699:Thrombospondins; C101864:thrombospondin 4; D003094:Collagen