Recombinant equine growth hormone administration: effects on synovial fluid biomarkers and cartilage metabolism in horses.
BACKGROUND
Recombinant equine growth hormone (reGH) has recently been evaluated for effects on body condition and wound healing. It has the potential to influence articular cartilage via stimulation of IGF-1.


OBJECTIVE
To investigate effects of administration on synovial joint metabolism.


METHODS
Six mature horses were given 20 microg/kg bwt reGH daily for 8 weeks by i.m. injection. Three control horses were injected with sterile water. Serum and synovial fluid samples were collected at 6, 8, 11 and 16 weeks for GH and IGF-1 assays. Articular cartilage harvested at week 16 was evaluated by Western analysis using monoclonal antibodies BC-13, BC-4, 8-A-4 and CH-3.


RESULTS
Concentrations of IGF-1 in serum and synovial fluid were significantly elevated (P < 0.05) at 6 and 8 weeks in the reGH group. Glycosaminoglycan concentrations in synovial fluid were significantly less than controls at these time points, suggesting that reGH may modulate proteoglycan metabolism in articular cartilage. In the reGH group, there were not any alterations in synovial fluid content of 3B3(-) epitope or aggrecan metabolite, or in aggrecan or link protein catabolites retained within cartilage, that might be expected with development of osteoarthritis.


CONCLUSIONS
Intramuscular administration of reGH may be a more efficient means of delivery of IGF-1 to joints for cartilage resurfacing initiatives.


CONCLUSIONS
We found no alterations in cartilage metabolism indicative of development of osteoarthritis.
Dart
A J
AJ
Department of Veterinary Clinical Sciences, University of Sydney, Sydney, Australia.
Little
C B
CB
Hughes
C E
CE
Chu
O
O
Dowling
B A
BA
Hodgson
D R
DR
Rose
R J
RJ
Johnson
K A
KA
D000818:Animals; D015415:Biomarkers / Q000032:analysis; D002358:Cartilage, Articular / Q000187:drug effects* / Q000378:metabolism; D000939:Epitopes / Q000378:metabolism; D006025:Glycosaminoglycans / Q000378:metabolism; D013006:Growth Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D006736:Horses / Q000378:metabolism*; D007273:Injections, Intramuscular / Q000662:veterinary; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000494:pharmacology; D013582:Synovial Fluid / Q000187:drug effects / Q000378:metabolism*
D015415:Biomarkers; D000939:Epitopes; D006025:Glycosaminoglycans; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone