Nerve Growth Factor and its association to osteoarthritis in the horseKendall, Anna
Osteoarthritis is common in horses and is a cause of pain and compromised welfare. Osteoarthritis-associated pain in horses is currently diagnosed by subjective and objective measurements of joint pain; however, there is a need to develop methods for evaluation of the systemic osteoarthritic pain that has been recognised in other species. Nerve growth factor (NGF) is associated with pain and osteoarthritis in humans, dogs, cats and lab animals but little is known about NGF in the horse.
The aim of this thesis was to determine the presence of NGF in the equine joint and circulation, and to investigate its connection to osteoarthritis-associated lameness. Serum and synovial fluid from lame horses with osteoarthritis were analysed by ELISA, and NGF levels were compared to those in sound horses. Cartilage and synovial membranes from osteoarthritic and healthy joints were analysed by immunohistochemistry for NGF and for the NGF receptors (TrkA and p75NTR). Chondrocyte lysates obtained from healthy and osteoarthritic cartilage were analysed by western blot and capillary simple western.
On a group level, serum NGF was higher in horses with osteoarthritis-associated lameness than in sound horses. Joints with acute or chronic inflammation had higher mean synovial fluid NGF than healthy joints and the expression of NGF and NGF receptors was increased in osteoarthritic articular cartilage compared to healthy articular cartilage. NGF receptor expression in osteoarthritic synovial membranes was also increased with marked individual variation in the relative TrkA/p75NTR expression. Two NGF precursor forms, 40 and 45 kDa, could be identified in equine articular chondrocytes and these forms did not appear to change with inflammation.
The results show that NGF is associated with osteoarthritis in the horse, in line with the findings in other species. The correlation between NGF and pain, individual variations in NGF receptor expression and the role of different precursor forms of NGF warrants further investigation.
KeywordsNerve Growth Factor; osteoarthritis; pain; horse
Published inActa Universitatis Agriculturae Sueciae
2023, number: 2023:4
ISBN: 978-91-8046-060-6, eISBN: 978-91-8046-061-3
Publisher: Swedish University of Agricultural Sciences
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