Becher et al. Journal of Orthopaedic Surgery and Research 2010, 5:28 RESEARCH ARTICLE Research article Open Access Decrease in the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes in animals with osteoarthritis Christoph Becher1, Thomas Szuwart2, Philipp Ronstedt2, Sven Ostermeier1, Adrian Skwara3, Susanne FuchsWinkelmann3 and Carsten O Tibesku*4 Abstract Background: To evaluate the expression of the type 1 PTH/PTHrP receptor (PTH1R) on chondrocytes from hyaline cartilage over the course of osteoarthritis (OA). Methods: In 12 NZW rabbits, the anterior cruciate ligament (ACL) was resected to create anterior instability of the knee. In 12 control rabbits, only a sham operation, without resection of the. | Becher et al. Journal of Orthopaedic Surgery and Research 2010 5 28 http content 5 1 28 éHMÌ JOURNAL OF ORTHOPAEDIC MBs SURGERY AND RESEARCH RESEARCH ARTICLE Open Access Decrease in the expression of the type 1 PTH PTHrP receptor PTH1R on chondrocytes in animals with osteoarthritis Christoph Becher1 Thomas Szuwart2 Philipp Ronstedt2 Sven Ostermeier1 Adrian Skwara3 Susanne Fuchs-Winkelmann3 and Carsten OTibesku 4 Abstract Background To evaluate the expression of the type 1 PTH PTHrP receptor PTH1R on chondrocytes from hyaline cartilage over the course of osteoarthritis OA . Methods In 12 NZW rabbits the anterior cruciate ligament ACL was resected to create anterior instability of the knee. In 12 control rabbits only a sham operation without resection of the ACL was performed. Four animals from each group were killed at 3 6 and 12 weeks. After opening the knee joint OA was macroscopically graded and hyaline cartilage of the load-bearing area was evaluated histologically according to the Mankin scale and by immunostaining for PTH1R. Results There was a positive linear correlation between the time after surgery and the macroscopic and histologic OA scores. The scores in the control group were constant over the time course. Immunostaining showed significantly less expression of PTH1R in the experimental compared to the control group after 6 P and 12 weeks P . In the experimental group a negative linear correlation between PTH1R expression and macroscopic and histologic grades was found. Conclusions The results show an in vivo decrease in the expression of PTH1R on chondrocytes over the time course of OA. Further studies are needed to evaluate whether new treatment approaches could evolve from this knowledge. Introduction The type 1 PTH PTHrP receptor PTH1R belongs to a family of G-protein-coupled receptors GPCR with seven membrane-spanning helixes 1 . The PTH1R acts as a common receptor for the Parathyroid hormone PTH and the Parathyroid .
