Journal of Pain Research (Apr 2021)
Estrogen Regulation of the Expression of Pain Factor NGF in Rat Chondrocytes
Abstract
Xiushuai Shang,1,2 Liaoran Zhang,2 Rilong Jin,1 Hu Yang,1 Hairong Tao2 1Department of Orthopedics Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, People’s Republic of China; 2Shanghai Key Laboratory of Orthopaedic Implant, Department of Orthopaedic Surgery, Shanghai Ninth People’s Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, People’s Republic of ChinaCorrespondence: Hairong TaoShanghai Key Laboratory of Orthopaedic Implants, Department of Orthopaedic Surgery, Shanghai Ninth People’s Hospital, Shanghai JiaoTong University School of Medicine, No. 639 Zhizaoju Road, Shanghai, 200011, People’s Republic of ChinaTel +86-13761221256Email [email protected]: Pain is the main symptom of osteoarthritis (OA). Nerve growth factor (NGF) plays a crucial role in the generation of OA pain. And estrogen-alone used resulted in a sustained joint pain reduction in postmenopausal women. So we aim to find whether estrogen alters chondrocytes’ NGF level, affecting OA pain.Methods: Primary chondrocytes and cartilage explants isolated from Sprague Dawley rat knees were cultured with physiological concentrations of estrogen (17β-Estradiol ≥ 98%, E2), Estrogen Receptor α (ERα) inhibitor and stimulants. Then, chondrocytes NGF mRNA expression and protein release were analyzed by a quantitative real-time polymerase chain reaction (qPCR) and enzyme-linked immunosorbent assay (ELISA) respectively. Additionally, cultures were pre-incubated with MEK-ERK inhibitor to identify the signaling pathway that estrogen alters NGF mRNA and protein levels.Results: We found that chondrocytes NGF expression and release were decreased by E2. E2 also reduced chondrocytes IL-1β-stimulated or TGF-β 1-stimulated NGF expression. Phosphorylated extracellular signal-regulated kinasep1/2 (p-ERK1/2) signals were detected stronger than the control group by Western Blotting (WB). When we cultured chondrocytes with PD98059 (MEK-ERK inhibitor, PD), NGF mRNA expression was added to 1.41Ct (2.07± 0.1 fold).Conclusion: We showed that E2 reduces chondrocytes NGF expression significantly, even after stimulation by TGF-β 1 or IL-1β. MEK-ERK signaling is involved in this process.Keywords: osteoarthritis, pain, estrogens, nerve growth factor
