17β‐Oestradiol inhibits doxorubicin‐induced apoptosis via block of the volume‐sensitive Cl^‐ current in rabbit articular chondrocytes

Abstract

BACKGROUND AND PURPOSEChondrocyte apoptosis contributes to disruption of cartilage integrity in osteoarthritis. Recent evidence suggested that the volume-sensitive organic osmolyte/anion channel [volume-sensitive (outwardly rectifying) Cl -current (ICl,vol)] plays a functional role in the development of cell shrinkage associated with apoptosis (apoptotic volume decrease) in several cell types. In this study, we investigated the cellular effects of 17b-oestradiol on doxorubicin-induced apoptotic responses in rabbit articular chondrocytes. EXPERIMENTAL APPROACHWhole-cell membrane currents and cross-sectional area were measured from chondrocytes using a patch-clamp method and microscopic cell imaging, respectively. Caspase-3/7 activity was assayed as an index of apoptosis. KEY RESULTSAddition of doxorubicin (1 mM) to isosmotic bath solution rapidly activated the Cl -current with properties similar to those of ICl,vol in chondrocytes. Doxorubicin also gradually decreased the cross-sectional area of chondrocytes, followed by enhanced caspase-3/7 activity; both of these responses were totally abolished by the ICl,vol blocker DCPIB (20 mM). Pretreatment of chondrocytes with 17b-oestradiol (1 nM) for short (approximately 10 min) and long (24 h) periods almost completely prevented the doxorubicin-induced activation of ICl,vol and subsequent elevation of caspase-3/7 activity. These effects of 17b-oestradiol were significantly attenuated by the oestrogen receptor blocker ICI 182780 (10 mM), as well as the phosphatidyl inositol-3-kinase (PI3K) inhibitors wortmannin (100 nM) and LY294002 (20 mM). Testosterone (10 nM) had no effect on the doxorubicin-induced Cl -current. CONCLUSIONS AND IMPLICATIONS17b-Oestradiol prevents the doxorubicin-induced cell shrinkage mediated through activation of ICl,vol and subsequent induction of apoptosis signals, through a membrane receptor-dependent PI3K pathway in rabbit articular chondrocytes. AbbreviationsAVD, apoptotic volume decrease; Cm, cell membrane capacitance; DCPIB, 4-(2-butyl-6,7-dichloro-2-cyclopentyl-indan-1-on-5-yl) oxybutyric

Astrocytes Prevent Ethanol Induced Apoptosis of Nrf2 Depleted Neurons by Maintaining GSH Homeostasis

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Cell Volume-Activated and Volume-Correlated Anion Channels in Mammalian Cells: Their Biophysical, Molecular, and Pharmacological Properties

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Comparative Histological Study between the Effect of Calcitonin versus Hormonal Replacement Therapy on Cartilage of Knee Joint of Ovariectomized Albino Rat

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