Wijerathne Tharaka Darshana, Kim Ji Hyun, Kim Min Ji, Kim Chul Young, Chae Mee Ree, Lee Sung Won, Lee Kyu Pil
Department of Physiology, College of Veterinary Medicine, Chungnam National University, Daejeon 34134, Korea.
College of Pharmacy, Hanyang University, Ansan 15588, Korea.
Korean J Physiol Pharmacol. 2019 Sep;23(5):381-392. doi: 10.4196/kjpp.2019.23.5.381. Epub 2019 Aug 26.
Sperm function and male fertility are closely related to pH dependent K current (KSper) in human sperm, which is most likely composed of Slo3 and its auxiliary subunit leucine-rich repeat-containing protein 52 (LRRC52). Onion peel extract (OPE) and its major active ingredient quercetin are widely used as fertility enhancers; however, the effect of OPE and quercetin on Slo3 has not been elucidated. The purpose of this study is to investigate the effect of quercetin on human Slo3 channels. Human Slo3 and LRRC52 were co-transfected into HEK293 cells and pharmacological properties were studied with the whole cell patch clamp technique. We successfully expressed and measured pH sensitive and calcium insensitive Slo3 currents in HEK293 cells. We found that OPE and its key ingredient quercetin inhibit Slo3 currents. Inhibition by quercetin is dose dependent and this degree of inhibition decreases with elevating internal alkalization and internal free calcium concentrations. Functional moieties in the quercetin polyphenolic ring govern the degree of inhibition of Slo3 by quercetin, and the composition of such functional moieties are sensitive to the pH of the medium. These results suggest that quercetin inhibits Slo3 in a pH and calcium dependent manner. Therefore, we surmise that quercetin induced depolarization in spermatozoa may enhance the voltage gated proton channel (Hv1), and activate non-selective cation channels of sperm (CatSper) dependent calcium influx to trigger sperm capacitation and acrosome reaction.
精子功能和男性生育能力与人类精子中pH依赖性钾电流（KSper）密切相关，该电流很可能由Slo3及其辅助亚基富含亮氨酸重复序列的蛋白52（LRRC52）组成。洋葱皮提取物（OPE）及其主要活性成分槲皮素被广泛用作生育增强剂；然而，OPE和槲皮素对Slo3的作用尚未阐明。本研究的目的是探讨槲皮素对人类Slo3通道的影响。将人类Slo3和LRRC52共转染到HEK293细胞中，并用全细胞膜片钳技术研究其药理特性。我们成功地在HEK293细胞中表达并测量了对pH敏感且对钙不敏感的Slo3电流。我们发现OPE及其关键成分槲皮素抑制Slo3电流。槲皮素的抑制作用呈剂量依赖性，且这种抑制程度随着细胞内碱化和细胞内游离钙浓度的升高而降低。槲皮素多酚环中的功能基团决定了槲皮素对Slo3的抑制程度，且这些功能基团的组成对培养基的pH敏感。这些结果表明，槲皮素以pH和钙依赖性方式抑制Slo3。因此，我们推测槲皮素诱导的精子去极化可能增强电压门控质子通道（Hv1），并激活依赖于精子非选择性阳离子通道（CatSper）的钙内流，从而触发精子获能和顶体反应。
