Tohoku J. Exp. Med., 2016 April, 238(4)

Lead Inhibits Human Sperm Functions by Reducing the Levels of Intracellular Calcium, cAMP, and Tyrosine Phosphorylation

YUANQIAO HE,^1,2 QIANXING ZOU,¹ HOUYANG CHEN,³ SHIQI WENG,¹ TAO LUO¹ and XUHUI ZENG¹

¹Institute of Life Science, Nanchang University, Nanchang, Jiangxi, P.R. China
²Department of Laboratory Animal Science, Nanchang University, Nanchang, Jiangxi, P.R. China
³Reproductive Medical Center, Jiangxi Provincial Maternal and Child Health Hospital, Nanchang, Jiangxi, P.R. China

It is well known that there has been a worldwide decrease in human male fertility in recent years. One of the main factors affecting this is environmental pollution. Lead is one of the major heavy metal contaminants that threaten the health of animals and human beings in China. It preferentially accumulates in male reproductive organs and can be up to 10 μM in human seminal plasma. Lead impairs mammalian spermatogenesis and sperm quality in vivo. It also inhibits sperm functions in vitro but the underlying mechanisms remain unclear. Therefore, we aimed to investigate the in vitro toxicity of lead on human sperm functions and to elucidate the underlying mechanisms. Semen samples were collected from 20 healthy volunteers with different careers and backgrounds living in Nanchang, Jiangxi. Human sperm suspensions were treated with different concentrations of lead acetate (0, 0.5, 2.5, 10, 50, and 100 μM) and the viability, motility, capacitation and progesterone-induced acrosome reaction were examined. Treatment with 10-100 μM lead acetate dose-dependently inhibited total and progressive motility measures, capacitation and progesterone-induced acrosome reaction. It also dose-dependently decreased the intracellular concentrations of cyclic adenosine monophosphate (cAMP) and calcium ([Ca²⁺]_i), and reduced the tyrosine phosphorylation of sperm proteins, all of which are thought to be key factors in the regulation of sperm function. Our findings suggest that lead inhibits human sperm functions by reducing the levels of sperm intracellular cAMP, [Ca²⁺]_i and tyrosine phosphorylation of sperm proteins in vitro.

keywords —— [Ca²⁺]_i; cyclic adenosine monophosphate; human sperm function; lead acetate; protein-tyrosine phosphorylation

© 2016 Tohoku University Medical Press

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Tohoku J. Exp. Med., 2016, 238, 295-303

Correspondence: Xuhui Zeng, Institute of Life Science, Nanchang University, No.999, Xuefu Road, Nanchang, Jiangxi 330031, P.R. China.

e-mail: xuhuizeng@hotmail.com

Tao Luo, Institute of Life Science, Nanchang University, No.999, Xuefu Road, Nanchang, Jiangxi 330031, P.R. China.

e-mail: luotao@ncu.edu.cn