Rosmarinic acid compromises human sperm functions by an intracellular Ca2+ concentration-related mechanism
Introduction
Rosmarinic acid (RA) is a phenolic ester derived from caffeic acid and (R)-(+)-3-(3,4-dihydroxyphenyl)lactic acid. RA accumulates in high amounts in many plant species, and is especially abundant in many herbs of the Lamiaceae family, such as rosemary, mint, and basil [1,2]. The numerous biological and pharmacological activities of RA that have led to many clinical applications include antioxidant, antitumor, anti-fibrosis, anti-inflammatory, antimicrobial, and anti-neurodegenerative disease activities [[1], [2], [3], [4], [5]]. In addition, RA has long been used in the food, cosmetic, and fragrance industries [[6], [7], [8]]. The pharmacology and biotechnological applications of RA have been intensively studied during the last decade.
Recent studies have reported that RA can attenuate doxorubicin-induced testicular injury and reverse the negative effects of metronidazole-induced male infertility in rats [9,10]. RA also increases sexual behavior and testosterone levels in diabetic male rats [11]. In addition, the strong antioxidant activity of RA improves sperm function and in vitro fertilizing ability after sperm cryopreservation in several animals including boar [12], bull [13], and ram [14]. These results indicate that RA acts as a cytoprotective agent for male reproduction in animal models. However, the effect of RA on human sperm remains unclear. We recently described that a Chinese herb that has similar bioactivities to RA inhibits human sperm functions by reducing sperm intracellular calcium ion concentration ([Ca2+]i) and tyrosine phosphorylation [15]. Determining the effect of RA on human sperm is essential to expand the knowledge of the clinical adverse effects of RA and to evaluate the safety of RA as a cryopreservative agents of human sperm.
In this study, we evaluated the effects of RA on the viability, motility, capacitation, and acrosome reaction processes of human sperm, which are essential for fertilization. To understand the underlying mechanism, the effects of RA on sperm [Ca2+]i, currents of the cation channel of sperm (CATSPER) and potassium channel of sperm (KSPER), and intracellular cyclic adenosine monophosphate (cAMP) were examined.
Section snippets
Semen sample collection and treatments
Semen samples were obtained by masturbation after 3–5 days of sexual abstinence. The donors (25–38 years old) had reproductive history during the preceding 2 years and normal sperm quality according to the World Health Organization (WHO) laboratory manual for the examination and processing of human semen (http://www.who.int/reproductivehealth/publications/infertility/9789241547789/en/). The collection of the samples was approved by the Institutional Ethics Committee on human subjects of Jiangxi
RA treatment affects human sperm motility
To evaluate the effects of RA on sperm viability and motility at non-capacitated and capacitated stages, we incubated human sperm in HTF medium (a non-capacitated solution) for 1 h and in HTF++ medium (a capacitated solution) for 4 h, respectively. The results showed that human sperm viability was not significantly affected by the in vitro exposure to 1–1000 μM RA either at non-capacitated or capacitated stage (Fig. 1A). In addition, RA (10, 100 and 1000 μM) exposure for 1 h to human sperm at
Discussion
The various biological and pharmacological activities have led to the use of RA clinically, in foods, in everyday chemicals, and in agricultural applications [1,2,6,24]. These environmental and/or clinical RA exposures can be ubiquitous in daily life via multiple pathways. In addition, RA is a potential cytoprotective agent for sperm cryopreservation in animal models [[12], [13], [14]]. The latter use for human sperm is unresolved since the effect of RA on human sperm is unclear. It is
Conflict of interest
The authors declare that there are no conflicts of interest.
Acknowledgements
This work was supported by the National Key Research and Development Program of China (grant number 2016YFC1000905), National Natural Science Foundation of China (grant number 81771644), Natural Science Foundation of Jiangxi, China (grant numbers 20171ACB21006 and 20161BAB204167), and the open project of National Population and Family Planning Key Laboratory of Contraceptives and Devices Research (grant number No. 2016KF07).
References (33)
- et al.
Rosmarinic acid improves function and in vitro fertilising ability of boar sperm after cryopreservation
Cryobiology
(2014) - et al.
Antioxidant effect of rosemary (Rosmarinus officinalis L.) Extract in soybean lecithin-based semen extender following freeze–thawing process of ram sperm
Cryobiology
(2014) - et al.
Emodin inhibits human sperm functions by reducing sperm [Ca2+]i and tyrosine phosphorylation
Reprod. Toxicol.
(2015) - et al.
Lead inhibits human sperm functions by reducing the levels of intracellular calcium, cAMP, and tyrosine phosphorylation
Tohoku J. Exp. Med.
(2016) - et al.
Ketamine inhibits human sperm function by Ca2+-related mechanism
Biochem. Biophys. Res. Commun.
(2016) - et al.
Matrine compromises mouse sperm functions by a [Ca2+]i-related mechanism
Reprod. Toxicol.
(2016) - et al.
Ca2+ signals generated by CatSper and Ca2+ stores regulate different behaviors in human sperm
J. Biol. Chem.
(2013) - et al.
Rosmarinic acid inhibits Ca2+-dependent pathways of T-cell antigen receptor-mediated signaling by inhibiting the PLC-γ1 and itk activity
Blood
(2003) - et al.
SLO3 K+ channels control calcium entry through CATSPER channels in sperm
J. Biol. Chem.
(2014) - et al.
Rosmarinic acid--pharmaceutical and clinical aspects
Planta Med.
(2016)