Effect of Lepidium meyenii on in vitro fertilization via improvement in acrosome reaction and motility of mouse and human sperm

Abstract

Purpose: The direct effects of Lepidium meyenii (Maca) on sperm remain unclear. Herein, we examined the direct effect of Maca on in vitro fertilization.

Methods: We examined the fertilization rate in a mouse model and the rate of acrosome reaction in sperm from transgenic mice expressing enhanced green fluorescent protein (EGFP) in a Maca extract-containing human tubal fluid (HTF) medium. Using human sperm, we assessed acrosome status via fluorescein isothiocyanate-conjugated peanut agglutinin (FITC-PNA) staining and performed detailed analysis using a sperm motility analysis system (SMAS).

Results: In the mouse model, the fertilization rate in the Maca extract-containing HTF was significantly higher than that in the control medium. The acrosome reaction rate in sperm from transgenic mice expressing EGFP was also significantly higher in the Maca extract-containing HTF than that in the control medium. Similarly, a high acrosome reaction rate, identified via FITC-PNA staining of human sperm samples, was found in the Maca extract-containing HTF compared with that in the control medium. Human sperm motility in the Maca extract-containing HTF was also increased compared with that in the control medium as measured using an SMAS.

Conclusions: Maca improved in vitro fertilization rates by inducing an acrosome reaction and increasing sperm motility.

Keywords: Lepidium meyenii; Maca; acrosome reaction; in vitro fertilization; sperm motility.

Figure 1

Rate of successful fertilization determined as the proportion of two‐cell‐stage embryos among all mouse oocytes in the experiment. The fertilization rate in medium containing Maca extract at a concentration of 4% (w/v) with 1% DMSO was significantly higher (33.4% ± 7.6%) than that in HTF medium without Maca extract (14.3% ± 4.6%; P < 0.05). The fertilization rates in medium containing Maca extract at concentrations of 2% and 8% (w/v) were also higher (23.3% ± 5.9% and 20.7% ± 9.6%, respectively) than those in HTF medium without Maca extract, but these differences were not statistically significant. DMSO, dimethyl sulfoxide; HTM, human tubal fluid

Figure 2

The rate of acrosome reaction in mouse sperm. The rates of acrosome‐reacted sperm in HTF medium containing Maca extract at concentrations of 4.0%, 8.0%, and 16.0% (w/v) with 1% DMSO were significantly higher (68% ± 3.1%, 71% ± 1.2%, and 71% ± 2.9%, respectively) than those in medium without Maca extract (44% ± 5.1%; P < 0.05). The rate of acrosome‐reacted sperm in HTF medium containing Maca extract at a concentration of 2.0% (w/v) with 1% DMSO was also higher (59% ± 5.5%) than that in HTF medium without Maca extract, but this difference was not statistically significant. HTM, human tubal fluid; DMSO, dimethyl sulfoxide

Figure 3

The rate of acrosome reaction in human sperm. The rate of acrosome‐reacted sperm in HTF medium containing Maca extract at a concentration of 1.0% (w/v) with 1% DMSO was significantly higher (69% ± 7.3%) than that in medium without Maca extract (23% ± 5.4%; P < 0.01). The rates of acrosome‐reacted sperm in HTF medium containing Maca extract at concentrations of 0.5% and 2.0% (w/v) with 1% DMSO were also higher (39.6% ± 3.2% and 39.8% ± 5.8%, respectively) than those in HTF medium without Maca extract, but these differences were not statistically significant. HTM, human tubal fluid; DMSO, dimethyl sulfoxide

Figure 4

Sperm motility and amplitude of lateral head displacement in medium with or without Maca extract. Sperm motility was analyzed using a sperm motility analysis system. The percentage of sperm motility in the Maca extract‐containing medium was significantly higher (82.1% ± 5.1%) than that in the control medium (53.9% ± 9.5%; P < 0.05). The amplitude of lateral head displacement in the Maca extract‐containing medium was also higher (2.9 ± 0.3 μm) than that in the control medium (2.4 ± 0.2 μm), but this difference was not statistically significant