Dioscorea bulbifera tubers contain several phytochemicals of pharmaceutical value. They have been traditionally used for treating various ailments, including postmenopausal symptoms. In the present study, we analyzed the direct effects of Dioscorea tuber extract on mouse spermatozoa. Its contraceptive effect was also evaluated by an intravaginal application before copulation. Mouse spermatozoa were cultured in vitro with various concentrations of the extract. After culturing, the spermatozoa were stained with fluorescein isothiocyanate peanut agglutinin or Coomassie blue to study the acrosome reaction, stained with trypan blue to study the viability, or treated with a hypo-osmotic medium to study the membrane damage. Estrous female mice were intravaginally injected with the extract and copulated with males. The extract induced acrosome exocytosis, viability loss, and membrane damage in a concentration-dependent manner. Female mice treated with the extract showed complete loss of fertility. These observations indicate that the Dioscorea bulbifera tuber extract could be used as a topical contraceptive. Infertility could be due to the precocious acrosome exocytosis of the spermatozoa or membrane damage.
Figures & Tables
Fig. 1. Effect of the extract on acrosome reaction of mouse spermatozoa. (A) Mouse spermatozoa doubly labeled with fluorescein isothiocyanate (FITC) conjugated lectin from Arachis hypogaea (peanut; PNA) and ethidium bromide (EtBr). Spermatozoa with intact acrosomes displayed crescentshaped fluorescence on the dorsal surface of the heads (arrow). Spermatozoa lacking acrosomes do not display green labeling. Sperm nuclei appeared as red falciform structures due to the EtBr labeling of DNA (arrowhead). (B) Mouse spermatozoa stained with coomassie blue. The acrosome was visible as a thick blue arc on the dorsal surface of the head (arrow). Sperm heads lacking acrosomes were devoid of such staining (arrowheads). (C) Acrosome exocytosis caused by various concentrations of the extract. Increase in concentration of the extract caused a higher percentage of acrosome exocytosis. The columns marked by different letters indicate significantly different values. Scale bars in (A) and (B) indicate 10 μm.