Sperm chemorepulsion, a supplementary mechanism to regulate fertilization

GUIDOBALDI, H.A.; CUBILLA, M.; MORENO, A.; MOLINO, M.V.; BAHAMONDES, L.; GIOJALAS, L.C.

HUMAN REPRODUCTION

OXFORD UNIV PRESS

Año: 2017 p. 1 - 14

0268-1161

Study question: Are human spermatozoa able of chemorepulsive behavior?Summary answer: Capacitated human spermatozoa are able to be chemorepelled by synthetic Progesterone Receptor Ligands (sPRL, known as contraceptives) and zinc (a cation released by the oocyte upon fertilization).What is known already: Moving cells can be oriented towards or against a molecular gradient, processes called chemoattraction and chemorepulsion, respectively, which have been described in unicellular organisms such as amoebas and bacteria, to organismic cells such macrophages and developmental cells. In the case of spermatozoa, chemoattraction may help the finding of an oocyte and has been widely studied in various invertebrate and mammalian species; however, chemorepulsion has not yet been verified in spermatozoa.Study design, size, duration: This is an in vitro study involving human, rabbit and mouse spermatozoa which were used to perform 3 to 30 experiments per treatment. Participants/materials, setting, methods: Human sperm samples were obtained by masturbation from healthy donors who gave written consent. Only those samples exhibiting normal semen parameters according to current WHO criteria were included in the study. Rabbit spermatozoa were obtained by artificial vagina whereas mice spermatozoa were obtained from epididymis. The Sperm Selection Assay (SSA), originally designed to evaluate sperm chemoattraction towards progesterone (P), and a video-microscopy and computer motion analysis system were used to test sperm chemorepulsion. Additional kinetic parameters were also determined by video-microscopy and computer motion analysis. In some experiments, the level of induced acrosome-reacted spermatozoa was determined. Rabbit mating manipulation was achieved to perform the sperm - oocyte co-incubation assay. Main results and the role of chance: Sperm accumulation in the well containing 100 pg/ml of synthetic Progesterone Receptor Ligands (sPRL) was lower than the culture medium negative control (p