Characterization of human sperm pattern of movement during chemotactic orientation towards Progesterone

GUIDOBALDI, HA; BLENGINI, CS; TEVES, ME; UÑATES, DR; GATICA, LV; MONTESINOS, MM; GIOJALAS, LC

Okinawa

Simposio; 11th International Symposium on Spermatology; 2010

Sperm chemotaxis is a mechanism that guides the spermatozoon towards the egg by following a road of increasing quantities of an attractant molecule. In contrast with external fertilizing species, mammalian spermatozoa do not show a visible change in the pattern of movement while the cells sense an ascendant attractant gradient, and then orient themselves towards the source of the chemoattractant. The aim of this study was to characterize the chemotactic behavior of human spermatozoa while sensing a gradient of a physiological attractant, Progesterone. Capacitated human spermatozoa were exposed to a descendant spatial-temporal gradient of chemotactic concentration of Progesterone (l0pM). Those spermatozoa that swim away from the attractant and then turn back to its source were analyzed by videomicroscopy and computer image analysis. When the spermatozoon swims away from Progesterone there are not visible changes in the linear pattern of movement. Then, when it is about 600 urn far from the source of Progesterone, it turns back on the direction to the attractant source, while increasing the curvilinear velocity and acquiring a transitional pattern of movement (characterized by a decrease in linearity and wobble parameters). This pattern of movement was interpreted as representative of chemotactic behavior since: 1) spermatozoa were exposed to a spatial-temporal gradient of Progesterone, therefore they can localize the source of the attractant and orient their movement towards it (for instance, a temporal gradient does not allow sperm orientation in the space), 2) the chemotactic pattern was expressed by a subpopulation of spermatozoa (10%), similarly to the expected level of capacitated — chemotactic cells, and 3) the chemotactic pattern was suppressed when the cells were previously incubated with an inhibitor of chemotaxis signaling (ddAdo). Hence, this chemotactic pattern of movement may be used as a marker for chemotactic spermatozoa, with potential application in Assisted Reproduction.