Time-related changes in functional activity and capacitation of chinchilla (Chinchilla lanigera) spermatozoa during in vitro incubation

The application of assisted breeding programs for chinchilla, an endangered species, requires detailed knowledge about their gamete physiology. Main purposes of the present study were to examine the time-related changes during 8 h in vitro incubation in parameters that reflect chinchilla sperm functional activity (including sperm motility, viability, membrane and acrosome integrity), and to determine the incubation time required for achieving in vitro sperm capacitation, evaluated through the quantification of the percentages of sperm that underwent the acrosome reaction in response to progesterone (P, 20 μM) or another acrosome reaction inducer the calcium ionophore, A23187 (20 nM). Semen was obtained by electroejaculation, subjected to swim-up and incubated for 0, 2, 4 and 8 h. After these periods, sperm functional activity was assessed. In all treatments percentages of motile, viable and viable sperm with intact acrosomes decreased (p < 0.001) after 8 h of incubation. The percentages of swollen gametes decreased (p < 0.001) after 2 h of incubation. Capacitation of chinchilla sperm could be achieved within 4 h, as indirectly demonstrated by the increase of acrosome reacted cells in response to P or A23187 (time × treatment interaction: p = 0.02).