Temperature-dependent hyperactivated movement of hamster spermatozoa.

Abstract

Immotile hamster spermatozoa from the caudal epididymis were activated in physiological medium at a temperature range between 22 and 40 degrees C. With rising temperature, the sperm swimming velocity and flagellar beat frequency increased, but the flagellar bend angles and waveforms did not change dramatically. All spermatozoa exhibited a symmetric and progressive movement at this temperature range. Hyperactivation was induced by incubating activated spermatozoa in vitro at 37 degrees C for 3.5 h under 5% CO2 in air. When examined at 37 degrees C, spermatozoa expressed a hyperactivated motility characterized by asymmetric and circular flagellar beating with large principal and reverse bends. When the temperature was lowered to 33 degrees C, the sperm motility pattern characteristic of hyperactivation became less prominent. In particular, the reverse bend originating in the flagellar middle piece did not propagate to the principal piece. However, normal hyperactivated movement was restored as the temperature was raised to 37 degrees C, indicating that in vitro expression of hyperactivated motility of hamster spermatozoa is a temperature-dependent phenomenon. To further investigate temperature effects on the flagellar motor apparatus, spermatozoa were demembranated and then reactivated with ATP. In contrast to membrane-intact hyperactivated spermatozoa, demembranated spermatozoa exhibited a hyperactivation-like motility independent of the temperature range tested (22-40 degrees C). This strongly suggests that temperature regulates initiation and maintenance of hyperactivated motility and that its effect is mediated by the plasma membrane.