Sperm physiology varies according to ultradian and infradian rhythms

Abstract

The spermatozoon must be physiologically prepared to fertilize the egg, process called capacitation. Human sperm samples are heterogeneous in their ability to capacitate themselves, which leads to variability between samples from the same or different donors, and even along the seasons. Here we studied sperm variation in the capacitation state according to the ability of capacitated spermatozoa to acrosome react upon stimulation (% ARi) and to be recruited by chemotaxis (% Chex). Both indirect indicators of sperm capacitation increased along the incubation time with fluctuations. Those capacitated sperm recruited by chemotaxis showed an ultradian rhythm with a cycle every 2 h, which might be influenced by unknown intrinsic sperm factors. Two infradian rhythms of 12 months for the % ARi and of 6 months for % Chex were observed, which are associated with the joint action of temperature and photoperiod. Thus, to avoid false negative results, human sperm samples are recommended to be incubated for a long period (e.g. 18 h) preferably in spring time. This innovative point of view would lead to better comprehend human reproductive biology and to think experimental designs in the light of sperm cyclicity or to improve sperm aptitude for clinical purposes.

Getting to and away from the egg, an interplay between several sperm transport mechanisms and a complex oviduct physiology

“…It has so far been observed in small subpopulations of capacitated human, mouse, rabbit, bovine and equine spermatozoa (Dominguez, 2019;Dominguez et al, 2018;Eisenbach and Giojalas, 2006;Giojalas et al, 2015;Moreno-Irusta et al, 2020). The chemotactic response lasts up to two hours (Cohen-Dayag et al, 1995;Fabro et al, 2002), fluctuating with an ultradian cycle of two hours, and also with an infradian seasonal rhythm, at least in humans (Moreno-Irusta et al, 2019). Interestingly, the chemotactic state is associated with the time a fertilisable oocyte is available in the oviduct.…”

Physiological Rhythms and Biological Variation of Biomolecules: The Road to Personalized Laboratory Medicine

“…Ultradian rhythms are essential for vital organ functions such as respiration, heart rate, peristaltic activity of the gastrointestinal tract, brain electrical activity [ 22 , 29 ], sperm physiology [ 30 ], thermoregulation [ 31 , 32 , 33 ], rapid eye movement (REM)/non-REM (NREM) sleep cycle, etc. [ 34 ].…”

“…For example, evidence show the effects of the ultradian rhythms on heart rate variability, gene expression, locomotor activity, and body temperature [ 214 ]. Similarly, infradian rhythms have been associated with reproduction, sperm physiology, telomer length, aging, etc., and the coordination of physiological rhythms are essentials for healthy behavior and memory functions [ 30 , 215 , 216 ]. Seasonal variations have been observed in telomer lengths [ 217 , 218 , 219 ] and shortening of telomere length is observed in cellular senescence and accepted as a biomarker for aging [ 220 , 221 ].…”

SERPINA5 Protein in Cumulus-Oocyte Complexes Increases the Fertilisation Ability of Mouse Sperm

“…to become competent to penetrate and fertilise the ovum [8,9]. Therefore, optimising the in vitro sperm capacitation process, an important research area in the field of reproductive medicine, is key to improving the quality of sperm used in ART.…”