Involvement of calcium channels and intracellular calcium in bull sperm thermotaxis

Abstract

Thermotaxis that sperm migrate to higher temperature area has been confirmed in rabbit and human. In this study, we examined the migration ability of bull sperm in a temperature gradient to confirm thermotaxis and elucidate the involvement of calcium in such thermotaxis, as well as the relation between sperm capacitation and bull fertility. Thermotaxis was evaluated in a temperature gradient of 34–42ºC using a cross-type column 22-mm long, 40-mm wide, and 100-μm deep. Significantly more sperm migrated to the high-temperature area of 39ºC in a 2ºC temperature gradient, and to 40ºC in a 1ºC temperature gradient. In calcium-free, BAPTA containing medium, and EGTA containing medium, the migrated sperm ratio in the two temperature areas was almost the same. In media containing lanthanum, ruthenium red, and 2APB, we could not confirm thermotaxis. Pre- and post-capacitated sperm migrated to the high-temperature area, expressing thermotaxis. The sperm from high-fertility bulls showed clear thermotaxis. Based on these results, thermotaxis of bull sperm was confirmed and the involvement of both calcium channels and intracellular stored calcium in thermotaxis was suggested. Although the sample size of bulls was quite small, the difference in thermotaxis may have been associated with bull fertility. Sperm thermotaxis evaluation has potential as a predictor of bull fertility.

Bovine sperm selection procedure prior to cryopreservation for improvement of post-thawed semen quality and fertility

“…Another physical environment that worked on to facilitate sperm migration to the upper layer of the conical vessel is thermotaxis It has been reported that the migration of sperm in the female reproductive tract associated with fertilization is regulated by thermotaxis [30, 31]. The temperature gradient allows sperm to orientate their swim away from the utero-tubal junction (low temperature) towards the warmer ampulla where the oocyte awaits [32–34]. Thermotaxis of bull sperm was confirmed involving both calcium channels and intracellular stored calcium [34].…”

“…The temperature gradient allows sperm to orientate their swim away from the utero-tubal junction (low temperature) towards the warmer ampulla where the oocyte awaits [32–34]. Thermotaxis of bull sperm was confirmed involving both calcium channels and intracellular stored calcium [34]. Our SSRT method utilized this combined mechanisms of migration dynamics sensitive to temperature and rheological stimuli, and the obtained data indicate not only improvement of cryosurvival of prefreeze selected spermatozoa but compelling results in AI provide a solid evidence that pre-selection of high quality spermatozoa prior to cryopreservation by SSRT method is a robust means of improving the fertilization potential of bull semen.…”

Novel Techniques of Sperm Selection for Improving IVF and ICSI Outcomes

“…In addition, the use of these selected spermatozoa for ICSI in mice increased cleavage rates and blastocyst production, as well as implantation and live birth rate as opposed to the use of spermatozoa selected by SU. Although this is the only work related to the use of spermatozoa selected by thermotaxis in ARTs, a recent study carried out in bulls has shown that seminal samples delivering high pregnancy rates after artificial insemination show a greater response to thermotaxis (Mondal et al, 2016). However, as in the case of rheotaxis and chemotaxis, there are still no available publications showing the capability of sperm selection by thermotaxis to improve the ARTs efficiency in the human clinic.…”

Odorant and Taste Receptors in Sperm Chemotaxis and Cryopreservation: Roles and Implications in Sperm Capacitation, Motility and Fertility

“…Currently, three guidance mechanisms are known for the sperm movement including thermotaxis (swimming due to temperature gradient), Rheotaxis (swimming due to fluid flow gradient), and chemotaxis (swimming due to concentration difference of chemoattractants) which have been demonstrated in human, rabbit, mice, bull and pig [ 3 , 17 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]. How chemotaxis occur in sperm through the involvement of ORs and TRs is the focus of this review as expression or suppression of these receptors effect motility, fertility, and viability of post-thaw sperm.…”