Induced hyperactivity in boar spermatozoa and its evaluation by computer-assisted sperm analysis

Abstract

Hyperactivity, a form of sperm motility characterized by vigorous flagellar movements, has been proposed as essential for fertilization in mammals. The objective of the present study was to establish a method for inducing hyperactivity in vitro in boar spermatozoa and to define threshold values to differentiate between hyperactive and non-hyperactive spermatozoa by computer-assisted sperm analysis (CASA) as a prerequisite for analyzing the energy metabolism during hyperactivity. In TALP-HEPES medium, non-frozen boar spermatozoa were stimulated to hyperactivity by 50 mmol l to-head agglutination were low so that hyperactive spermatozoa could be analyzed for at least 40 min. The transition from normal to hyperactive movement was characterized by an increase in flagellar beat angle from 498 6 128 to 2008 6 368 (n 5 32) and a decrease in flagellar curvature ratio from 0.89 6 0.04 to 0.47 6 0.11 (n 5 32). For quantification of hyperactive boar sperm, kinematic parameters of hyperactive and non-hyperactive spermatozoa were measured by CASA and statistically evaluated (receiver operating characteristic (ROC) curve analysis). The threshold values of the following four parameters were well suited for differentiating between hyperactive and non-hyperactive boar spermatozoa (ROC curve analysis: >50% specificity at 100% sensitivity). Hyperactive boar spermatozoa showed mean lateral head displacement >3.5 mm, curvilinear velocity >97 mm s 21, linearity < 32% and wobble <71%. According to this multiparametric definition, induction of hyperactivity increased significantly (P < 0.0001) the fraction of hyperactive spermatozoa in semen samples from 5.1 6 4.3% (n 5 13) to 48.3 6 6.6% (n 5 7) in the absence and to 44.2 6 7.6% (n 5 10) in the presence of 25% seminal plasma, while the overall percentage of motile spermatozoa did not change significantly.

Porcine sperm capacitation involves tyrosine phosphorylation and activation of aldose reductase

“…The changes in the motion parameters induced by capacitation were the characteristic of hyperactivated sperm, i.e. increases in VCL, VSL, VAP, and ALH as well as decreases in LIN and STR (Schmidt & Kamp 2004, Matás et al 2010; Table 2). These changes were also inhibited by alrestatin.…”

“…Motion parameters such as curvilinear velocity (VCL; mm/s), straight-line velocity (VSL; mm/s), average path velocity (VAP; mm/s), linearity of the curvilinear trajectory (LIN; VSL!100/VCL), straightness (STR; VSL!100/VAP), amplitude of lateral head displacement (ALH; mm), and beat cross-frequency (Hz) were determined. For flagellar movement analyses, sperm motility was recorded by Nikon-NY-D5100 Super System (Microscope Network, Saitama, Japan) on the slide glass with 0.02 mm depth (Hamilton Thorne Research), and both the flagellar beat angle (FBA) and the flagellar curvature ratio (FCR) were determined according to the method of Schmidt & Kamp (2004), as shown in Supplementary videos 1 and 2, see section on supplementary data given at the end of this article and Fig. 1b.…”

“…FBA and FCR were determined as shown in Fig. 1b (878) and FCR (0.7) for those of boar sperm hyperactivated in the presence of the Ca 2C ionophore A 23187 (Schmidt & Kamp 2004).…”

Proper use and impact of ‘Computer Assisted Semen Analysis’ technique on semen evaluation of farm animals

“…The particular characteristics of hyperactive motility are increased VCL and ALH and decreased LIN, STR, WOB and BCF (Schmidt and Kamp, 2004). For hyperactivated sperms of men, kinematic definition motility is as follows: VCL ~150 μm s -1 , ALH ~7 μm and LIN ≤0.5 (Mortimer, 1997).…”

“…For hyperactivated sperms of men, kinematic definition motility is as follows: VCL ~150 μm s -1 , ALH ~7 μm and LIN ≤0.5 (Mortimer, 1997). In hyperactivated sperms of bulls, kinematic definition motility is VCL ≥70 μm s -1 and ALH ≥7μm (Kathiravan et al, 2011) and in those of boars VCL >97μm s -1 , ALH >3.5 μm, LIN <0.32 and WOB <0.71 (Schmidt and Kamp, 2004).…”