ATP and ADP content of human ejaculated spermatozoa. II. Time-dependent changes after ejaculation

Metabolomic signature of spermatozoa established during holding time is responsible for differences in boar sperm freezability

Holding at room temperature is the first step in most boar semen cryopreservation protocols. It is well accepted that a holding time (HT) of 24 h increases sperm cryotolerance. However, the effect of HT on ejaculates with different freezability is not entirely clear. The aim of this study was to understand how HT influences spermatic and seminal plasma metabolite profiles of boar ejaculates and how these possible changes affect freezability. Twenty-seven ejaculates were collected and extended to 1:1 (v: v) with BTS and split into two aliquots. The first aliquot was cryopreserved without holding time (0 h), and the second was held at 17°C for 24 h before cryopreservation. Spermatozoa and seminal plasma were collected by centrifugation at two times, before HT (0 h) and after HT (24 h), and subsequently frozen until metabolite extraction and UPLC-MS analysis. After thawing, the semen samples were evaluated for kinetics, membrane integrity, mitochondrial potential, membrane lipid peroxidation, and fluidity. The ejaculates were then allocated into two phenotypes (good ejaculate freezers [GEF] and poor ejaculate freezers [PEF]) based on the percent reduction in sperm quality (%RSQ) as determined by the difference in total motility and membrane integrity between raw and post-thaw samples cryopreserved after 24 h of HT. The metabolic profile of the seminal plasma did not seem to influence ejaculate freezability, but that of the spermatozoa were markedly different between GEF and PEF. We identified a number of metabolic markers in the sperm cells (including inosine, hypoxanthine, creatine, ADP, niacinamide, spermine, and 2-methylbutyrylcarnitine) that were directly related to the improvement of ejaculate freezability during HT; these were components of metabolic pathways associated with energy production. Furthermore, PEF showed an up-regulation in the arginine and proline as well as the glutathione metabolism pathways. These findings help to better understand the effect of holding time on boar sperm freezability and propose prospective metabolic markers that may predict freezability; this has implications in both basic and applied sciences.

Adenosine triphosphate (ATP) in human spermatozoa

The seminal adenosine triphosphate (ATP) content was determined by bioluminescence after treatment with trichloroacetic acid (TCA) in 81 semen samples 1.5 h after ejaculation obtained from men attending our fertility clinic, and selected to contain either 20% or less spermatozoa with good progressive motility (n = 22), or 60% or more spermatozoa with good progressive motility (n = 59) (Study I), and in 18 semen samples from fertile men 30 min and 3.5 h after ejaculation (Study II). The latter samples were divided into 2 equally large groups according to sperm motility. In Study I the mean sperm ATP concentration was significantly higher in the semen samples with bad motility (0.63 nmol per living spermatozoa x 10(-6)) than in semen samples with good motility (0.39 nmol per living spermatozoa x 10(-6); P less than 0.01). In Study II the ATP concentration per living spermatozoa was also lower in the group with the best motility in comparison with the spermatozoa with lower motility (P less than 0.01), both 30 min and 3.5 h after ejaculation. During the 3-5 h incubation the sperm ATP concentration decreased by 21% (P less than 0.01) in the former group of samples but remained unchanged in the latter group. The results indicate that, in semen samples with highly motile spermatozoa, the consumption of ATP is higher than in semen samples with impaired sperm motility. It is therefore essential that the time between ejaculation and ATP measurement is as short as possible to obtain comparable results. Repeated ATP measurements in combination with an analysis of the number of living spermatozoa, may provide further information on the fertilizing capacity of spermatozoa.

Sperm motility and interactions among seminal uridine, xanthine, urate, and ATPase in fertile and infertile men

Semen was collected under standardized conditions from men who were divided into three groups: a control group from normal spermiograms, men with abnormal spermiograms, and azoospermic men following vasectomy. Ultracentrifuged seminal plasma was analyzed for uridine, xanthine, urate, and the pelleted material for Mg2+- and Ca2+-dependent ATPase and protein. No significant intergroup differences were noted except the significant elevation of xanthine of vasectomized men. Uridine that occurs in high concentration in seminal plasma displayed a positive correlation to percentage motile sperms from the 26 men with normal and abnormal spermiograms. It was concluded that an optimal secretory function of uridine may parallel the increasing percentage of sperm with a better quality of motility. A linear relationship between ATPase activity and sperm penetration ability existed only when taken into consideration those 13 specimens with lowest enzyme activity.

Effects of methyl xanthines upon the spermatozoa adenosinetriphosphate (ATP) concentration in normal semen

The aim of the present study was to ascertain the effect of methyl xanthines upon the spermatozoa ATP concentration in normal semen in vitro. 26 normal semen were studied. The specimens were diluted after liquefaction with equal volume of Lopata's buffer or Lopata's buffer plus 1 or 6 mM either of caffeine or pentoxifylline. The samples of semen were incubated at room temperature during 90, 180 and 240 minutes before motility and ATP determination by the firefly luciferin-luciferase method. Significant variation was observed in sperm motility nevertheless variations in the ATP concentration was not induced by any of the methyl xanthines we used.