Factors Affecting Sperm Motility. IV. Incubation of Human Semen with Caffeine, Kallikrein, and Other Metabolically Active Compounds**Supported by Grant 48-6-90 from the Israel Commission for Basic Research.††This paper is part of an annual composition to fulfill the requirements for graduation from Harealy High School, Haifa, Israel (E. M.)

Extend the Survival of Human Sperm In Vitro in Non-Freezing Conditions: Damage Mechanisms, Preservation Technologies, and Clinical Applications

Preservation of human spermatozoa in vitro at normothermia or hypothermia maintaining their functions and fertility for several days plays a significant role in reproductive biology and medicine. However, it is well known that human spermatozoa left in vitro deteriorate over time irreversibly as the consequence of various stresses such as the change of osmolarity, energy deficiency, and oxidative damage, leading to substantial limitations including the need for semen examinations, fertility preservation, and assisted reproductive technology. These problems may be addressed with the aid of non-freezing storage techniques. The main and most effective preservation strategies are the partial or total replacement of seminal plasma with culture medium, named as extenders, and temperature-induced metabolic restriction. Semen extenders consist of buffers, osmolytes, and antioxidants, etc. to protect spermatozoa against the above-mentioned adverse factors. Extended preservation of human spermatozoa in vitro has a negative effect on sperm parameters, whereas its effect on ART outcomes remains inconsistent. The storage duration, temperature, and pre-treatment of semen should be determined according to the aims of preservation. Advanced techniques such as nanotechnology and omics have been introduced and show great potential in the lifespan extension of human sperm. It is certain that more patients will benefit from it in the near future. This review provided an overview of the current knowledge and prospects of prolonged non-freezing storage of human sperm in vitro.

Caffeine increased progressive motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples and enhanced activity of seminal creatine kinase

Even though the effect of caffeine on humans' health has been revealed in various research studies, its effect on semen quality has yet to be well explained. Here, we measured the effect of caffeine at 1, 5, 10 and 20 mM on motility of human spermatozoa in normozoospermic and asthenozoospermic semen samples, level of seminal nitric oxide, chelation of seminal calcium ions and activity of seminal creatine kinase. Fifty-one normozoospermic and ten asthenozoospermic semen samples were recruited in this study. Sperm motility was evaluated by Makler counter, and seminal nitric oxide, seminal-free calcium and activity of seminal creatine kinase were measured spectrophotometrically. Caffeine at 10 mM significantly (p < .05) increased progressive motility of spermatozoa in both tested groups. Also, caffeine significantly increased (p < .05) activity of creatine kinase and insignificantly (p > .05) altered nitric oxide and free calcium levels in seminal plasma. In conclusion, progressive motility of human spermatozoa was found to be higher in the presence of caffeine at 10 mM in normozoospermic and asthenozoospermic semen samples; this increase, albeit partially, could be due to increased activity of seminal creatine kinase, but not to increased production of nitric oxide or chelation of free calcium ions.

In vitro fertilization embryo development from caffeine-treated murine sperm

Purpose

To evaluate the effect of long-term caffeine administration on murine sperm and subsequent in vitro fertilization (IVF).

Methods

Male mice were injected with various doses (0, 0.2 and 1.0 mg/mouse/day) of caffeine for 1 month. After sperm collection, the IVF rate and embryo development to the blastocyst stage were evaluated.

Results

The mean body weight significantly decreased in the 1.0 mg/day treatment group compared to the control group (P < 0.01). Testicular weight and histological features did not differ, and total blood testosterone was no different in spite of the difference between 0.2 and 1.0 mg/day of caffeine. The IVF rate differed significantly between the control group [100/105 (95.2 %)] and 0.2 mg/day group [106/121 (87.6 %)] (P < 0.05). Furthermore, blastocyst formation was significantly and dose-dependently lower with higher caffeine levels: control group: 85/100 (85.0 %); 0.2 mg/day group: 84/106 (79.2 %) (P < 0.05); 1.0 mg/day group: 64/102 (62.7 %) (P < 0.001).

Conclusions

Caffeine treatment affected body weight of male mice. However, testicular weight, histological features and total blood testosterone concentration were not statistically different. In addition, following IVF using sperm from these mice, blastocyst formation decreased in a dose-dependent manner. These findings suggest that embryo development from oocytes fertilized with sperm from caffeine-administered male mice is negatively affected.

Effect of Visible Light on Human Sperm Motility

The study was carried out on 14 human semen good-quality samples, selected from a total number of 33 samples collected in a dark room close to laboratory. The mode of collection was masturbation. Samples remained in dark, and liquefaction time was observed under dim (red) light. This time was considered as the zero hour of the experiment. After liquefaction, each sample was divided into 2 parts. One portion was kept in the same dark laboratory and the other portion was shifted to the illuminated laboratory. The intensity of light present in dark, illuminated laboratory and on microscopic platform was measured with lux meter. From zero hour, every hour, up to 10 hours samples in dark and light were observed for percentage as well as quality of motility. The results showed that spermatozoa in light deteriorated earlier in their percentage and quality of motility, whereas in dark the quality of motility was superior. The spermatozoa survived for a large number of hours here. The Authors believe that female genital system where dark exists must be experiencing the same where spermatozoa remain increased in longevity and better quality. This study reveals that available knowledge on sperm motility does not match with what probably happens in female genital system.

Asthenozoospermia: analysis of a large population

Spermatozoa travel a long distance to meet and fertilize the oocyte, so sperm motility is a requisite for normal fertilization. Asthenozoospermia, or low sperm motility, is a common cause of human male infertility. This is a retrospective study (1992-1999) to document the prevalence of this pathology in infertile men and to clarify the probable factors associated to its etiology. The prevalence was 18.71% for asthenozoospermia and 63.13% for asthenozoospermia associated with oligo- and/or teratozoo-spermia; thus, 81.84% of the studied samples had altered motility. Leukocytospermia, the ratio of germ cells/sperm, anti-sperm antibodies, consistency, biochemical markers of accessory sex glands, and sperm response after swim-up were studied in normospermic (N), asthenozoospermic (A), and combined asthenozoospermic (C) samples. No significant difference was found in the frequency of leukocytospermia among groups. The rate of germ cells/(spermatozoa + germ cells) between C and N (p < .01) and C and A (p < .01) was statistically different, while no difference was found on comparing N and A. MAR-test over 40% was found in 6% of the A samples and 7.6% of the C, while no positive values were observed in the N group. The percentage of hyperviscous samples was higher in the low sperm motility samples than in the normal group. Data on concentration of the biochemical markers seem to be decreased in asthenozoospermia. Pure and combined asthenozoo-spermia showed different behavior in sperm recovery after swim-up. Two different asthenozoospermias could be defined: the pure one where sperm environment is involved (immunological factor, hyperviscosity, and secretory gland function) and the combined, where the testis is comprised.

Effect of pentoxifylline on motility and membrane integrity of cryopreserved human spermatozoa

The purpose of this study was to examine the effects of pentoxifylline used before and after semen cryopreservation-thawing on sperm motility and membrane integrity. Twenty-four semen samples were split into four equal aliquots. Aliquots were incubated at 37 degrees C for 30 min, followed by cryopreservation with TEST-yolk freezing medium using slow programmable freezing protocol. After 2 weeks the sperm samples were thawed, washed twice in Quinn's Sperm Washing Medium (modified HTF with 5.0 mg/mL Human Albumin) and incubated at 37 degrees C for 30 min. Aliquots were treated by adding 3 mmol/L pentoxifylline to: (1) fresh sperm samples during incubation period prior to cryopreservation, (2) sperm samples as a supplement to the cryoprotectant prior to cryopreservation, and (3) thawed sperm samples during incubation period. One aliquot received no treatment (control group). The addition of 3 mmol/L pentoxifylline to fresh semen during incubation period prior to cryopreservation significantly decreased progressive and total motility compared with controls. However, the addition of 3 mmol/L pentoxifylline to cryopreserved semen after thawing significantly increased progressive and total motility compared with controls. After post-thaw, no differences in motion characteristics between sperm samples treated by adding 3 mmol/L pentoxifylline as a supplement to the cryoprotectant and control groups were observed. Post-thaw hypoosmotic swelling (HOS) test scores did not improve with the addition of pentoxifylline compared with the control group. It is concluded that pentoxifylline enhanced post-thaw motility of cryopreserved human spermatozoa when added after thawing. No improvement was found by freezing sperm with pentoxifylline.

The effects of methylxanthines on the mobility of stored turkey sperm

The mobility of pooled turkey sperm following various storage regimens was assessed by objectively measuring the ability of sperm to penetrate a 2% Accudenz [5-(N-2,3-dihydroxypropylacetamido)-2,4,6-tri-iodo-N,N'-bis(2,3-dihydroxypropyl)isophthalamide] solution at 41 C. When semen was diluted with Beltsville poultry semen extender and stored at 5 C with agitation at 150 rpm, sperm mobility declined as the storage interval increased (P < or = 0.05), with mobility scores (mean +/- SEM) of 0.440+/-0.029, 0.374+/-0.031, 0.282+/-0.011, 0.202+/-0.019, and 0.130+/-0.019 for 0-, 3-, 6-, 24-, and 48-h storage, respectively. For a 10-wk fertility trial using the same storage method, sperm mobility and fertilizing capacity of semen were significantly reduced following 24-h storage compared with values for unstored semen. The sperm mobility scores were 0.404+/-0.051 and 0.101+/-0.046 for unstored and 24-h stored semen, respectively, whereas the percentage of fertilized eggs was 95.9+/-5.1 for unstored semen and 48.0+/-5.1 for 24-h stored semen. When caffeine or pentoxifylline was added to semen at 2.5, 5, or 10 mM, no significant effect on sperm mobility was seen, regardless of whether these compounds were added to unstored semen, were present during 6-h storage, or were added following the 6-h storage interval. These studies demonstrate that sperm mobility and fertilizing capacity of pooled turkey semen declines with storage, and that addition of caffeine or pentoxifylline either during or after storage does not affect sperm mobility.

The use of pentoxifylline to improve motility of cryopreserved equine spermatozoa

Pentoxifylline was evaluated as a method to increase motility of cryopreserved equine spermatozoa. In a preliminary experiment, pentoxifylline (3.5 mM or 7.0 mM) was added to extended semen that was chilled to 4 degrees C. Motility was evaluated at 8-h intervals for 48 h. The addition of 3.5 or 7.0 mM pentoxifylline appeared to increase the motility of chilled spermatozoa compared to controls. Based on these results, similar concentrations of pentoxifylline were added to semen either before or after cryopreservation. The addition of pentoxifylline (3.5 or 7.0 mM) to semen before cryopreservation significantly (P < 0.001) decreased total and progressive motility compared to controls. However, the addition of pentoxifylline (3.5 or 7.0 mM) to cryopreserved semen immediately after thawing significantly (P < 0.01) increased total and progressive motility compared to controls. These results indicate that pentoxifylline enhanced the postthaw motility of cryopreserved equine semen when added after thawing. Further research is required to evaluate the effect of pentoxifylline on the fertility of cryopreserved equine semen.

Sperm motility and ATP content in seminal hyperviscosity

Objective spermatic motility (Hamilton Thorne Research), the rapid progressive spermatozoa (grade A) recovery after swim-up, and the spermatozoa ATP content (bioluminescence) were studied in normoviscous and hyperviscous asthenospermic samples. The amplitude of lateral head displacement (ALH) was significantly lower in hyperviscous semen (normal: 4.6 +/- 0.7 microns [n = 20], high: 3.5 +/- 1.2 microns [n = 16]; p < .05). The grade A recovery percentage after swim-up was significantly higher in semens with high consistency (normal: 71.0 +/- 38.0 [n = 14], high: 181.3 +/- 108.9 [n = 6]; p < .05). The ATP content per living spermatozoa was in the normal consistency group 449.4 +/- 65.1 pmol per million living spermatozoa (n = 29) and in the high consistency batch 605.1 +/- 242.8 (n = 9), p < .05. In asthenospermia, the spermatozoa from hyperviscous samples have minor ALH values, better response to swim-up, and high ATP content than those from normoviscous ejaculates.

The effect of bradykinin and the bradykinin antagonist Hoe 140 on kinematic parameters of human spermatozoa

Bradykinin (BK) has been suggested to be an active substance in the disputed therapeutic use of kallikrein to improve semen quality. The effects of exogenous BK and its antagonist Hoe 140, which acts on one of the bradykinin receptors (BK2), were examined in two groups of patients attending the fertility clinic: those with asthenozoospermia (group I) and normozoospermia (group II). Bradykinin (10nM-1 microM) added to washed human spermatozoa had no effect on most kinematic parameters and caused only a marginal increase (7%) in curvilinear velocity at 50 nM in group I patients; however, this increase was not suppressed by concomitant addition of the BK antagonist. The bradykinin antagonist itself had no effect on the percentage motility or kinematic motility parameters of washed human spermatozoa in either group of patients. The motility of spermatozoa in semen was also unaffected by the presence of the bradykinin antagonist. It is concluded that bradykinin does not act exogenously on washed spermatozoa nor endogenously on spermatozoa in semen to stimulate motility via BK2 receptors, regardless of the initial quality of the sperm motility.

A study of spermatozoal motility in type 1 diabetes mellitus

The aim of the study was to examine an aspect of male fertility in patients with Type 1 diabetes mellitus (n = 17) compared to healthy control subjects (n = 16) using parameters of sperm motility, measured using a computerized image analysis system (the Hamilton Thorn Research HTM-2030 Motility Analyzer), as indicators of potential fertility. Within the diabetic group no correlations were found between sperm motility and age, age of onset of diabetes, duration of diabetes or glycated haemoglobin. When the diabetic and control groups were compared, track speed, path velocity, progressive velocity, and lateral head displacement were not significantly different, whereas linearity and linear index, measures of straightness of swimming, were significantly greater in the diabetic subjects (59.2% vs 69.8%, p = 0.0005 and 76.4% vs 83.6%, p = 0.0016, respectively). We conclude that diabetic men, in the absence of complications, do not appear to be at a disadvantage in terms of sperm motility compared to healthy individuals.

Effect of pentoxifylline on human sperm motility and fertilizing capacity

The effect of pentoxifylline (PF) treatment on human sperm motility and fertilizing capacity was assessed in 43 couples undergoing IVF/ET, as well as in 84 couples treated with AIH/IUI. Sperm motility increased following PF treatment in asthenospermic samples (n = 12) from 39.2 +/- 1.5 to 45.5% +/- 2% (p = .05), in oligoasthenospermic (n = 40) from 38.1 +/- 1.6 to 43.6 +/- 1.7% (p = .001), and in total (n = 127) from 50 +/- 1 to 52.5 +/- 1% (p < .001). In addition, PF incubation of sperm samples resulted in higher sperm motility values compared to swim-up in all categories of sperm samples. Furthermore, progressive motility increased in all sperm groups following PF treatment (astheno-spermic: +16.7%; oligoasthenospermic: +14%, p < .001; oligozoospermic: +23.5%, p < .001; normozoospermic: +15.3%, p < .05; total +19.2%, p < .001). Sperm preparation with PF resulted in higher fertilization rates in all categories of sperm samples compared to swim-up (total: 46.6 vs. 29.1%, respectively; p < .05). Moreover, PF treatment of human sperm resulted in 9 viable pregnancies (IVF/ET: 5, AIH/IUI: 4) and one biochemical (IVF/ET). PF improving sperm motility and fertilizing capacity appears to be a promising motility stimulant.

The effects of cyclic adenosine monophosphate, forskolin, and theophylline on motility parameters in gossypol-treated human sperm

OBJECTIVE

To examine the effect of gossypol on human sperm in vitro and the mechanism for the effect.

DESIGN

Fresh sperm ejaculates obtained from normal donors to the University of Kentucky Andrology Donor Program were exposed to gossypol. Motility was studied manually and using computer-assisted sperm analysis. In subsequent experiments, the effects of forskolin, theophylline, and cyclic adenosine monophosphate (cAMP) on sperm motion were measured.

SETTING

University of Kentucky Department of Obstetrics and Gynecology Andrology Laboratory.

MAIN OUTCOME MEASURES

Manual and computer-assisted measurements of sperm motility and motion characteristics.

RESULTS

Gossypol inhibited sperm motility, which could be reversed partially by increasing cAMP.

CONCLUSION

Gossypol exposure in vitro adversely affects sperm motility in a dose- and time-dependent manner by a cAMP-dependent mechanism.

The effect of caffeine on the ability of spermatozoa to fertilize mature human oocytes

Although caffeine has been reported to enhance spermatozoon motility as well as fertilizing ability, its use in clinical practice has remained sparse. We report here the results carried out to assess the effect of exposing normal human spermatozoa to different concentrations of caffeine on their motility, their ability to fertilize oocytes, and the subsequent development of resulting embryos. Mature human oocytes were inseminated with spermatozoa washed and capacitated in 1.25, 2.5, and 5 mM caffeine. The fertilization rates were compared with control oocytes inseminated with untreated spermatozoa. While caffeine was observed to improve significantly various motility parameters in a dose-dependent manner, it did not lead to an improvement in the fertilization rates. At the highest concentration, 5 mM, it adversely affected the fertilization rate: 38%, compared with 78% in controls. Embryonic development was also observed to be retarded at the lower concentrations, while it was virtually inhibited in the 5 mM concentration group. Our results suggest that while a definite improvement in motility may occur when spermatozoa are exposed to caffeine, this improvement did not translate into enhanced fertilizing ability and subsequent embryonic development. We are therefore of the opinion that the use of caffeine as a spermatozoon motility enhancer requires further studies prior to wider clinical use in assisted pregnancy programs.

Comparison of motility stimulants for cryopreserved human semen

Caffeine, pentoxifylline, 2-deoxyadenosine, cyclic adenosine monophosphate (cAMP), relaxin, adenosine, kallikrein, and calcium were compared for their ability to stimulate motility of cryopreserved sperm. Caffeine, pentoxifylline, and 2-deoxyadenosine significantly increased the percentage of motile sperm at 15, 30, 45, and 60 minutes after administration. Sperm velocity was significantly increased by caffeine at 0, 15, 30, and 45 minutes, and by pentoxifylline at 0, 45, and 60 minutes. Consistent stimulation was not observed for other chemicals. Caffeine, pentoxifylline, and 2-deoxyadenosine were then examined for their ability to provide motility stimulation after removal with washing. With the exception of caffeine, percent motility and velocity for stimulated and untreated sperm were similar after washing. A significant reduction in motility was observed at 48 hours after washing for caffeine. The percentage of hamster oocytes penetrated at 24 hours after washing was significantly reduced for caffeine, 2-deoxyadenosine, and pentoxifylline combined with 2-deoxyadenosine. Pentoxifylline-treated sperm showed no reduction in fertilizing capacity. These results indicate that, of the chemicals examined, pentoxifylline is superior for motility stimulation of cryopreserved sperm.

Temperature-dependent effects of the components of kallikrein-kinin system on sperm motility in vitro

The effect of kallikrein and bradykinin on sperm motility was studied. For investigation of whether the effect is not temperature dependent, sperm motility and velocity were measured after incubation with kallikrein or bradykinin at different temperatures. The effect of kallikrein on sperm motility and velocity was demonstrated significantly at 22 degrees C. At 37 degrees C, this effect was absent, but with captopril the effect of kallikrein on sperm velocity was observed. Bradykinin stimulated sperm motility and velocity at 22 degrees C and at 33 degrees C. However, it did not stimulate sperm motility at 37 degrees C. With 1.10 phenantroline, the effect of bradykinin on sperm motility was detected. These results indicate that kallikrein and bradykinin stimulate sperm motility and velocity and that their effects are strongly temperature dependent.

Effect of washing and suspension on penetration of human sperm into bovine cervical mucus

The in vitro penetration ability of human sperm into bovine cervical mucus after washing and suspension of the sperm in Earl's medium was compared with that of untreated sperm. The extent of penetration was found to be significantly lower in sperm washed and suspended in Earl's medium than in the unwashed sperm (p less than 0.0001); it increased to some extent on resuspension of the washed sperm in the seminal plasma but still remained significantly lower than that of intact sperm (p less than 0.009). The introduction of caffeine into the Earl's medium resulted in an increased penetration of the washed sperm into bovine cervical mucus, but this was still significantly lower than the penetration of the unwashed sample (p less than 0.02). The data point to the effectiveness of the seminal plasma as a medium facilitating sperm penetration through bovine cervical mucus.

Properties of human epididymal sperm obtained from an alloplastic spermatocele: motility assessment and penetration of zona-free hamster oocytes in the presence and absence of caffeine

Sperm were collected over a period of months from a human alloplastic spermatocele implanted at the corpus/caudal epididymal junction and were evaluated for their maturity, motility, and ability to capacitate and acrosome react, as assessed by the hamster zona-free oocyte sperm penetration assay (SPA). A mean of 11 X 10(6) sperm were obtained with each aspiration, with 34% to 40% being mature, normal forms. Motility was poor; 15% +/- 5% showing nonprogressive movement. SPA results were 22% +/- 3% oocyte penetration. Addition of 7.5 mM caffeine markedly enhanced motility and improved the SPA results. After 30 minutes' exposure, the motility was 45% +/- 5%, with all spermatozoa exhibiting progressive movement. This stimulation was maintained over a 24-hour period. When caffeine was present during the 2-hour preincubation for the SPA, penetration rates increased to 50% +/- 10% (P less than 0.05). These results demonstrate that the poor-quality sperm retrieved from a human alloplastic spermatocele can be improved with exogenous stimulation and suggest that their fertilizing capacity may be enhanced by this treatment.

Significance of adenosinetriphosphate in human sperm as clinical parameter

Washed human spermatozoa from 21 individuals with an average motility of 60% (quality index 277 +/- 16) had an endogenous ATP generation of 7.5 +/- 3.4 nmole/10(8) spermatozoa. The ATP concentrations in spermatozoa from 16 patients with severely impaired motility of 26% (quality index 98 +/- 13) was 16.9 +/- 9.9 nmole/10(8) spermatozoa. There was no correlation between ATP content and motility in either group. Sperm penetration into blood serum type AB, Rh-positive, was evaluated using a capillary tube penetration test. The penetration was graded with a maximum score of 14. Spermatozoa with an initial motility of 60% reached a score of 10 +/- 0.7. After addition of 20 mmole of ATP the score was significantly improved to 13 +/- 0.3. Compared with these results spermatozoa with an average motility of 26% reached a score of 4 +/- 1. Exogenous ATP (20 mmole) increased the score to 8 +/- 1.0. In both groups reduced glutathione had a negative effect. Human spermatozoa with high and low motility are capable to synthesize ATP. A dysfunction of the phosphorylating particles in the mitochondria appears not to be associated with low sperm motility.

The stimulatory effects of caffeine, theophylline, lysine-theophylline and 3-isobutyl-1-methylxanthine on human sperm motility

The potencies of caffeine, theophylline, lysine-theophylline and 3-isobutyl-1-methylxanthine (IBMX) in stimulating sperm motility have been compared, and we have found IBMX to be significantly more potent than the other three compounds, which did not exhibit significant differences in potency from each other.

The influence of in vitro caffeine treatment on human sperm morphology and fertilizing capacity

After publication in the literature that in vitro caffeine treatment causes damage of the normal shape of the sperm head and thereby decreases fertilizing capacity, we carried out a clinical and electron microscopic study to determine the influence of caffeine on the fertilizing capacity and sperm cell morphology. Sixty women (with infertile husbands) underwent artificial insemination by donor with frozen/thawed semen over a period of 12 months, using randomized addition of caffeine in alternate months. Fourteen women became pregnant during the 6 months they received caffeine-treated semen, whereas only 7 pregnancies occurred during the 6 months the women received semen without caffeine. Scanning electron microscopic examinations of fresh proven donor semen showed no morphologic changes caused by the in vitro caffeine treatment. However, quantitative morphologic analysis of the frozen/thawed semen was unsatisfactory because of the freezing technique and the masking effect of the protective medium. It is concluded that in vitro caffeine treatment of fertile donor semen does not damage the spermatozoa; furthermore, it seems to improve the fertilizing capacity.

Microcinematographic analysis of the motility of human spermatozoa incubated with caffeine

The effects of incubation with caffeine at final concentration of 0.5 and 5.0 mM for 30 min at ambient temperature were examined in three normal semen samples and three from asthenozoospermic men. A 50 frames/s microcinematographic analysis of the sperm motility was performed and two characteristic parameters of the trajectories, the progression velocity (Vp) and the amplitude of lateral head displacement (Ah), were measured. At the lower concentration (0.5 mM) no significant effects on the overall mean values (i.e. for all spermatozoa analyzed over the 6 samples) of Vp Ah were found. However, at 5.0 mM a significant reduction in the overall mean Vp was noted. The individual responses were variable between the 6 samples, but only in two of the asthenozoospermic samples and one normal ejaculate were the slow-swimming (less than 20 micrometer/s) spermatozoa accelerated by caffeine treatment. In other samples a reduction in the velocity of faster-swimming spermatozoa was observed. It would seem preferable to reserve caffeine treatment only for severe cases of asthenozoospermia where the distribution of sperm velocities of skewed towards low values.

Effect of temperature, nutrients, calcium, and cAMP on motility of human spermatozoa

The motility of human spermatozoa and its regulation were examined on cells isolated from other seminal components and purified into fractions of uniform progressive motility. The percent motile cells and estimates of their translational speed were determined by visual inspection, by stroboscopy, and by photon correlation spectroscopy; microcinematography and gradient centrifugation were occasionally used to clarify discrepancies. The motility of isolated spermatozoa could be maintained for periods up to 24 h at 4 or 37 degrees C; the presence of seminal fluid was not required and even provoked a reversible inhibition at 4 degrees C. Albumin facilitated cell movement between microscopic glass plates but had no effect on progressive motility per se, as evidenced by other techniques. During incubations of up to 2 h, progressive cell motility occurred independently of extracellular glucose and calcium but responded to variations in adenosine 3',5'-cyclic monophosphate and calcium. Dibutyryl cAMP increased forward motility, whereas ethyleneglycol-bis(beta-aminoethylether)-N,N'-tetraacetic acid reversibly immobilized the spermatozoa in a calcium-dependent manner; phosphodiesterase inhibition resulted in increased vibration of sperm heads without any effect on progressive motility. Longer incubation periods required the presence of extracellular nutrients. These experiments further demonstrate that several motility measuring techniques should be used in parallel to distinguish the various components of cell movement, to exclude aspecific effects, and to supplement the shortcomings of each individual technique. Such procedure could clarify the various discrepancies that have been reported so far and should lead to a better understanding of the regulation of human sperm motility.

Distribution of cyclic AMP in human seminal plasma and its relation to sperm progressive motility

Organelles and amorphous substance (pellet II) isolated from human seminal plasma contained 3'5' AMP (cyclic AMP, cAMP) in manifold smaller amounts than did the particle-free seminal plasma. The amount of cAMP associated with pellet II did not differ significantly between normospermic and oligozoospermic or teratozoospermic ejaculates. In analyses of split ejaculate fractions, the distribution of cAMP coincided with that of fructose and protein (but not with the Mg2+- and Ca2+-dependent ATPase activity or with zinc), indicating secretion of cAMP by the seminal vesicles. The distribution profiles of cAMP in the various ejaculate fractions were similar for particle-free seminal plasma and for pellet II material. The cAMP contents of the fractions were compared with sperm motility in the same fractions. An inverse relationship was found, with the first three fractions displaying higher sperm motility and the last three fractions higher cAMP content.

Effect of cAMP, Mn2+, and phosphodiesterase inhibitors on human sperm motility

The effects of cyclic adenosine monophosphate (cAMP), MnCl2, caffeine, and theophylline at concentrations of 10 mM on human sperm motility and forward migration in vitro were tested. cAMP was effective in activating human spermatozoal motility and forward migration after incubation with the spermatozoa for 3 hr or more and 5 hr, respectively, whereas caffeine and theophylline were effective in activating sperm motility after incubation with the spermatozoa for 1 hr or more. Caffeine and theophylline significantly activated sperm forward migration only after incubation with the sperm for 5 hr. MnCl2, a potent sperm adenylate cyclase activator, had no significant effect in improving human sperm motility and forward migration.