Calcium, magnesium, and zinc contents in organelles of prostatic origin in human seminal plasma

Infertility: Focus on the therapeutic potential of extracellular vesicles

Infertility is a well-known problem that arises from a variety of reproductive diseases. Until now, researchers have tried various methods to restore fertility, including medication specific to the cause, hormone treatments, surgical removals, and assisted reproductive technologies. While these methods do produce results, they do not consistently lead to fertility restoration in every instance. The use of exosome therapy has significant potential in treating infertility in patients. This is because exosomes, microvesicles, and apoptotic bodies, which are different types of vesicles, play a crucial role in transferring bioactive molecules that aid in cell-to-cell communication. Reproductive fluids can transport a variety of molecular cargos, such as miRNAs, mRNAs, proteins, lipids, and DNA molecules. The percentage of these cargos in the fluids can be linked to their physiological and pathological status. EVs are involved in several physiological and pathological processes and offer interesting non-cellular therapeutic possibilities to treat infertility. EVs (extracellular vesicles) transplantation has been shown in many studies to be a key part of regenerating different parts of the reproductive system, including the production of oocytes and the start of sperm production. Nevertheless, the existing evidence necessitates testifying to the effectiveness of injecting EVs in resolving reproductive problems among humans. This review focuses on the current literature about infertility issues in both females and males, specifically examining the potential treatments involving extracellular vesicles (EVs).

Using Small Non-Coding RNAs in Extracellular Vesicles of Semen as Biomarkers of Male Reproductive System Health: Opportunities and Challenges

Reproductive dysfunction and urogenital malignancies represent a serious health concern in men. This is in part as a result of the absence of reliable non-invasive tests of diagnosis/prognosis. Optimizing diagnosis and predicting the patient’s prognosis will affect the choice of the most appropriate treatment and therefore increase the chances of success and the result of therapy, that is, it will lead to a more personalized treatment of the patient. This review aims firstly to critically summarize the current knowledge of the reproductive roles played by extracellular vesicle small RNA components, which are typically altered in diseases affecting the male reproductive tract. Secondly, it aims to describe the use of semen extracellular vesicles as a non-invasive source of sncRNA-based biomarkers for urogenital diseases.

Nutritional supplementation of the pharmacotherapy of prostate diseases

Introduction: Nutritional supplementation is an integral part of modern pharmacotherapeutic strategies for prostate diseases with different levels of evidence for specific nutrients.

Provitamin A (beta-carotene), vitamin A (retinol) and prostate diseases. Their effects have not been sufficiently studied, and the available data are conflicting to recommend them as a nutritional supplement.

Vitamin E (tocopherol) and prostate diseases. Its effects have not been sufficiently studied, and the available data are conflicting to recommend it as a nutritional supplement.

Vitamin C (ascorbic acid) and prostate diseases. Its effects have not been sufficiently studied, and the available data are conflicted to recommend it as a nutritional supplement.

Vitamin K and prostate diseases. Its effects have not been sufficiently studied, and the available data are conflicted to recommend it as a nutritional supplement.

Vitamin D and prostate diseases. The evidence base of the vitamin D prostatotropic effects has been accumulated, which allows us to consider its deficiency replacement as an effective nutritional supplement in prostate diseases.

Omega-3 PUFAs and prostate diseases. They have universal physiological effects; however, the evidence base for their recommendation as a nutritional supplement for prostate diseases is still insufficient.

Zinc and prostate diseases. Positive effects of zinc on the prostate gland are known for a fact and allow us to recommend it as a nutritional supplement for prostate diseases.

Selenium and prostate diseases. The reliably proven positive effects of selenium on the prostate gland allow us to recommend it as a nutritional supplement for prostate diseases.

Magnesium and prostate diseases. Its effects have not been sufficiently studied, and the available data are conflicting to recommend it as a nutritional supplement.

Human prostasomes an extracellular vesicle - Biomarkers for male infertility and prostrate cancer: The journey from identification to current knowledge

Extracellular vesicles (EVs) are gaining attention among the cell biologists and researchers over the last two decades. Prostasomes are considered to be (Evs) secreted by prostate epithelial cells into the semen during emission or ejaculation. Prostasomes contain various proteins required for immune regulation namely, amino and dipeptidyl peptidase; endopeptidase (neutral); decay accelerating factor; angiotensin-converting enzyme. Sperm cells need a few prerequisites in order to fertilize the egg. The role of prostasomes in enhancing the male fertility was reviewed extensively throughout the manuscript. Also, prostasomes have an immunosuppressive, immunomodulatory, antibacterial role in the female reproductive tract, and in some cases they can be used as immunocontraceptive agent to regulate the fertility status. This review will give insights to many active researchers in the field of prostasomal research and male infertility/fertility research. This review will open many unanswered mechanisms of prostasomes with respect to structure-function analysis, fatty acids patterns in diagnosis as well as prognosis of male infertility/fertility. More scientific reports are in need to support the mechanism of prostasomes and its role in immunomodulation. The development of prostasomes as a biomarker for the prostate cancer is still miserable with a lot of controversial results by various researchers.

X-Ray Diffraction Study on Human Male Reproductive Tract and Semen

In the present study authors had separated testis, epididymis-caput, corpus, cauda, vas deferens, seminal vesicle, prostate gland and bulbourethral gland from human male reproductive tract, made it to ash form. Semen also underwent same procedure. All samples had undergone X-ray diffraction analysis.

Results

Results showed there where two distinct rings for each sample. We named it is “A” &” B”. Under “A” Barium silicate, Barium silicate hydrate and three metal complexes of copper, gold and zinc were seen. Under “B” Calcium silicate and calcium silicate hydrate were observed. Both “A” and “B” were seen throughout the length (expect for “A” is seminal vesicle) and in semen.

Conclusions

A tri metal complex of copper, gold and zinc is reported in this study, is first of its kind in Biology.

Exosomal particles secreted by prostate cancer cells are potent mRNA and protein vehicles for the interference of tumor and tumor environment

BACKGROUND

Remodeling of the tumor environment and the modulation of tumor associated non-malignant cells are essential events in tumor progression. Exosomes are small membranous vesicles of 50-150 nm in diameter, which are secreted into the extracellular space and supposedly serve as vehicles for signal and effector molecules to modulate adjacent target cells. We characterized the mRNA and protein composition as well as cellular functions of prostate cancer cell-derived exosomes.

METHODS

Exosomes were prepared from prostate cancer cell culture supernatant by ultracentrifugation and subsequently characterized by dynamic light scattering and electron microscopy. Exosomal mRNA and protein composition were analyzed by DNA microarrays and gel electrophoresis coupled with mass spectrometry. Physiological effects of exosomes were studied by means of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide and lactate dehydrogenase release cell assays. Using a SILAC approach, putative uptake of exosomal human proteins in canine cells and canine de novo synthesis of proteins specified by exosome-transferred human mRNA was analyzed in MDCK cells via mass spectrometry.

RESULTS

Preparations of exosomes revealed typical cup shaped particles of 150 nm in diameter. Analysis of mRNA and protein composition of exosomes exhibited a wide range of mRNA and protein species. Interestingly, the packaging of at least small proteins into exosomes was apparently unspecific, as shown with the example of two model proteins. In cell culture incubation experiments exosomal preparations of prostate cancer cells caused anti-proliferative effects. MS analysis revealed the uptake of exosomal human proteins into canine cells after 6 hr of incubation.

CONCLUSIONS

The results reveal a distinct exosomal functionality in the modulation of the prostatic tumor adjacent environment. The multitude of translocated factors implies the induction of numerous effects in tumor-associated target cells, including impact on cellular growth.

Prostasomes: Their Characterisation: Implications for Human Reproduction: Prostasomes and Human Reproduction

The prostate is a principal accessory genital gland that is vital for normal fertility. Epithelial cells lining the prostate acini release in a defined fashion (exocytosis) organellar nanosized structures named prostasomes. They are involved in the protection of sperm cells against immune response in the female reproductive tract by modulating the complement system and by inhibiting monocyte and neutrophil phagocytosis and lymphocyte proliferation. The immunomodulatory function most probably involves small non-coding RNAs present in prostasomes. Prostasomes have also been proposed to regulate the timing of sperm cell capacitation and induction of the acrosome reaction, since they are rich in various transferable bioactive molecules (e.g. receptors and enzymes) that promote the fertilising ability of sperm cells. Antigenicity of sperm cells has been well documented and implicated in involuntary immunological infertility of human couples, and antisperm antibodies (ASA) occur in several body fluids. The propensity of sperm cells to carry attached prostasomes suggests that they are a new category of sperm antigens. Circulating human ASA recognise prostasomes, and among 12 identified prostasomal antigens, prolactin- inducible protein (95 %) and clusterin (85 %) were immunodominant at the expense of the other 10 that were sporadically occurring.

Prostasomes of canine seminal plasma - zinc-binding ability and effects on motility characteristics and plasma membrane integrity of spermatozoa

Prostasomes are small lipid membrane-confined vesicles that are involved in various fertilization-related processes. The aim of this study was to demonstrate canine seminal plasma prostasomes' ability to bind zinc ions, as well as examining their effects on sperm motility characteristics and plasma membrane integrity during cold storage. Ejaculates, collected from five cross-bred dogs (n = 50), were subjected to ultracentrifugation followed by gel filtration (GF) on a Superose 6 column. Prostasomes appeared as a single fraction in the elution profile. Transmission electron microscopy (TEM) analysis of canine prostasomes revealed the presence of membrane vesicles with diameters ranging from 20.3 to 301 nm. The zinc-affinity chromatography on a Chelating Sepharose Fast Flow - Zn(2 +) showed that from 93 to 100% of the prostasome proteins bind zinc ions (P(+) Zn). SDS-PAGE revealed that canine P(+) Zn comprised four protein bands, with low molecular weights (10.2-12 kDa). We have also shown a positive effect of prostasomes (p < 0.05), especially variant B (2% of total seminal plasma protein) on canine sperm motility parameters after 2 h storage at 5°C (TMOT%, 44.75 ± 5.18) and PMOT%, 12.42 ± 1.59) and VAP, VSL, VCL, when compared with Control (TMOT%, 7.30 ± 1.41 and PMOT%, 1.70 ± 0.42). Higher percentage of spermatozoa with intact plasma membrane (SYBR/PI dual staining) and intact acrosome (Giemsa stained), after 2 h storage at 5°C, was showed, in variant A (1.5% of total seminal plasma protein) and B, when compared with Control and variant C (2.5% of total seminal plasma protein). The prostasomes' effect on motility and plasma membrane integrity of canine cold-stored spermatozoa may be related to their ability to bind zinc ions and regulate their availability to the sperm.

Impact of Seminal Chemical Elements on the Oxidative Balance in Bovine Seminal Plasma and Spermatozoa

Mutual relationships between selected chemical elements (Na, K, Fe, Cu, Mg, and Zn), basic motility characteristics (motility and progressive motility), and markers of the oxidative balance (superoxide dismutase, catalase, glutathione, albumin, and malondialdehyde) were investigated in bovine seminal plasma and spermatozoa. Computer assisted sperm analysis was used to assess the motility parameters; mineral concentrations were determined by the voltammetric method and flame absorption spectrophotometry; antioxidants and malondialdehyde were evaluated by UV/VIS spectrophotometry. Concentrations of chemical elements in both seminal fractions were in the following descending order: Na > K > Zn > Mg > Fe > Cu. Higher amounts of all minerals and nonenzymatic antioxidants were detected in the seminal plasma (P < 0.01; P < 0.001), while higher MDA concentration and activity of enzymatic antioxidants were recorded in the cell lysates (P < 0.01; P < 0.001). Na, Fe, Cu, Mg, and Zn were positively correlated with the motility and antioxidant parameters (P < 0.05; P < 0.01; P < 0.001). Inversely, K exhibited the positive associations with malondialdehyde (P < 0.05). This study demonstrates that most chemical elements are integral components of bovine semen and are needed for the protection against oxidative stress development.

Prostasomes are mediators of intercellular communication: from basic research to clinical implications

Prostasomes are nanosized microvesicles secreted by acinar epithelial cells of the prostate gland. Furthermore, they are intracellular microvesicles inside another larger vesicle, a so-called storage vesicle, equivalent to multivesicular bodies of late endosomal origin. Prostasomes are thought to play an important role in intercellular communication by direct interaction primarily between the immobile acinar cells of the prostate gland and the mobile spermatozoa. Prostasomes transfer not only membrane components but also genetic material to spermatozoa. They are rich in various transferable bioactive molecules (e.g., receptors and enzymes) that promote the fertilizing ability of spermatozoa. In this review, the pleiotropic biological effects of prostasomes that are relevant for successful fertilization will be discussed. The ability to synthesize and export prostasomes to the extracellular space is observed not only in normal prostate epithelial cells but also in malignant prostate cells. Release of prostasomes by prostate cancer cells suggests a role in malignant cell growth and proliferation. These findings may provide new therapeutic and diagnostic strategies.

Ca2+ signaling tools acquired from prostasomes are required for progesterone-induced sperm motility

Progesterone-induced calcium ion (Ca2+) signals in the neck region of sperm play a pivotal role in promoting sperm motility. Here, we show that a long-lasting Ca2+ signal required for sperm motility in response to progesterone depends on their pH-dependent fusion with prostasomes, which are small vesicles secreted by the prostate. We found that prostasome fusion led to the transfer of progesterone receptors, cyclic adenosine diphosphoribose (cADPR)-synthesizing enzymes, ryanodine receptors (RyRs), and other Ca2+ signaling tools from prostasomes to the sperm neck. Progesterone-induced sperm motility relied on cADPR-mediated Ca2+ mobilization through RyR located on acidic Ca2+ stores, followed by Ca2+ entry through store-operated channels. Treatment of prostasome-fused sperm with a cADPR antagonist or fusion with prostasomes in which type 2 RyR was depleted resulted in low fertilization rates, reduced sperm motility, or both. Thus, we conclude that sperm motility depends on the acquisition of Ca2+ signaling tools from prostasomes.

Prostasomes--their effects on human male reproduction and fertility

The prostate is a glandular male accessory sex organ vital for normal fertility. It provides the prostatic component of seminal plasma which nourishes and protects sperm following ejaculation. Prostasomes are small (40-500 nm) membrane-bound vesicles produced by epithelial cells lining the prostate acini and are a component of prostatic secretions. Although the existence of these particles has been known for many years, their full function and relevance to reproductive health are largely unknown. Proteomic studies have shown a wide range of proteins (enzymes, structural proteins and novel, unannotated proteins) present in or on the surface of prostasomes providing them with a diverse nature. Interestingly prostasomes are able to fuse with sperm, this event and the associated transfer of proteins lies at the heart of many of their proposed functions. Sperm motility is increased by the presence of prostasomes and their fusion prevents premature acrosome reactions. Prostasomes have been shown to aid protection of sperm within the female reproductive tract because of immunosuppressive, antioxidant and antibacterial properties. Clinically these functions imply a role for prostasomes in male factor infertility. However, the very functions that promote fertility may have negative connotations in later life; recent work has suggested that prostasomes are involved in prostate cancer. Clearly more work is needed to clarify the role of these novel particles and their impact on men's health.

The Janus-faced nature of prostasomes: their pluripotency favours the normal reproductive process and malignant prostate growth

Prostasomes are submicron secretory granules synthesized, stored and secreted by the epithelial cells of the human prostate gland. They are membrane-surrounded also in their extracellular appearance and the membrane architecture is composite. They are believed to be life-giving and act as protectors of the spermatozoa in the lower and upper female genital tract on their way to the ovum. Hence, the prostasomes are immunosuppressive and inhibitory of complement activation. Further, they promote sperm's forward motility and have antioxidant and antibacterial capacities. The prostasomes with their many composite abilities seem to turn against the host cell after the age of 50 y being conducive to the transition of the normal prostate epithelial cell into a neoplastic cell and therewith lay the foundations of the very high prevalence of prostate cancer of men of more than 50 y of age.

Prostasomes as zinc ligands in human seminal plasma

Prostasomes are small vesicles, containing zinc, secreted by prostate in human seminal plasma and showing a physiological role on sperm properties. In this study, the possible correspondence between prostasomes and a prostatic high molecular weight protein complex, recently indicated as zinc ligand, has been investigated. Isolated prostasomes, examined by scanning electron microscopy, were dialysed to evaluate their zinc binding capacity. Furthermore, seminal plasma Sephadex G-75 elution was carried out before and after prostasome removal. Prostasome preparations, containing typical vesicles of 50-500 nm, showed a positive correlation between their zinc and protein levels. They were able to take up zinc against gradient. Furthermore, the seminal zinc amount, bound to the high molecular weight proteins, was strongly reduced in the free-prostasome sample with respect to the total seminal plasma. This study suggested the correspondence between the prostasomes and a high-sized zinc ligand complex of prostatic origin. Therefore, it demonstrated, for the first time, the zinc binding capacity of prostasomes, a new property which could be related to their biological functions.

Role of human prostasomes in the activation of spermatozoa

Prostasomes are small vesicles of prostatic origin contained in human semen. Their composition is peculiar under many aspects. Cholesterol is abundant and many proteins are endowed with enzymatic or other activities. The function of prostasomes has been amply debated and several hypotheses have been put forward. The liquefaction of semen, spermatozoa motility, antibacterial activity and immunological functions have been related to prostasomes. Under certain aspects, prostasomes resemble synaptosomes. The fusion of prostasomes to spermatozoa enriches spermatozoa with cholesterol and causes bursts of cytoplasmic sperm calcium. The interaction of spermatozoa and prostasomes should be limited to vagina since prostasomes are immobile and do not follow spermatozoa in the superior female genital tract. Calcium bursts would increase spermatozoa motility, where cholesterol would decapacitate spermatozoa, so preventing untimely activation. Since spermatozoa receive many different molecules from prostasomes, additional effects are also possible. Prostasomes makes spermatozoa more apt to be activated by progesterone in the proximity of the ovum. Therefore, the fusion between spermatozoa and prostasomes would influence spermatozoa behaviour under many aspects and might be relevant for fecundation. The richness of molecular species in prostasomes is amazing and these small vesicles are expected to lead to many more discoveries in the field of human reproduction.

Association between captopril, other antihypertensive drugs and risk of prostate cancer

BACKGROUND

There has been some debate on the existence of an association between hypertension, antihypertensive medications and cancer risk.

METHODS

We performed a nested case-control study to assess the association between the risk of prostate cancer and the use of the angiotensin converting enzyme (ACE)-inhibitor captopril, and other antihypertensive drugs. We used data from the General Practice Research Database in UK.

RESULTS

We found an incidence rate of prostate cancer of 1.61 per 1,000 person-years among male patients aged 50-79 years old. Patients with a history of benign prostatic hyperplasia and/or prostatism carried a two-fold greater risk of prostate cancer than those without such antecedents. None of the other studied co-morbidities were associated with prostate cancer. We found that users of captopril had a relative risk of 0.7 (95% CI: 0.4-1.2) to develope prostate cancer. None of the other studied individual ACE-inhibitors shared a similar effect with the one observed for captopril.

CONCLUSIONS

No clear association was apparent between the use of antihypertensive drugs and prostate cancer. However, specific focus on users of captopril showed a lower risk of subsequent prostate cancer. Further research is needed to explore this association.

Ultrastructure of the secretion of prostasomes from benign and malignant epithelial cells in the prostate

BACKGROUND

Prostate epithelial cells are producing, among other things, a fluid secretion containing small bodies, the prostasomes. The mechanism of synthesis of the prostasomes is not known in details, neither is it known whether the mode of prostasome production changes at a neoplastic transformation of the prostate cells. Due to the small size of the prostasomes, we have used electron microscopy for evaluating the production and distribution of prostasomes in benign and neoplastic cells of the prostate.

METHODS

Benign and neoplastic areas in plastic embedded core biopsy specimens of prostate tissue were identified, and secreting cells were selected. The corresponding areas on the plastic blocks were further processed for examination in the electron microscope.

RESULTS

The electron microscopical examination showed that the secretory machinery was similar in both types of tissue. Thus, in both benign and well-differentiated neoplastic cells studied, the formation of storage vesicles in the Golgi areas was similar, the content of the vesicles appeared similar, the structure and distribution of prostasomes were alike, and in both benign and malignant tissue, the secretion in the gland ducts showed the same appearance with many prostasomes.

CONCLUSION

We conclude that cells in benign prostate tissue and cells in well-differentiated prostate carcinoma show great similarities in synthesis, storage, and release of prostasomes. However, this does not exclude the presence of other changes, for instance biochemical ones, in the prostasomes.

Hydrodynamic radii and lipid transfer in prostasome self-fusion

The characteristics of human prostasomal vesicles have been investigated by three methods, namely, dynamic light scattering, transfer of a lipophylic fluorescent dye (R18), and electron microscope appearance. The vesicle preparations were stable for a long time and their diameters were in the range of 200 nm. The exposure to acidic pH values (about 5) increased both particle radii and the transfer of R18. The microscopic appearance was also affected by the pH value. We infer that these changes are due to a self-fusion of prostasome vesicles; this fusion is protein-dependent since various methods used by us and able to affect the protein component of membranes (boiling, extraction of lipid and liposome preparation, treatment with pronase) all abolished the effect seen at pH 5 on intact particles.

Fatty acid pattern of human prostasome lipid

Prostasomes are organelles of prostatic origin found in human semen. Their average diameter is about 150 nm and they appear as a lipoprotein membrane surrounding less organized material. Their lipid composition is peculiar, having much cholesterol and sphingomyelin. On the other hand, many of their proteins possess catalytic activity and are involved in the immune response. In previous work, we have shown that prostasomes may fuse to sperm at slightly acidic pH values, thereby modifying the composition of the sperm plasma membrane. In this paper, we examine the fatty acid pattern of prostasome lipid and find that it is completely different from that of sperm membrane lipid. Polyunsaturated phosphatidylcholines, common in sperm membrane, are rare in prostasome. Therefore, the fusion between prostasomes and sperm should stabilize sperm plasma membrane by enriching it in cholesterol, sphingomyelin, and saturated glycerophospholipid. This would prevent the untimely occurrence of the acrosome reaction.

High resolution 1H NMR spectroscopic studies on dynamic biochemical processes in incubated human seminal fluid samples

High resolution 600 MHz 1H NMR spectroscopy was used to investigate the changes in biochemical composition of whole human seminal fluid (SF) and an artificial mixture of prostatic (PF) and seminal vesicle fluid (SVF). A variety of time-related biochemical changes were monitored simultaneously and non-invasively in SF, including enzymatic hydrolysis of phosphorylcholine to choline and polypeptides to amino acids. The fastest NMR-observable reactions in SF were the conversion of phosphorylcholine to choline (t1/2 approximately equal to 9 min) and uridine-5'-monophosphate (UMP) to uridine (t1/2 < 2 min). UMP has not previously been detected in SF because of its rapid hydrolysis. Artificial mixtures of separately obtained prostatic and SVF showed very similar biochemical changes to those observed in whole SF. Addition of EDTA to SF incubated for 2 min post ejaculation strongly inhibited peptide hydrolysis. Zn2+, present in whole SF was shown to be non EDTA-chelatable 2 min after ejaculation, whereas after 7 min, a singlet signal from the ethylenic protons of the Zn-EDTA2- complex was clearly observed which remained constant after 7 min. This indicates that soon after ejaculation (< 5 min) Zn2+ is immobilised in a macromolecular complex which is rapidly broken down by proteolytic enzymes, the released Zn2+ then being free to react with EDTA. Mg- and Ca-EDTA2- complexes were observed at 2 min and remained constant (at 1.4 and 2.1 mM, respectively) throughout the entire time course of the experiment. These studies cast new light on the time-related biochemical changes occurring in the post-ejaculatory SF which may have an important role in reproductive function.

Prostasomes are neuroendocrine-like vesicles in human semen

BACKGROUND

Prostasomes are prostate-derived organelles that exist extracellularly in human seminal plasma.

METHODS

In this study, we have investigated and characterized human prostasomes with regard to their contents of synaptophysin, members of the chromogranin family, and some neuropeptides.

RESULTS

By radioimmunoassay measurement and electron microscopy we show the presence of the neuroendocrine markers chromogranin B, neuropeptide Y, and vasoactive intestinal polypeptide in about equimolar amount in human prostasomes and chromogranin A in about 2% of that amount. To our knowledge, such a high ratio of chromogranin B to chromogranin A has never before been observed. The membrane-bound protein synaptophysin, a well-established immunocytochemical marker for neuroendocrine cells and neurones, was also detected. Hence, we show that synaptophysin could be used as a marker for intact prostasomes.

CONCLUSIONS

The presence of synaptophysin has recently been shown in the serotonincontaining vesicles in platelets. A protein with a similar structure denoted granulophysin has been found in granulocytes and prostasomes. It is suggested that synaptophysin and granulophysin molecules are members of a family of proteins, maybe expressed in all cells that have regulated release of granule content. Our presented data indicate a neurotransmittor function of the prostasomes. The target cells are however not known but could be either the spermatozoa, the epithelial mucous cells of the uterus or tubas or perhaps the ovum.

Interaction between prostasomes and spermatozoa from human semen

Prostasomes are prostate-derived organelles that occur freely in human seminal plasma. They promote forward motility of spermatozoa probably by closely interacting with them in an unknown manner. We have studied the interaction between human prostasomes and spermatozoa by applying them as two separate samples in free-zone electrophoresis. During the run these samples approached each other and finally fused into one single peak that was not further dissociated. Both the spermatozoa and prostasomes displayed a net-negative surface charge, the latter being less negative. This discrepancy in charge was even more pronounced by pretreatment of prostasomes with neuraminidase, which, however, did not affect the interaction. This implies a strong interaction of a probable hydrophobic character between cells and organelles. The presence of prostasomes and spermatozoa in the fused, single peak was confirmed by transmission electron microscopy. Evidence for interaction was apparent in transmission electron microscopy after embedding in a hydrophilic, but not in a hydrophobic, resin. This observation supports the view that the bonds between prostasomes and spermatozoa are of hydrophobic character. This type of interaction enables the prostasomes to act in close vicinity to spermatozoa and may create the prerequisites for a proper microenvironment of the spermatozoa favoring their forward motility.

Human prostasome membranes exhibit very high cholesterol/phospholipid ratios yielding high molecular ordering

Lipid analysis and ESR studies were carried out on prostasomes isolated from human semen. Cholesterol plus phospholipids amounted to approximately 0.80 mumol per mg protein with a striking quantitative domination of cholesterol over the phospholipids, the molar ratios of cholesterol/sphingomyelin/glycerophospholipids being 4:1:1. Saturated and monounsaturated fatty acids were dominating both in the glycerophospholipids and in sphingomyelin. The order parameters, S, deduced from ESR spectra of spin-labelled fatty acids incorporated into prostasome membranes order parameters, S, deduced from ESR spectra of spin-labelled fatty acids incorporated into prostasome membranes were very high, viz. 0.75 for 5-doxylstearic acid and 0.30 for 16-doxylstearic acid at 25 degrees C. Slightly lower values were obtained for the spin-labelled fatty acids when they were incorporated into dispersions of extracted prostasome lipids or into synthetic lipid mixtures of similar composition. The highly ordered lipids in the prostasome membrane thus seemed to be minimally perturbed by proteins in the membrane and ESR spectra showed no signs of immobilized lipids.

Effect of modulators on prostasome membrane-bound ATPase in human seminal plasma

The Mg2+- and Ca2+-dependent ATPase system in human seminal fluid is linked to membranes encasing small organelles denoted 'prostasomes'. This activity was completely pelleted after ultracentrifugation at 105,000 X g, provided the seminal plasma was diluted 1:10. On the contrary, prostatic acid phosphatase activity remained in the supernatant and was inhibited to about 75% by tartrate (0.5 mmol l-1) contrasting with the ATPase system that was not inhibited. Calmodulin, in the concentration interval 0.30-0.90 mumol l-1, did not further activate the ATPase system. Calmidazolium, which is a highly lipophilic substance, was a competitive inhibitor of the Mg2+- and Ca2+-dependent ATPase and half maximal inhibition was attained at 2-3 mumol l-1 calmidazolium. This inhibition was antagonized to a moderate degree (25%, P less than 0.02) by calmodulin, 0.60 mumol l-1. Quercetin, at concentrations of 30-60 mumol l-1, did not influence the prostasome membrane ATPase in any direction. Oleate was an inhibitor of the ATPase system at any concentration up to 50 mumol l-1. This inhibition was not counteracted to an appreciable extent by calmodulin. These results displayed a pattern giving support to the view that the Mg2+- and Ca2+-dependent ATPase of the prostasome membrane may be the molecular basis for vectorial transport of Ca2+ into prostasomes.

The prostasome: its secretion and function in man

An intact organelle, the prostasome, is secreted by the acinar epithelial cell of the human prostate gland. The ultrastructural location of the prostasome is within membrane-bound storage vesicles in the epithelial cells. Prostasomes are delivered into the glandular lumen by an exocytotic event, which is preceded by fusion of adjacent membranes belonging to the storage vesicle and the epithelial cell. Alternatively, the storage vesicle can be translocated in toto from the cell interior into the acinar lumen through the plasma membrane. This latter event has been designated diacytosis. Both phenomena seem to occur with approximately equal frequency in the human prostate gland. An ATPase system that is Mg2+ and Ca2+-dependent is firmly linked to the membranes encasing the prostasomes. The ATPase system may be the molecular basis for vectorial transport of calcium into these organelles. Also a protein kinase activity is located in the membranes. An increase in membrane thickness was observed on phosphorylation. The physiologic function of the prostasomes is not known. They may be important for promoting forward motility 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.

Uridine, xanthine, and urate contents in human seminal plasma

Levels of uridine, xanthine, and urate in the seminal plasma of 73 men with various infertility problems as well as 11 previously fertile men after vasectomy were estimated. Very high concentration (in the mmolar range) compared with other body fluids were recorded for uridine and xanthine, while urate was in about equimolar concentration to that in the serum. Both uridine and xanthine mean values were significantly increased in vasectomized men compared with normal men; otherwise, there was a wide overlapping of the mean values of these two compounds between the two groups. The mean value of urate was maintained at a rather constant level in the two groups. Analysis of "split" fractions favors an origin from prostatic fluid for xanthine and urate and from the seminal vesicles for uridine. Uridine was positively correlated to both fructose and xanthine in oligozoospermic men, to only xanthine in normal men, and negatively to urate in vasectomized men. Urate and xanthine correlated positively in normal and oligozoospermic men. Positive correlations were also observed for xanthine and fructose in oligozoospermic men and for urate and sperm concentration in normal men.

A zinc-dependent peptidase in prostatic organelles present in seminal plasma

The electrophoretic seminal plasma protein pattern changes obviously within a few hours if the plasma is not frozen after the ejaculation. Mainly cathodal proteins disappear. Addition of serine protease inhibitors has no apparent affect, but o-phenanthroline markedly retards the conversions seen on electrophoresis. The subcellular organelles in seminal plasma are shown to contain a zinc ion dependent peptidase with optimal activity at pH 7.8. Estimations of enzyme activity may be performed using the elastase substrates n-tert butyloxycarbonyl-L-alanine-paranitrophenylester (Boc(Ala)) and succinyl(alanine)3-paranitroanilide (Suc(Ala)3pNA). The enzyme is inactivated by addition of o-phenanthroline and is completely reactivated by the addition of zinc ions.

Promotive effect on human sperm progressive motility by prostasomes

Seminal plasma constituents were separated on Sephadex G200 gel columns. The column eluate was analysed with regard to protein content, ATPase activity and promotive activity on sperm progressive motility. Two different chromatographic fractions were also subjected to electron microscopy after sedimentation by preparative ultracentrifugation. A maximum promotive value on sperm progressive motility coincided with a maximum ATPase activity value in a single peak from seminal plasma eluted first on the column and containing less protein than the other peaks appearing later in the chromatogram. This first peak was the only one containing ATPase activity and membrane-surrounded organelles named prostasomes. Other peaks, rich in protein but lacking ATPase and prostasomes, displayed a moderate and rather irregular pattern in reference to promotive activity on sperm progressive motility. Evidence is given that the positive effect by prostasomes is specific on sperm progressive motility. Hence, procedures aiming at a change of membrane integrity of the prostasomes resulted in diminished effects on sperm progressive motility. This could be explained by a probable dissipation of the electrochemical gradient of calcium ions.

Stimulation of sperm progressive motility by organelles in human seminal plasma

A simple method for objective determination of sperm progressive motility is described. Comparisons were made between results with this method and subjective grading of motility. Although congruence between the two methods was demonstrated, the subjective evaluation had obvious disadvantages. In suspensions of NaCl-washed spermatozoa, seminal plasma was required for progressive motility. Various isotonic salt solutions without seminal plasma were ineffective in this respect. Washed spermatozoa, however, were always motile in a medium consisting of pellet II, obtained from ultracentrifugation of human seminal plasma, thoroughly mixed with isotonic NaCl solution. The progressive sperm motility was two to three times as great in that medium as in seminal plasma mainly devoid of organelles. Magnesium, calcium and zinc ions, in the presence of seminal plasma, could exert stimulatory and inhibitory effects on sperm progressive motility, depending on the concentration of each divalent cation. Magnesium gave the greatest stimulatory and zinc the greatest inhibitory effect.

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.