Effect of extracellular adenosine 5'-triphosphate on cryopreserved epididymal cat sperm intracellular ATP concentration, sperm quality, and in vitro fertilizing ability

Influence of extracellular ATP on mammalian sperm physiology

In addition to its central role in cellular metabolism, adenosine 5'-triphosphate (ATP) is an important extracellular signalling molecule involved in various physiological processes. In reproduction, extracellular ATP participates in both autocrine and paracrine paths regulating gametogenesis, gamete maturation and fertilisation. This review focusses on how extracellular ATP modulates sperm physiology with emphasis on the mammalian acrosome reaction. The presence of extracellular ATP in the reproductive tract is primarily determined by the ion channels and transporters that influence its movement within the cells comprising the tract. The main targets of extracellular ATP in spermatozoa are its own transporters, particularly species-specific sperm purinergic receptors. We also discuss notable phenotypes from knock-out mouse models and human Mendelian inheritance related to ATP release mechanisms, along with immunological, proteomic, and functional observations regarding sperm purinergic receptors and their involvement in sperm signalling.

The multifaceted role of extracellular ATP in sperm function: From spermatogenesis to fertilization

Extracellular adenosine 5'-triphosphate (ATP) is a vital signaling molecule involved in various physiological processes within the body. In recent years, studies have revealed its significant role in male reproduction, particularly in sperm function. This review explores the multifaceted role of extracellular ATP in sperm function, from spermatogenesis to fertilization. We discuss the impact of extracellular ATP on spermatogenesis, sperm maturation and sperm-egg fusion, highlighting the complex regulatory mechanisms and potential clinical applications in the context of male infertility. By examining the latest research, we emphasize the crucial role of extracellular ATP in sperm function and propose future research directions to further.

Synergistic effect of extracellular adenosine triphosphate and quercetin on post-thaw quality and fertilization potential of Lohi ram sperm

This study determined the individual and combined effects of extracellular adenosine triphosphate (ATP) and quercetin (QUE) on the quality of post-thawed sperm and the fertilization potential of Lohi rams. In experiment 1, semen samples from four Lohi rams were pooled and extended with different concentrations of ATP or QUE (control; no ATP or QUE, 1 or 2 mM ATP and 10 or 20 μM QUE). In experiment 2, pooled semen samples were extended with various combinations of ATP and QUE (control; no ATP and QUE, 1 mM ATP + 10 μM QUE, 1 mM ATP + 20 μM QUE, 2 mM ATP + 10 μM QUE and 2 mM ATP + 20 μM QUE). All samples in both experiments were cryopreserved and analyzed for post-thawed sperm quality. In experiment 3, the best combination of ATP and QUE from experiment 2 was to extend semen, which was then used for laparoscopic insemination in estrus-synchronized ewes (n = 83). The results of experiment 1 showed that 1 mM ATP and 20 μM QUE treatments resulted in higher total motility, progressive motility, viability, plasma membrane intactness (PMI), and motion kinetics (VCL, VSL, VAP, LIN, and STR) compared to other treatments (p < 0.05). In experiment 2, the 1 mM ATP +10 μM QUE-treated group exhibited significantly higher total and progressive motility, PMI, and motion kinetics (VSL, VCL, VAP, STR, and BCF) compared to the control group (p < 0.05). In experiment 3, the fertilizing potential of sperms treated with 1 mM ATP +10 μM QUE was greater than that of untreated controls (58.1% vs. 27.5%, respectively, p-value = 0.012). In conclusion, the quality of post-thawed ram semen is enhanced when the extender is supplemented with extracellular 1 mM ATP and 20 μM QUE, whether used separately or in combination with 1 mM ATP and 10 μM QUE. Furthermore, the inclusion of 1 mM ATP and 10 μM QUE together in the extender significantly improves in vivo fertility in Lohi ram.

Saccharides Influence Sperm Quality and Expressions of Motility and Fertilization-Associated Genes in Cryopreserved Sperm of Pacific Abalone, Haliotis discus hannai

Pacific abalone, Haliotis discus hannai, is a highly commercial seafood in Southeast Asia. The present study aimed to determine the influence of saccharides and vitamins on post-thaw sperm quality, ATP content, fertilization capacity, hatching capacity, and mRNA content of motility and fertilization-associated genes of Pacific abalone. Sperm cryopreserved using saccharides improved the post-thaw sperm quality including motility, acrosome integrity (AI), plasma membrane integrity (PMI), and mitochondrial membrane potential (MMP). However, vitamins (l-ascorbic acid) did not result in any significant improvement in sperm quality. Sperm cryopreserved using saccharides also improved ATP content, DNA integrity, and mRNA content of motility and fertilization-associated genes of post-thaw sperm than sperm cryopreserved without saccharides. Among sperm cryopreserved using different saccharides, post-thaw sperm quality indicators (except PMI) and mRNA content of motility and fertilization-associated genes did not show significant differences between sperm cryopreserved using 3% sucrose (S) combined with 8% dimethyl sulfoxide (DMSO) and sperm cryopreserved using 1% glucose (G) combined with 8% ethylene glycol (EG). However, sperm cryopreserved using 3% S + 8% DMSO showed higher post-thaw sperm quality (motility: 58.4 ± 2.9%, AI: 57.1 ± 3.2%, PMI: 65.3 ± 3.3%, and MMP: 59.1 ± 3.2%), ATP content (48.4 ± 1.8 nmol/ml), and % DNA in tail (2.09 ± 0.20%) than sperm cryopreserved using other saccharides. When sperms were cryopreserved using 3% S + 8% DMSO, the mRNA content of motility (heat shock protein 70, HSP70; heat shock protein 90, HSP90; protein kinase A, PKA-C; axonemal protein 66.0, Axpp66.0; and tektin-4) and fertilization-associated (sperm protein 18 kDa, SP18 kDa) genes were higher than in sperm cryopreserved using other saccharides. However, changes in the mRNA contents of these genes were insignificant between sperm cryopreserved using 3% S + 8% DMSO and 1% G + 8% EG. Taken together, these results indicate that cryopreservation using 3% S + 8% DMSO can improve post-thaw sperm quality and mRNA contents better than other examined cryoprotectants. The present study suggests that 3% S + 8% DMSO is a suitable cryoprotectant for sperm cryopreservation and molecular conservation of this valuable species.

Quality of domestic cat semen collected by urethral catheterization after the use of different alpha 2-adrenergic agonists

OBJECTIVES

We compared the effects of two alpha (α)2-adrenergic agonists on semen traits.

METHODS

In this study, 13 adult domestic cats were divided into two experimental groups, according to the chemical ejaculation protocol used: the first group received medetomidine hydrochloride (100 µg/kg) and ketamine (5000 µg/kg); the second group received dexmedetomidine hydrochloride (25 µg/kg) and ketamine (5000 µg/kg), both by the intramuscular route.

RESULTS

The animals responded positively (P >0.05) to chemical collection. Seminal parameters evaluated included volume, sperm vigor, total motility, progressive motility, sperm concentration, and the structural and functional integrity of the plasma membrane; sperm morphology values did not differ between groups (P >0.05).

CONCLUSIONS AND RELEVANCE

The results indicated that dexmedetomidine is a more viable and economical alternative to medetomidine in domestic cats submitted to semen collection by urethral catheterization. Semen collection by urethral catheterization after using α2-adrenergic agonists is a recently developed technique in feline species that is considered to be quick and highly applicable to assisted reproduction programs in felids.

Recovery and cryopreservation of epididymal sperm from domestic cat using powdered coconut water (ACP-117c) and TRIS extenders

Cryopreservation of cats epididymal spermatozoa allows the conservation of the genetic material and the study of the cryogenic effect applied to the gametes of other felines. However, this biotechnique still presents variable results, being necessary the investigation of alternative extenders. Powdered coconut water (ACP-117c) has been efficient in the sperm freezing of several species and in the cat sperm refrigeration. Therefore, we aimed to evaluate the effect of the freezing stages and the quality of the cats' epididymal spermatozoa after thawing, using ACP-117c. Epididymides (n = 36) from 18 cats were processed using TRIS (n = 18) or ACP-117c (n = 18) for sperm recovery. The sperm were immediately evaluated. Then, this was cooled, glycerolized, frozen and thawed, and re-evaluated at each stage for sperm kinetics by Computer Assisted Semen Analysis, viability, functionality (HOST), mitochondrial activity (DAB) and morphology. There was a reduction in total motility and progressive motility after thawing in both groups, and TRIS was superior to ACP-117c. The curvilinear velocity reduced after thawing with ACP-117c. Viability decreased after glycerolization in TRIS. Although it also reduced after thawing in both groups, it was higher in TRIS. There was no change on HOST. Mitochondrial activity decreased during the cryopreservation steps for both extenders. Nevertheless, TRIS presented a higher percentage of spermatozoa from DAB class I and II after thawing. Morphology did not differ between extenders. Therefore, ACP-117c is an alternative for the recovery of cat epididymal spermatozoa; however, it is not efficient for freezing. Glycerolization and thawing are the most critical stages, regardless of the extender.

Extracellular ATPs produced in seminal plasma exosomes regulate boar sperm motility and mitochondrial metabolism

Artificial insemination using diluted semen with reduced presence of seminal plasma has been applied worldwide. Sperm stored in seminal plasma rather than diluted or removed show improvement in survival and motility. However, the link between seminal plasma and sperm remains poorly understood. This study focuses on the effect of extracellular adenosine triphosphate (exATP) produced by boar seminal plasma exosomes on sperm motility, as well as the underlying molecular mechanisms. The seminal plasma exosomes had an average diameter of 86.6 nm and showed universal exosome markers, such as heat shock protein 70 (HSP70) and CD63. Production of net ATP increased when exosomes were incubated with glucose and partly inhibited by a glycolytic inhibitor such as iodoacetate. Fresh boar sperm incubated with exATP significantly increased sperm motility and reduced apoptotic rate. Ser21 phosphorylation of glycogen synthase kinase 3α (inactivation) also significantly increased, consistent with the increase in mitochondrial transmembrane potential in the exATP-treated sperm. Moreover, exATP treatment increased the intracellular ATP (inATP) concentration and decreased the ADP/ATP ratio in boar sperm. Lactate content in the incubation medium was decreased, whereas lactate dehydrogenase activity in sperm was increased. This finding suggested that exATP could prompt lactate to produce inATP in order to sustain motility. The combined results indicate that exATP produced in seminal plasma exosomes may finely modulate mitochondrial metabolism to control sperm motility. The results can provide insights into semen dilution and artificial insemination.

Activation of adenosine monophosphate-activated protein kinase (AMPK) enhances energy metabolism, motility, and fertilizing ability of cryopreserved spermatozoa in domestic cat model

PURPOSE

Increasing intracellular energy storage by chemically activating adenosine monophosphate-activated protein kinase (AMPKα) prior to sperm cryopreservation may improve post-thawed sperm function. Using the domestic cat as a biomedical model, the objectives were to (1) confirm the expression of AMPKα and its regulatory kinases in epididymal spermatozoa and (2) assess the influence of AMPK activator, 5'-aminoimidasole-4-carboxamide-1-β-d-ribofuranoside (AICAR) on epididymal sperm function before and after cryopreservation.

METHODS

In study I, sperm samples of different qualities were obtained from cauda epididymides of domestic cats and evaluated for AMPKα expression. In study II, epididymal spermatozoa were equilibrated for either 30 or 60 min in the presence of 0 (control), 0.5, 2.0, and 5.0 mM AICAR and sperm functions were assessed before and after cryopreservation. In study III, epididymal spermatozoa were treated as in study II and evaluated for AMPKα signaling protein expressions (phospho-AMPKα Thr172 and GLUT1) as well as ATP levels.

RESULTS

AMPKα protein expression was higher in high-motility vs poor-motility samples. Thirty-minute equilibration with 0.5 mM AICAR improved motion characteristics and fertilizing ability of cryopreserved sperm to the control. Increased expressions of phospho-AMPKα Thr172 and GLUT1 as well as intracellular ATP level were confirmed in sperm samples equilibrated with 0.5 or 2.0 mM AICAR for 30 min.

CONCLUSIONS

Presence and role of AMPKα protein in cat regulating sperm function were demonstrated before and after cryopreservation. Findings could be used to potentially enhance cryopreserved sperm function in sub-fertile men.

Changes in sperm function and structure after freezing in domestic cat spermatozoa

Sperm cryopreservation allows for a long-term storage of genetic. However, changes due to factors as cold shock, osmotic and oxidative stress cause reduction in viability and fertilising ability of frozen/thawed spermatozoa. Therefore, evaluation of cryoinjury of cat spermatozoa is a key factor in achieving better cryopreservation results. This study analysed the changes in structural and functional after freezing in ejaculated domestic cats spermatozoa. Semen samples (n = 60) were analysed before and after freezing, progressive motility was determined with computer-assisted sperm analysis and viability, and acrosome intact spermatozoa, mitochondrial function and superoxide anion ( O 2 - ) were assessed by flow cytometry. The results demonstrated that cryopreservation induced changes in all sperm parameters (p < 0.05). Total sperm motility, viability, acrosome integrity and mitochondrial function of fresh samples were near to 80% and decrease near to 40% in frozen/thawed spermatozoa (p < 0.05); nevertheless, in contrast to all other sperm parameters, the sperm positive with O 2 - increased post/thawing (p < 0.05). In conclusion, changes in frozen/thawed spermatozoa could be related to the effect of oxidative stress due to the increase in the synthesis of O 2 - and a concomitant loss of functional competence. Therefore, the evaluation of these sperm parameters could contribute to complement the analysis of fresh or frozen semen used ART.

Developmental competence of cat (Felis domesticus) oocytes and embryos after parthenogenetic stimulation using different methods

The aim of this study was to compare the effects of various activating factors on feline oocytes. The study included activation within the ovary (natural), activation during in vitro maturation (spontaneous activation), chemical activation (ionomycin + 6-DMAP), activation by spermatozoa and injection (ICSI) and mechanical activation (sham ICSI). According to our results, parthenogenetic embryos could emerge at every step of in vitro embryo production (IVP) procedures. After oocyte collection, 6% of parthenogenetic embryos were observed, mainly at the 2-4-blastomere stages. After 24 h of in vitro maturation, parthenogenetic activation was observed in 7% of oocytes. Using ionomycin and 6-DMAP to artificially activate oocytes, 53% of cleaved embryos were obtained. The results after ICSI (54% cleaved embryos) were not significantly different from the results in Group III using chemical activation (53% cleaved embryos). But only after ICSI were blastocysts obtained (5/73.7%) as a result of in vitro culture. Moreover, embryos after ICSI were of the best morphological quality with minor levels of fragmentation evident in the embryos. After sham mechanical activation, 'sham ICSI', 8% of cleaved embryos were noted. Therefore, it is advised to maintain a negative control in parallel with each step of IVP techniques, to avoid misleading results. Chemical methods for artificial activation of feline oocytes are the most promising for application to the cloning and production of parthenogenetic embryos for experimental studies.

Beneficial effect of extracellular adenosine 5'-triphosphate treatment on the Indochinese leopard (Panthera pardus delacouri) sperm quality after cryopreservation

The Indochinese leopard (Panthera pardus delacouri) population, included in CITES Appendix I, has been declining for decades. Proper gamete preservation condition is critical for breeding programme management using artificial insemination or in vitro fertilization (IVF). The present study aimed at investigating the impact of post-thawing treatment of leopard semen with extracellular adenosine 5'-triphosphate (ATPe) on sperm quality (including morphological traits and ability to fertilize an oocyte). Semen from six adult male leopards was collected by electroejaculation (one ejaculation per cat). After the evaluation of the fresh sample quality, the semen was cryopreserved (10 × 10⁶ cells per straw; two straws per cat). After thawing, the sperm sample from the first straw of each cat was divided into three aliquots: control (no ATPe), supplemented with 1.0 or 2.5 mM ATPe that were evaluated for sperm quality at 10, 30 min and 3 hr post-thawing. The sperm sample from the second straw, supplemented with 0, 1.0 or 2.5 mM ATPe for 30 min, was assessed for IVF with domestic cat oocytes. Sperm quality (all metrics) was negatively affected by the cryopreservation process (p ≤ .05). However, the percentage of sperm motility, level of progressive motility and percentage of plasma membrane integrity did not differ (p > .05) among post-thawing groups. The sperm mitochondrial membrane potential was enhanced (p ≤ .05) by ATPe treatment (1.0 and 2.5 mM; 10 min to 3 hr of incubation). Furthermore, incubation of ATPe (1.0 and 2.5 mM) for 30 min could promote sperm velocity patterns (curvilinear velocity; VCL and straight line velocity; VSL) (p ≤ .05). The percentage of pronuclear formation and cleaved embryos was increased (p ≤ .05) after 1.0 ATPe treatment (49.8 ± 2.8; 45.9 ± 1.5) compared to 0 mM (41.4 ± 3.3; 38.9 ± 0.5) whereas the number of sperm binding/oocyte did not significantly differ among groups. In summary, we suggest that ATPe activated the velocity of Indochinese leopard sperm motility that may lead to faster sperm/oocyte binding and sperm penetration (factors of successful embryo development).