Polyamines protect porcine sperm from lipopolysaccharide-induced mitochondrial dysfunction and apoptosis via casein kinase 2 activation

Bacterial contamination is an inevitable issue during the processing of semen preservation in pigs. As a prototypical endotoxin from Gram-negative bacteria in semen, lipopolysaccharide (LPS) undermines sperm function during liquid preservation. Spermine and spermidine could protect cells against LPS-induced injury, and the content of spermine and spermidine in seminal plasma is positively correlated with sperm quality. Thus, the present study aimed to clarify whether addition of spermine or spermidine is beneficial to porcine semen preservation and able to prevent LPS-induced sperm damage. The supplementation of spermine and spermidine in the diluent resulted in higher sperm motility, viability, acrosome integrity, and mitochondrial membrane potential (ΔΨm) after preservation in vitro at 17 °C for 7 d (P < 0.05). LPS-induced sperm quality deterioration, ΔΨm decline, cellular adenosine-triphosphate depletion, mitochondrial ultrastructure abnormality, mitochondrial permeability transition pore opening, phosphatidylserine (PS) translocation, and caspase-3 activation (P < 0.05). Interestingly, spermine and spermidine alleviated the LPS-induced changes of the aforementioned parameters and mitigated the decrease in the microtubule-associated protein light chain 3-II (LC3-II) to LC3-I ratio. Meanwhile, the α and β subunits of casein kinase 2 (CK2) were detected at the connecting piece and the tail. Significantly, addition of 4,5,6,7-tetrabromobenzotriazole, a specific CK2 inhibitor, counteracted the beneficial effects of spermine and spermidine on sperm quality, mitochondrial activity, and apoptosis. Together, these results suggest that spermine and spermidine improve sperm quality and the efficiency of liquid preservation of porcine semen. Furthermore, spermine and spermidine alleviate LPS-induced sperm mitochondrial dysfunction and apoptosis in a CK2-dependent manner.

Short-Term Storage of Rooster Ejaculates: Sperm Quality and Bacterial Profile Differences in Selected Commercial Extenders

Bacterial contamination of semen has become an important contributor to the reduced shelf life of insemination doses in the poultry industry, which is why antibiotics (ATBs) are an important component of semen extenders. Due to a global rise in antimicrobial resistance, the aim of this study was to assess the efficiency of selected commercially available semen extenders to prevent possible bacterial contamination of rooster ejaculates. Two selected extenders free from or containing 31.2 µg/mL kanamycin (KAN) were used to process semen samples from 63 healthy Lohmann Brown roosters. Phosphate-buffered saline without ATBs was used as a control. The extended samples were stored at 4 °C for 24 h. Sperm motility, viability, mitochondrial activity, DNA integrity and the oxidative profile of each extended sample were assessed following 2 h and 24 h of storage. Furthermore, selective media were used to quantify the bacterial load and specific bacterial species were identified with matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry. The results indicate that semen extenders enriched with KAN ensured a significantly higher preservation of sperm quality in comparison to their KAN-free counterparts. Bacterial load was significantly decreased in diluents supplemented with ATBs (p ≤ 0.001); however, KAN alone was not effective enough to eradicate all bacteria since several Escherichia coli, Enterococcus faecalis, Enterococcus faecium and Micrococcus luteus were retrieved from samples extended in KAN-supplemented commercial extenders. As such, we may suggest that more focus should be devoted to the selection of an optimal combination and dose of antibiotics for poultry extenders, which should be accompanied by a more frequent bacteriological screening of native as well as extended poultry semen.

Methylprednisolone improves the quality of liquid preserved boar spermatozoa in vitro and reduces polymorphonuclear neutrophil chemotaxis and phagocytosis

After artificial insemination, immune cells such as polymorphonuclear neutrophils will be recruited into the genital tract and induce endometrial inflammation, adversely affecting the spermatozoa. This study aimed to analyze the effect of methylprednisolone (MPS) on boar spermatozoa quality of in vitro liquid preservation and chemotaxis and phagocytosis of polymorphonuclear neutrophils toward boar spermatozoa. Various concentrations of MPS were added to the extender and analyzed for their effects on spermatozoa motility, kinetic parameters, abnormality rate, total antioxidant capacity (T-AOC) levels, H₂O₂ content, mitochondrial membrane potential and acrosome integrity. Testing of MPS on chemotaxis and phagocytosis of polymorphonuclear neutrophils toward spermatozoa induced by lipopolysaccharide (LPS). The results showed that an extender containing 2 × 10^-7 mol/mL MPS was the most effective for preserving boar spermatozoa during in vitro liquid preservation at 17°C. It effectively improved spermatozoa motility, kinetic parameters, T-AOC levels, mitochondrial membrane potential and acrosome integrity, reducing the abnormality rate and H₂O₂ content. Meanwhile, the chemotaxis and phagocytosis of polymorphonuclear neutrophils toward spermatozoa under LPS induction were inhibited in a concentration-dependent manner. In conclusion, MPS has positive implications for improving in vitro liquid preserved boar spermatozoa quality, inhibiting chemotaxis and phagocytosis of polymorphonuclear neutrophils toward spermatozoa.

Mitochondria-Targeted Compounds to Assess and Improve Human Sperm Function

Significance: Currently 10%-15% of couples in reproductive age face infertility issues. More importantly, male factor contributes to 50% of these cases (either alone or in combination with female causes). Among various reasons, impaired sperm function is the main cause for male infertility. Furthermore, mitochondrial dysfunction and oxidative stress due to increased reactive oxygen species (ROS) production, particularly of mitochondrial origin, are believed to be the main contributors. Recent Advances: Mitochondrial dysfunction, particularly due to increased ROS production, has often been linked to impaired sperm function/quality. For decades, different methods and approaches have been developed to assess mitochondrial features that might correlate with sperm functionality. This connection is now completely accepted, with mitochondrial functionality assessment used more commonly as a readout of sperm functionality. More recently, mitochondria-targeted compounds are on the frontline for both assessment and therapeutic approaches. Critical Issues: In this review, we summarize the current methods for assessing key mitochondrial parameters known to reflect sperm quality as well as therapeutic strategies using mitochondria-targeted antioxidants aiming to improve sperm function in various situations, particularly after sperm cryopreservation. Future Directions: Although more systematic research is needed, mitochondria-targeted compounds definitely represent a promising tool to assess as well as to protect and improve sperm function. Antioxid. Redox Signal. 37, 451-480.

Coenzyme Q10 improves the quality of sheep sperm stored at room temperature by mitigating oxidative stress

The purpose of this experiment was to explore whether coenzyme Q₁₀ (CoQ₁₀ ) improves the quality of sheep semen stored at room temperature by attenuating oxidative stress. Semen was diluted without (control group), and with antioxidants (5, 50, 250, and 500 μmol/L CoQ₁₀ ). Sperm kinetic parameters and plasma membrane integrity were determined, and the reactive oxygen species (ROS), malondialdehyde (MDA), adenosine triphosphate (ATP), mitochondrial membrane potential (MMP), total antioxidant capacity (TAOC), catalase (CAT), and superoxide dismutase (SOD) activity were evaluated on the fifth day of semen preservation. The results showed that compared with the control group, the progressive motility in the 50 μmol/L group was higher (p < 0.05) within 2-5 days, and the plasma membrane integrity of sperm was higher in the 50 μmol/L group. The ROS content in the 5 and 50 μmol/L groups was reduced. The MDA level was reduced in the CoQ₁₀ supplementation groups (p < 0.05). Additionally, the CAT, SOD, TAOC, ATP and MMP levels in the 50 μmol/L group were higher than those in the control group (p < 0.05). In conclusion, CoQ₁₀ improved the quality of ram semen by alleviating oxidative stress, and 50 μmol/L CoQ₁₀ was the optimum concentration.

Cannabinoid signalling and effects of cannabis on the male reproductive system

Marijuana is the most widely consumed recreational drug worldwide, which raises concerns for its potential effects on fertility. Many aspects of human male reproduction can be modulated by cannabis-derived extracts (cannabinoids) and their endogenous counterparts, known as endocannabinoids (eCBs). These latter molecules act as critical signals in a variety of physiological processes through receptors, enzymes and transporters collectively termed the endocannabinoid system (ECS). Increasing evidence suggests a role for eCBs, as well as cannabinoids, in various aspects of male sexual and reproductive health. Although preclinical studies have clearly shown that ECS is involved in negative modulation of testosterone secretion by acting both at central and testicular levels in animal models, the effect of in vivo exposure to cannabinoids on spermatogenesis remains a matter of debate. Furthermore, inconclusive clinical evidence does not seem to support the notion that plant-derived cannabinoids have harmful effects on human sexual and reproductive health. An improved understanding of the complex crosstalk between cannabinoids and eCBs is required before targeting of ECS for modulation of human fertility becomes a reality.

Characterisation and localisation of the endocannabinoid system components in the adult human testis

Heavy use of cannabis (marijuana) has been associated with decreased semen quality, which may reflect disruption of the endocannabinoid system (ECS) in the male reproductive tract by exogenous cannabinoids. Components of ECS have been previously described in human spermatozoa and in the rodent testis but there is little information on the ECS expression within the human testis. In this study we characterised the main components of the ECS by immunohistochemistry (IHC) on archived testis tissue samples from 15 patients, and by in silico analysis of existing transcriptome datasets from testicular cell populations. The presence of 2-arachidonoylglycerol (2-AG) in the human testis was confirmed by matrix-assisted laser desorption ionization imaging analysis. Endocannabinoid-synthesising enzymes; diacylglycerol lipase (DAGL) and N-acyl-phosphatidylethanolamine-specific phospholipase D (NAPE-PLD), were detected in germ cells and somatic cells, respectively. The cannabinoid receptors, CNR1 and CNR2 were detected at a low level in post-meiotic germ cells and Leydig- and peritubular cells. Different transcripts encoding distinct receptor isoforms (CB1, CB1A, CB1B and CB2A) were also differentially distributed, mainly in germ cells. The cannabinoid-metabolising enzymes were abundantly present; the α/β-hydrolase domain-containing protein 2 (ABHD2) in all germ cell types, except early spermatocytes, the monoacylglycerol lipase (MGLL) in Sertoli cells, and the fatty acid amide hydrolase (FAAH) in late spermatocytes and post-meiotic germ cells. Our findings are consistent with a direct involvement of the ECS in regulation of human testicular physiology, including spermatogenesis and Leydig cell function. The study provides new evidence supporting observations that recreational cannabis can have possible deleterious effects on human testicular function.

Hexavalent chromium affects sperm motility by influencing protein tyrosine phosphorylation in the midpiece of boar spermatozoa

Hexavalent chromium reportedly induces reproductive toxicity and further inhibits male fertility in mammals. In this study, we investigated the molecular mechanism by which hexavalent chromium affects motility signaling in boar spermatozoa in vitro. The results indicated that Cr(VI) decreased sperm motility, protein phosphorylation, mitochondrial membrane potential (ΔΨm) and metabolic enzyme activity starting at 4μmol/mL following incubation for 1.5h. Notably, all parameters were potently inhibited by 10μmol/mL Cr, while supplementation with the dibutyryl-cAMP (dbcAMP) and the 3-isobutyl-1-methylxanthine (IBMX) prevented the inhibition of protein phosphorylation. Interestingly, high concentrations of Cr (>10μmol/mL) increased the tyrosine phosphorylation of some high-molecular-weight proteins in the principle piece but decreased that in the middle piece associated with an extreme reduction of sperm motility. These results suggest that chromium affects boar sperm motility by impairing tyrosine phosphorylation in the midpiece of sperm by blocking the cAMP/PKA pathway in boar sperm in vitro.