Expression of lactoferrin in the boar epididymis: effects of reduced estrogen

Lactoferrin: A glycoprotein that plays an active role in human health

Lactoferrin (Lf), existing widely in human and mammalian milk, is a multifunctional glycoprotein with many functions, such as immune regulation, anti-inflammation, antibacterial, antiviral, and antioxidant. These extensive functions largely attribute to its ability to chelate iron and interfere with the cellular receptors of pathogenic microorganisms and their hosts. Moreover, it is non-toxic and has good compatibility with other supplements. Thus, Lf has been widely used in food nutrition, drug carriers, biotechnology, and feed development. Although Lf has been continuously explored and studied, a more comprehensive and systematic compendium is still required. This review presents the recent advances in the structure and physicochemical properties of Lf as well as clinical studies on human diseases, with the aim of providing a reference for further research of Lf and the development of its related functional products.

Effect of lactoferrin on ram sperm motility after cryopreservation

Objective

The objective of this study was to analyse the differentially abundant proteins caused by freeze-thawing of ram sperm and explore candidate proteins of interest for their ability to improve ram sperm cryopreservation outcomes in vitro .

Methods

Sperm were from three mature Dorper. Fresh and frozen sperm proteins were extracted, and the differentially abundant proteins were analysed by mass spectrometry (MS). Among these proteins, lactoferrin（LTF) was selected to be added before cryopreservation. Next, sperm samples were diluted in Tris extender, with the addition of 0μg/ml,10 μg/ml, 100 μg/ml, 500 μg/ml, 1000 μg/ml of LTF. After thawing, sperm quality evaluated by motility, plasma membrane integrity, mitochondrial activity and reactive oxygen species (ROS).

Results

Cryopreservation significantly altered the abundance of 40 proteins; the abundance of 16 proteins was increased, while that of 24 proteins was decreased. Next, LTF was added to Tris extender applied to ram sperm. The results showed that sperm motility and plasma membrane integrity were significantly improved (p<0.05) by supplementation with 10 μg/ml LTF compared to those in the control group. There was no significant difference in mitochondrial activity between the 0μg/ml group and other groups (p>0.05). Supplementation of the cryoprotective extender with 10 μg/ml LTF led to decreased reactive oxygen species (ROS) levels compared with those in the control and other groups (p<0.05).

Conclusion

LTF is an important protein during cryopreservation, and the addition of 10 μg/ml LTF to a cryoprotective extender can significantly improve the function of frozen ram sperm.

Protein Identification of Spermatozoa and Seminal Plasma in Bottlenose Dolphin (Tursiops truncatus)

Proteins play an important role in many reproductive functions such as sperm maturation, sperm transit in the female genital tract or sperm-oocyte interaction. However, in general, little information concerning reproductive features is available in the case of aquatic animals. The present study aims to characterize the proteome of both spermatozoa and seminal plasma of bottlenose dolphins (Tursiops truncatus) as a model organism for cetaceans. Ejaculate samples were obtained from two trained dolphins housed in an aquarium. Spermatozoa and seminal plasma were analyzed by means of proteomic analyses using an LC-MS/MS, and a list with the gene symbols corresponding to each protein was submitted to the DAVID database. Of the 419 proteins identified in spermatozoa and 303 in seminal plasma, 111 proteins were shared by both. Furthermore, 70 proteins were identified as involved in reproductive processes, 39 in spermatozoa, and 31 in seminal plasma. The five most abundant proteins were also identified in these samples: AKAP3, ODF2, TUBB, GSTM3, ROPN1 for spermatozoa and CST11, LTF, ALB, HSP90B1, PIGR for seminal plasma. In conclusion, this study provides the first characterization of the proteome in cetacean sperm and seminal plasma, opening the way to future research into new biomarkers, the analysis of conservation capacity or possible additional applications in the field of assisted reproductive technologies.

Molecular Changes Induced by Oxidative Stress that Impair Human Sperm Motility

A state of oxidative stress (OS) and the presence of reactive oxygen species (ROS) in the male reproductive tract are strongly correlated with infertility. While physiological levels of ROS are necessary for normal sperm functioning, elevated ROS production can overwhelm the cell's limited antioxidant defenses leading to dysfunction and loss of fertilizing potential. Among the deleterious pleiotropic impacts arising from OS, sperm motility appears to be particularly vulnerable. Here, we present a mechanistic account for how OS contributes to altered sperm motility profiles. In our model, it is suggested that the abundant polyunsaturated fatty acids (PUFAs) residing in the sperm membrane serve to sensitize the male germ cell to ROS attack by virtue of their ability to act as substrates for lipid peroxidation (LPO) cascades. Upon initiation, LPO leads to dramatic remodeling of the composition and biophysical properties of sperm membranes and, in the case of the mitochondria, this manifests in a dissipation of membrane potential, electron leakage, increased ROS production and reduced capacity for energy production. This situation is exacerbated by the production of cytotoxic LPO byproducts such as 4-hydroxynonenal, which dysregulate molecules associated with sperm bioenergetic pathways as well as the structural and signaling components of the motility apparatus. The impact of ROS also extends to lesions in the paternal genome, as is commonly seen in the defective spermatozoa of asthenozoospermic males. Concluding, the presence of OS in the male reproductive tract is strongly and positively correlated with reduced sperm motility and fertilizing potential, thus providing a rational target for the development of new therapeutic interventions.

Effects of Estrogen Treatment on Aging in the Rat Epididymis

Previous studies from our laboratory demonstrated that estrogen signaling in the testis contributes to maintaining spermatogenesis in adult rats, and that estrogen treatment attenuated the age-associated decline in sperm production. The purpose of this study was to determine if epididymal function is also altered with age, and what effects estrogen treatment may have on the epididymis during aging. We compared untreated rats at 3 and 15 months of age to 18-month-old vehicle-treated and estrogen treated rats. In all four groups, tubule and lumen diameter of the cauda was significantly larger than more proximal regions of the epididymis. In the 3-, 15-, and 18-month-old treated animals, the epithelial cell height of the cauda was significantly shorter than that of more proximal regions. The caput cell height was shorter at 18 months compared to 3 months but this was not seen in estrogen treated animals. Thus, estrogen appears able to prevent some age related changes in epididymal morphology. Sperm transit time through the distal cauda was significantly delayed with aging. Estrogen treatment prevented this delay, indicating that sperm transit through the epididymis is an estrogen regulated function. Differences in estradiol and testosterone concentrations were observed between 3- and 15-month-old animals, but no further differences were noted between treated or untreated animals at 18 months. Interestingly, expression of androgen receptor and estrogen receptor alpha were similar between ages and treatments. Collectively, these results suggest epididymal morphology and function are affected by aging and estrogen treatment. Anat Rec, 302:1447-1457, 2019. © 2018 Wiley Periodicals, Inc.

Lactoferrin increases sperm membrane functionality of frozen equine semen

During cryopreservation, sperm was submitted to an increase in reactive oxygen species generation. This work aimed to improve the quality of frozen equine sperm after the addition of antioxidants lactoferrin (Lf) and catalase (Cat) to a freezing extender. Semen from six stallions was frozen with the extenders: F1) control, INRA 82 freezing extender, F2) F1 + 500 μg/ml Lf and F3) F1 + 200 IU/ml Cat. After thawing, sperm motility parameters, membrane functionality and integrity, and acrosome integrity and spontaneous acrosome-reacted sperm were evaluated with a computer-assisted sperm analysis, a hypoosmotic swelling test and epifluorescent microscopy, respectively. Nitrite, hydroperoxide and iron concentrations of frozen semen were measured with spectrophotometry. The percentage of functional membrane sperm treated with Lf was higher (50.7% ± 11.6%) compared to that of the control (37.6% ± 15.6%), while the iron (61.4 ± 11.6 vs 73.3 ± 13.8 mg/dl) and nitrite concentrations (16.3 ± 7.1 vs 25.9 ± 4.2 μM/μg protein) were lower, respectively (p < .05). Thus, it can be suggested that Lf protect stallion spermatozoon during freezing as it has increased the percentage of sperm with functional membrane and decreased the lipid oxidant agents.

Lactotransferrin in Asian elephant (Elephas maximus) seminal plasma correlates with semen quality

Asian elephants (Elephas maximus) have highly variable ejaculate quality within individuals, greatly reducing the efficacy of artificial insemination and making it difficult to devise a sperm cryopreservation protocol for this endangered species. Because seminal plasma influences sperm function and physiology, including sperm motility, the objectives of this study were to characterize the chemistry and protein profiles of Asian elephant seminal plasma and to determine the relationships between seminal plasma components and semen quality. Ejaculates exhibiting good sperm motility (≥65%) expressed higher percentages of spermatozoa with normal morphology (80.3±13.0 vs. 44.9±30.8%) and positive Spermac staining (51.9±14.5 vs. 7.5±14.4%), in addition to higher total volume (135.1±89.6 vs. 88.8±73.1 ml) and lower sperm concentration (473.0±511.2 vs. 1313.8±764.7×10⁶ cells ml⁻¹) compared to ejaculates exhibiting poor sperm motility (≤10%; P<0.05). Comparison of seminal plasma from ejaculates with good versus poor sperm motility revealed significant differences in concentrations of creatine phosphokinase, alanine aminotransferase, phosphorus, sodium, chloride, magnesium, and glucose. These observations suggest seminal plasma influences semen quality in elephants. One- and two-dimensional (2D) gel electrophoresis revealed largely similar compositional profiles of seminal plasma proteins between good and poor motility ejaculates. However, a protein of ∼80 kDa was abundant in 85% of ejaculates with good motility, and was absent in 90% of poor motility ejaculates (P<0.05). We used mass spectrometry to identify this protein as lactotransferrin, and immunoblot analysis to confirm this identification. Together, these findings lay a functional foundation for understanding the contributions of seminal plasma in the regulation of Asian elephant sperm motility, and for improving semen collection and storage in this endangered species.