Characterization and identification of extracellular vesicles-coupled miRNA profiles in seminal plasma of fertile and subfertile rabbit bucks.

Seminal plasma (SP) provides essential nutrients, transport, and protection to the spermatozoa during their journey through the male and female reproductive tracts. Extracellular vesicles (EVs) are one of the main components of the SP with several biomolecular cargoes, including miRNAs, that can influence spermatozoa functions and interact with the cells of the female reproductive tract. This study aimed to isolate, characterize, and identify the miRNA expression profiles in the SP-EVs isolated from fertile (F) and subfertile (S) rabbit bucks that could serve as fertility biomarkers. In this study, the methods to isolate and identify EVs including exosomes, from SP of 3 F and S bucks have been developed. Ultracentrifugation and size exclusion chromatography analysis were using to isolate EVs from SP of F and S males that were qualitative and quantitively characterised using transmission electron microscopy, nanoparticle tracking analysis and western blotting. In addition, total RNA, including miRNA, was isolated, sequenced and identified from SP-EVs samples. Different SP-EVs concentrations (8.53 × 1011 ± 1.04 × 1011 and 1.84 × 1012 ± 1.75 × 1011 particles/mL of SP; P = 0.008), with a similar average size (143.9 ± 11.9 and 115.5 ± 2.4 nm; P = 0.7422) in F and S males, respectively was observed. Particle size was not significantly correlated with any kinetic parameter. The concentration of SP-EVs was positively correlated with the percentage of abnormal forms (r = 0.94; P < 0.05) and with the percentage of immotile spermatozoa (r = 0.88; P < 0.05). Small-RNA-seq analysis identified a total of 267 and 244 expressed miRNAs in the F and S groups, respectively. Two miRNAs (let-7b-5p and let-7a-5p) were the top most abundant miRNAs in both groups. Differential expression analysis revealed that 9 miRNAs including miR-190b-5p, miR-193b-5p, let-7b-3p, and miR-378-3p, and another 9 miRNAs including miR-7a-5p, miR-33a-5p, miR-449a-5p, and miR-146a-5p were significantly up- and downregulated in the F compared to the S group, respectively. The SP from F and S rabbit males contains EVs with different miRNA cargo correlated with spermatogenesis, homeostasis, and infertility, which could be used as biomarkers for male fertility and potential therapies for assisted reproductive technologies.

Female reproduction and the microbiota in mammals: Where are we?

While it is generally accepted that the mammalian vagina contains a site-specific microbiota that plays relevant roles in genital and reproductive health, the existence of an extra-vaginal microbiota in the female reproductive tract (i.e. follicular fluid, oviduct, endometrium, and placenta) is, at least, a matter of controversy. Many conclusions in this field have failed to consider the technical limitations, biases, and confounding factors inherent to next-generation sequencing (NGS) approaches. While this creates uncertainty in the field, there is no doubt this subject is set to be the focus of new research efforts because of its scientific and practical connotations in female reproductive health. The current art state, its limitations, and gaps in our knowledge about the female reproductive tract's microbiota and, particularly, about the microbes of the extra-vaginal environment are presented in this review. Also are discussed possible relationships between the gut and oral microbiota and reproductive events.

Influence of Different Regimes of Moderate Maternal Feed Restriction during Pregnancy of Primiparous Rabbit Does on Long-Term Metabolic Energy Homeostasis, Productive Performance and Welfare.

In this study, a maternal feed restriction (MFR; 105 g/d) in primiparous rabbit does was applied from day 0 to 7 post artificial insemination (AI) (R07, n = 96), from day 7 to 21 post AI (R721, n = 92), from day 0 to 21 post AI (R021, n = 94) or fed ad libitum during whole pregnancy (Control, n= 92). Feed intake (FI) was measured after MFR was over. On day 28 of gestation, fetoplacental development was evaluated (n = 11/group) and the productive parameters of the remaining dams were analyzed. Plasma free tri-iodothyronine (T3) and thyroxine, glucose, insulin, non-esterified fatty acids (NEFA), and corticosterone were analyzed during gestation and lactation (n = 5/group). After MFR, all groups significantly increased their voluntary FI. The longer MFR was, the lower the weight and length of the fetuses, but no long-term effects over litter performance were observed. R021 groups had the lowest T3 and the highest NEFA concentrations during pregnancy and showed insulin resistance at the end of gestation, but during lactation, energy homeostasis was balanced in all groups. MFR did not affect corticosterone concentrations. In conclusion, the ration setting applied slightly involved the energy homeostasis and metabolism of the animals, but their overall metabolic condition, productive performance and welfare were not compromised.

Gestation Food Restriction and Refeeding Compensate Maternal Energy Status and Alleviate Metabolic Consequences in Juvenile Offspring in a Rabbit Model.

Nutritional status during gestation can influence mother and offspring metabolism. Undernutrition in pregnancy affects women in both western and developing countries, and it is associated with a high prevalence of chronic diseases in later life. The present work was conducted in the rabbit model, as a longitudinal study, to examine the effect of food restriction during early and mid-gestation, and re-feeding ad libitum until the end of pregnancy on metabolic status and body reserves of mother and, its association with development and metabolism of fetuses and female offspring to the juvenile stage. Little changes in live body weight (LBW), compensatory feed intake, similar body reserves, and metabolism were observed in dams. Placenta biometry and efficiency were slightly affected, but fetal BW and phenotype were not modified. However, hyperinsulinemia, insulin resistance, and hypertriglyceridemia were demonstrated in pre-term fetuses. In the juvenile period, these changes were not evidenced, and a similar pattern of growth and serum metabolic parameters in offspring of food-restricted mothers were found, except in serum aminotransferases levels, which increased. These were associated with higher liver fibrosis. Maternal food restriction in the early and mid-pregnancy followed by re-feeding in our rabbit model established a compensatory energy status in dams and alleviated potential long-term consequences in growth and metabolism in the offspring, even if fetal metabolism was altered.

Physiological effects on rabbit sperm and reproductive response to recombinant rabbit beta nerve growth factor administered by intravaginal route in rabbit does.

Beta nerve growth factor (ß-NGF) is present in the seminal plasma of some species, including rabbits, acting as an ovulation-inducing factor in camelids. Traditionally, GnRH analogues are used to induce ovulation by intramuscular route when artificial insemination (AI) is performed in rabbit does. A specific rabbit recombinant ß-NGF (rrß-NGF) produced in our laboratory was tested as an alternative method to conventional treatment with GnRH analogues to induce ovulation. In the present work, different concentrations (0, 20, 100 ng/mL and 1, 20 and 100 µg/mL) of rrß-NGF were added to diluted semen to assess its effect on sperm traits (viability and motility parameters). rrß-NG was used also, incorporated to the AI dose, to evaluate ovulation response (LH and progesterone plasma concentrations, ovulation rate (OR) and embryo implantation at Day 7) after intravaginal administration. A negative control group stimulated with an empty catheter, and a positive control group inseminated and intramuscularly treated as usual with GnRH were also set up. Results showed that seminal quality was influenced by rrß-NGF depending on the concentration added, being the highest concentrations tested deleterious for semen. Whereas the highest OR was found in the positive control group (100%), concentrations of 20 ng/mL, 1 µg/mL and 20 µg/mL of rrß-NGF triggered intermediate OR (30, 60 and 42.9%, respectively), and 100 ng/mL and 100 µg/mL had the lowest OR (20 and 14.3%, respectively). Although LH peak was not observed in the first 2 h after AI in the ovulated females from rrß-NGF groups, plasma progesterone significantly increased at Day 7, except in those females treated with 20 and 100 µg/mL. Also, 98.4% of ovulated females were pregnant on Day 7. In conclusion, rrß-NGF added to diluted semen affects seminal quality and provokes ovulation, the development of functional CL and conception by intravaginal route in rabbit does, depending on the concentration added.

Correction: Recombinant rabbit beta nerve growth factor production and its biological effects on sperm and ovulation in rabbits.

[This corrects the article DOI: 10.1371/journal.pone.0219780.].

Supplementation with Fish Oil Improves Meat Fatty Acid Profile although Impairs Growth Performance of Early Weaned Rabbits.

Our objective was to analyze the influence of replacing lard (control) with fish oil (FO) rich in long-chain n-3 polyunsaturated fatty acids in the diet of rabbits weaned at 25 days of age on their growth performance, meat quality, cecal fermentation, and ileal morphology. Twenty-four litters (12 control and 12 FO) of nine kits each were fed the experimental diets from weaning (25 days) until slaughter at 60 days of age. Half of the litters (six per diet) were used to monitor productive performance, carcass characteristics, and ileal morphology, and cecal fermentation was assessed in the rest of litters. Diet had no influence on feed intake, meat color, and pH or cecal fermentation, but FO-fed rabbits had lower (p ≤ 0.049) average daily gain, chilled carcass weight, and perirenal fat than control rabbits. Fish oil inclusion in the diet resulted in lower morbidity (5.56% vs. 20.4%; p = 0.019) and a healthier fatty acid profile with lower (p < 0.001) n-6/n-3 ratios in both muscle and perirenal fat. In summary, the inclusion of FO in the diet of early weaned rabbits improved the fatty acid profile of rabbit meat and fat and decreased the morbidity, but growth performance was slightly reduced.

Recombinant rabbit beta nerve growth factor production and its biological effects on sperm and ovulation in rabbits.

In some induced-ovulating species, beta nerve growth factor (ß-NGF) has important roles in ovulation, though data for rabbits are still inconclusive. In this study we first synthesized functional recombinant ß-NGF from rabbit tissue (rrß-NGF) to address the following objectives: 1) to compare rabbit ß-NGF amino acid sequence with those of other induced- or spontaneous-ovulating species; 2) to assess the effects of rrß-NGF on rabbit sperm viability and motility, and 3) to examine the in vivo ovulation inducing effect of rrß-NGF added to the seminal dose in rabbit does. The NGF gene in rabbit prostate tissue was sequenced by Rapid Amplification of cDNA Ends and annotated in GenBank (KX528686). Recombinant rß-NGF was produced in CHO cells and purified by affinity chromatography. Once confirmed by Western blotting and mass spectrometry (MALDI-TOF) that the amino acid sequence of the recombinant protein corresponded to ß-NGF, its functionality was validated in PC12 cells in a successful dose-response study over 8 days. The amino acid sequence of prostate rabbit NGF differed to that of other species mainly in its receptor binding sites. In all the spontaneous ovulating species examined, compared with rabbit, alanine and proline residues, which interact with the high-affinity receptor, were replaced by a serine. In rabbits, asparagine and methionine were substituted by lysine at the low-affinity receptor binding site. In time- and dose-response experiments, the in vitro addition of rrß-NGF to the ejaculate did not affect sperm viability whereas sperm motility parameters were enhanced by the addition of 1 µg/mL of the neuropeptide. Addition of this same concentration of rrß-NGF to the seminal dose administered via the intravaginal route in does induced ovulation with a delayed LH peak, leading to a plasma progesterone increase, gestation and delivery. Our findings suggest that rrß-NGF could be a useful option for biotechnological and reproduction assisted techniques in rabbits but further studies are needed.

Characterization of ß-Nerve Growth Factor-TrkA system in male reproductive tract of rabbit and the relationship between ß-NGF and testosterone levels with seminal quality during sexual maturation.

ß-Nerve Growth Factor (ß-NGF) is a neurotrophin which acts through its receptors TrkA and p75, performing important actions in male reproductive physiology and its presence in seminal plasma (SP) has been related to male fertility. The aim of the present study was to evaluate the gene expression profile and the immunolocalization of ß-NGF and its high-affinity receptor TrkA in sex organs in rabbits during sexual maturation period. ß-NGF concentration for both SP and blood plasma (BP) and BP testosterone levels were determined as well as the seminal parameters during such period. Ten New Zealand White x California young rabbits were trained to semen collection since 20 weeks of age and routinely done once a week with two ejaculations per session. At 22 and 37 weeks of age, semen collection was carried out three times a week and seminal parameters were evaluated. Four males were randomly assigned and slaughtered in each age (n = 8); sex organs (prostate, bulbourethral glands and epididymis) were dissected and collected to determine ß-NGF and TrkA gene expression and immunolocalization. SP and BP were also taken at each semen collection session to evaluate ß-NGF concentration, and testosterone levels were also assessed in BP. The highest ß-NGF mRNA expression was observed in prostate compared to bulbourethral glands and epididymis. These two last tissues showed residual ß-NGF mRNA expression and limited localization of the neurotrophin. The prostate epithelial cells and lumen were strongly stained with regard to the other sex organs indicating that immunolocalization of ß-NGF rely mainly in the prostate. TrkA gene expression was lower but constant and differentially immunolocalized in the sex organ tissues. Finally, ß-NGF concentration in SP and BP remained unchanged in accordance to age, while some seminal characteristics such as sperm concentration, percentage of live sperm and mass and progressive motility were enhanced as endowed by BP testosterone variation. ß-NGF and its cognate TrkA receptor are expressed and immunolocalized in the male reproductive tract in the two ages studied, independently of the circulating levels of testosterone and ß-NGF.

Gene expression and immunolocalization of low-affinity neurotrophin receptor (p75) in rabbit male reproductive tract during sexual maturation.

This study reports the gene expression and immunolocalization of the low-affinity neurotrophin receptor, p75, in accessory glands (prostate and bulbourethral glands) and epididymis (caput and cauda) of male rabbits during sexual maturation. We showed that p75 was expressed in all tissues studied with similar mRNA levels during this period. However, it was differentially immunolocalized in bulbourethral glands and stereocilia of epididymis. These findings may be related with some remodeling processes in the accessory glands during sexual maturation, which could be associated with sperm maturation. The interaction of p75 with neurotrophins in rabbit male reproductive tract suggests the possible implication of this system in sexual maturation in rabbits.

The effects of sildenafil citrate on feto-placental development and haemodynamics in a rabbit model of intrauterine growth restriction.

The present study evaluated the effectiveness of sildenafil citrate (SC) to improve placental and fetal growth in a diet-induced rabbit model of intrauterine growth restriction (IUGR). Pregnant rabbits were fed either ad libitum (Group C) or restricted to 50% of dietary requirements (Group R) or restricted and treated with SC (Group SC). The treatment with SC improved placental development by increasing vascularity and vessel hypertrophy in the decidua. The assessment of feto-placental haemodynamics showed higher resistance and pulsatility indices at the middle cerebral artery (MCA) in fetuses treated with SC when compared with Group R, which had increased systolic peak and time-averaged mean velocities at the MCA. Furthermore, fetuses in the SC group had significantly higher biparietal and thoracic diameters and longer crown-rump lengths than fetuses in Group R. Hence, the SC group had a reduced IUGR rate and a higher kit size at birth compared with Group R. In conclusion, SC may provide potential benefits in pregnancies with placental insufficiency and IUGR, partially counteracting the negative effects of food restriction on placental development and fetal growth. However, the present study also found evidence of a possible blood overflow in the brain that warrants further investigation.