The effect of semen extender, seminal plasma and raw semen on uterine and ovarian blood flow in mares

Effects of natural mating, artificial insemination and intravaginal deposition of raw semen or seminal plasma on vaginal and uterine blood flow in German Holstein cows

AIM

The present study was performed to characterize and compare the perfusion of vaginal and uterine arteries after challenging the reproductive tract of dairy cows via natural mating, artificial insemination (AI), or intravaginal deposition (vaginal fundus) of different biological fluids or a placebo.

MATERIALS AND METHODS

In a double-blind study, six German Holstein cows were administered PGF2α during dioestrus and 48 h later treated with GnRH. Intravaginal or intrauterine treatments were carried out 12 h after GnRH was administered. Animals served as their controls, using a cross-over design with an interval of 14 days between experiments. The experimental animals were allocated to receive the following treatments: natural mating (N), intrauterine artificial insemination (A), intravaginal deposition (vaginal fundus) of 6 mL raw semen (R) or 6 mL seminal plasma (S), and compared to their controls [control 1: 6 mL placebo (P: physiological saline); control 2: no treatment (C)). Corresponding time intervals were chosen for the untreated control oestrus. Blood flow volume (BFV) in the uterine (u) and vaginal (v) arteries ipsilateral to the ovary bearing the preovulatory follicle was determined using transrectal Doppler sonography.

RESULTS

All animals exhibited oestrus and ovulated between 30 and 36 h after GnRH. Transient increases (P < 0.05) in vaginal blood flow occurred between 3 and 12 h following mating as well as 3 to 9 h after deposition of raw semen and seminal plasma, respectively. The most distinct increases (199%) in vBFV occurred 6 h after mating compared to values immediately before mating (= time 0 h). Neither AI nor deposition of a placebo into the vagina affected vBFV (P > 0.05). Only mating and deposition of either raw semen, seminal plasma or AI increased uBFV (P < 0.003). The greatest rise in uBFV occurred after natural mating. Maximum uBFV values were detected 9 h after mating when values were 79% greater (P < 0.05) than at 0 h.

CONCLUSIONS

The natural mating, deposition of raw semen or seminal plasma and conventional AI affect vaginal and/or uterine blood flow to different degrees. The factors responsible for these alterations in blood flow and their effects on fertility remain to be clarified in future studies.

Investigation of the Effect of Seminal Plasma Exosomes from the Normal and Oligoasthenoteratospermic Males in the Implantation Process

Background

Seminal plasma exosomes are now recognized to play a complex role in the regulation of the female reproductive system infertility. The objective of this study was to assess the effect of exosomes derived from the sperm of men with oligoasthenoteratozoospermia on endometrial implantation-related genes.

Methods

To isolate the exosomes, we employed an ultracentrifugation method on samples derived from 10 fertile men with normal sperm parameters and 10 men with oligoasthenoteratozoospermia. The size distribution and ultrastructure of the exosomes were then characterized using transmission electron microscopy and dynamic light scattering. We detected an exosome marker using western blot analysis and confirmed the cytoplasmic localization of the exosomes by incubating them with DiI dye and visualizing them using fluorescence microscopy. After 6 hours of in vitro treatment of endometrial epithelial cells with 100 µg/ml seminal exosome, the endometrial receptivity genes were examined using qRT-PCR. To perform data analysis and quantification, we utilized Image J and Prism software. P< 0.05 were considered statistically significant.

Results

After 6 hours of treatment, the mRNA levels of MUC1, LIF, G-CSF, CX3CL1, and VEGF were significantly downregulated in the endometrial epithelial cells treated with oligoasthenoteratozoospermia exosomes compared to the normal group. Although changes were observed in the mean mRNA levels of IL8 and TGF-β genes in the oligoasthenoteratozoospermia group compared to the normal group, these differences did not reach statistical significance (p > 0.05).

Conclusions

Oligoasthenoteratozoospermia exosomes have a distinct effect on endometrial receptivity compared to normal exosomes, leading to reduced expression of implantation-related genes.

Effects of Intra-Uterine Fluid Accumulation after Artificial Insemination on Luteal Function in Mares

After breeding or artificial insemination, especially with frozen/thawed semen, mares often develop a persistent uterine inflammation, which is diagnosed by intra-uterine fluid accumulation. Here, we explored whether intra-uterine fluid accumulation affects corpus luteum function and tested the hypothesis that intra-uterine fluid accumulation after artificial insemination alters blood flow in the corpus luteum and plasma progesterone concentrations. A total of 40 Standardbred mares were artificially inseminated with frozen-thawed semen 30 to 36 h after induction of ovulation, and cases with or without intra-uterine fluid accumulation were detected by ultrasound 12 h after insemination. Luteal blood flow was measured by Power Doppler ultrasonography 3 and 6 days after ovulation, progesterone concentration was measured in peripheral plasma by ELISA 6 days after ovulation, and pregnancy was diagnosed by ultrasonography 14 days after ovulation. Luteal blood flow increased between 3 and 6 days after ovulation, but blood flow did not differ significantly between cases with (n = 28) and without (n = 25) intra-uterine fluid accumulation after insemination. Surprisingly, progesterone concentrations were higher in cases of intra-uterine fluid accumulation than cases without (9.3 ± 1.1 vs. 6.6 ± 0.5 ng/mL, p = 0.048). Pregnancy was less likely in cases with intra-uterine fluid accumulation than in cases without (10/28 vs. 17/25, p = 0.019), and there was a negative correlation between the severity of intra-uterine fluid accumulation and per cycle pregnancy rate. These data suggest that although intra-uterine fluid accumulation increases the secretion of progesterone, pregnancy is more dependent on uterine health than ovarian function.

Analysis of Uterine Blood Flow in Breeding Sows through the Estrus and Early Diestrus, and after Artificial Insemination

This study aimed to determine uterine blood flow indices by transabdominal Doppler ultrasound in sows (n = 18) under different conditions: (i) sows after estrus detection (day 0, D0); (ii) sows 2 h after artificial insemination (AI), performed 24 h after detection of estrus (day 1, D1); (iii) sows in early diestrus (day 5, D5). Moreover, three different types of seminal doses were used for AI depending on the ejaculate fraction included (F1: doses containing only the rich fraction of the ejaculate; F2: F1 + the transition fraction between rich and poor fractions; F3: F2 and poor fraction). The statistical analysis revealed significant differences in some indices regarding the period of analysis (D0, D1, and D5). Diastolic velocity and mean velocity showed lower values at D5 in comparison with D0 and D1 (p < 0.01). On the other hand, the pulsatility index and the relationship systolic velocity/diastolic velocity indicated higher values at D5 in comparison with D0 and D1 (p < 0.01). No differences were observed regarding the type of seminal dose used in any of the time points analyzed (p > 0.05). Neither insemination per se nor the type of ejaculate fraction used immediately modified the uterine vascularity, but some indices are affected by the stage of the estrus cycle (estrus vs. early diestrus).

Doppler Ultrasound in the Reproduction of Mares

Doppler ultrasonographic (US) is a method that provides real-time information on vascular architecture and hemodynamic aspects of blood vessels. It can determine the presence, direction, and speed of blood flow, being subdivided into the categories of color Doppler (color flow and power flow) and pulsed Doppler. The objective of this chapter was to compile data from several studies addressing the use of US Doppler correlated with pathophysiological phenomena of equine reproduction. Initially we decided to describe the technique, advantages, and disadvantages of each Doppler mode. Then the applicability of US Doppler in mares related to equine reproduction. Thus, within this chapter, you will find the form of use and descriptions of studies carried out on vascular perfusion of the follicular dynamics, the corpus luteum, the uterine segments, which we have divided into post-insemination evaluation, endometritis diagnosis and pregnancy diagnosis. So, we hope that this chapter will expand the knowledge about US Doppler and increase the number of veterinarians who will introduce the technique into their practical routine.

Oxidative profile and protease regulator potential to predict sperm functionality in donkey (Equus asinus)

Seminal plasma (SP) of donkey stallions was evaluated using various oxidative stress parameters as well as protease and protease inhibitor activities. SP was obtained by nine donkey stallions. In addition, one donkey stallion with non-obstructive azoospermia was enrolled in this study. Free radical scavenging activity (FRSA), the ferric reducing ability of plasma (FRAP), total antioxidant capacity (TAC), and total thiol level (TTL) were highly correlated with each other and with the protease inhibitor activity. However, only FRAP, TAC, and the nitrate/nitrite concentration (NOx) were significantly correlated with sperm concentration, production, and kinetics. Protease inhibitor activity was highly correlated with sperm concentration and production; however, it did not correlate with sperm kinetics. The azoospermic stallion produced a lower amount of semen than the normospermic stallions and its SP showed a lower antioxidant activity when evaluated with FRAP, TAC, and TTL as well as a higher NOx and a lower protease inhibitor activity. In conclusion, the evaluation of SP oxidative profile by FRAP, TAC, and NOx may provide reliable information on donkey sperm quality whereas protease inhibitor activity may play a role as a marker of the sperm concentration in this species.

Endometrial angiogenesis induced by uterine insufflation with an oxygen-ozone gas mixture in mares

Ozone (O₃ ) therapy has been used to improve peripheral tissue oxygenation in humans and domestic animals. The goal of the present study was to characterize histological changes in the endometria of healthy equines following tissue exposure to gas mixtures enriched with different concentrations of O₃ . Cycling mares without endometrial degeneration were divided into three groups according to treatment (n = 9 mares/group). The uteri from the O₃ , ½O₃ and control groups were insufflated for 3 min with gas containing 42, 21 and 0 μg O₃ ml^-1 , respectively. Treatments were performed every three days from D0 to D6. Endometrial samples were collected immediately before the first treatment and 24 hr after the last treatment. The following nine histological parameters were evaluated: (i) the number of endometrial blood vessels, (ii) endometrial vascular degree (EVD), (iii) increase rate of blood vessels, (iv) increase rate of EVD, (v) glandular total area, (vi) glandular lumen area, (vii) intraglandular secretion area, (viii) glandular epithelial height and (ix) luminal epithelial height. In the O₃ group, a positive effect from treatment (p < .01) was detected for all vascular parameters (i, ii, iii and iv), glandular total area, intraglandular secretion area and glandular epithelial height. Compared to the control group, the ½O₃ group had greater (p < .01) EVD (84.1 ± 12%) and a higher increase rate of blood vessels (151.9 ± 47.1%). Uterine insufflation with low or intermediate concentrations of the O₂ -O₃ gas mixture induced endometrial angiogenesis. Morphometry, but not morphology, of the endometrial glands was affected by local O₃ therapy. These findings would be of great significance for the development of new therapies for infertility in mares.

Intrauterine infusion of killed semen adversely affects uterine blood flow and endometrial gene expression of inflammatory cytokines in mares susceptible to persistent breeding-induced endometritis

Persistent breeding-induced endometritis (PBIE) is a leading cause of infertility in mares. The objective of the study was to assess genital perfusion and endometrial gene expression of inflammatory cytokines in mares classified as susceptible (n = 5) or resistant (n = 5) to PBIE. Ten mares were examined daily during estrus until 6 d after hCG-induced ovulation for two estrous cycles. Twenty-four hours after application of 1500 IU hCG, 4 mL of killed (by repeated freezing in liquid nitrogen and thawing at 50 °C) deep-frozen semen or sterile saline was instilled into the uterine body and examinations were carried out immediately before and 3, 6, and 12 h after intrauterine infusion. Examinations included blood sampling to determine plasma progesterone (P₄) concentrations, and transrectal ultrasonography in B- and color Doppler mode to determine follicular and luteal size and blood flow, the extent of intrauterine fluid, as well as time-averaged maximum velocity (TAMV), blood flow volume (BFV), and blood flow resistance (expressed as pulsatility index, PI) of the uterine arteries. Additionally, endometrial biopsies were obtained at 24 h before, and 2 and 7 d after infusion, and mRNA expressions of IL1B, IL6, IL8, IL10, TNF, CASP3, and COX2 were determined by qRT-PCR. Statistical analyses were performed with mixed models. Intrauterine fluid retention (diameter >20 mm for at least 3 d) was found after infusion of killed semen in five susceptible mares. There was no treatment effect (semen vs saline; P > 0.05) on genital blood flow, plasma P₄ concentration, and endometrial gene expression. In comparison to resistant mares, susceptible mares had an increased (P = 0.04) BFV of the uterine arteries at 24 h before intrauterine infusion of killed semen, and an increased (P = 0.03) PI at 2 d after infusion. The TAMV, plasma P₄ concentrations, and follicular and luteal size and blood flow did not differ (P > 0.05) between resistant and susceptible mares. Endometrial mRNA expression of IL1B increased (P = 0.05) at 2 d after the infusion of killed semen in the susceptible mares, and the expression of IL10 increased (P = 0.003) at 7 d after the infusion within the resistant mares. Interleukin 6 mRNA was increased (P = 0.05) in susceptible compared to resistant mares at 2 d after infusion. In summary, an intrauterine infusion of killed semen increases uterine blood flow resistance and alters endometrial gene expression of inflammatory cytokines for at least 7 d but does not affect ovarian blood supply and luteal function in mares susceptible to PBIE.

Uterine hemodynamic patterns, oxidative stress, and chromoendoscopy in mares with endometritis

This study aimed to evaluate the use of Doppler ultrasound for determining alterations in uterine thickness and uterine arteries, use of chromohysteroscopy in evaluating endometritis with biopsies, and the impact of endometritis on oxidative and hormonal status. Twenty Arabian mares were divided into control and endometritis groups. Each underwent a physical examination, Doppler ultrasound, chromoendoscopy, and uterine biopsy. Blood samples from each animal were collected for hematologic, hormonal, and oxidative analysis. Results revealed a significant increase in estradiol, malondialdehyde (MDA), and nitric oxide metabolites (NOMs) associated with a significant decrease in progesterone and total antioxidant capacity (TAC) in the endometritis group. There was a significant difference in uterine thickness in the endometritis group. Uterine blood flow analyzed by color mode showed a significant increase in the endometritis group, while the spectral mode showed a significant increase in Doppler velocities and blood flow rate accompanied by a significant decrease in Doppler indices. The endometritis group showed ridged, bluish color in the endometrial wall, indicating hyperemia. Biopsy showed mononuclear inflammatory cells and edema in the endometrial interstitial tissue with sloughing of the epithelial lining. Conclusion: Endometritis in mares is associated with oxidative processes and presents with an increase in MDA and NOMs and a decrease in TAC. Doppler ultrasound improved endometritis diagnosis because it showed alterations in uterine vascularization. Chromoendoscopy improved the accuracy in taking biopsy samples because it allows the practitioner to select appropriate areas for biopsy to improve histopathological diagnostic outcomes. Therefore, this technique is worthy of further study in the field of veterinary equine reproduction.

The Female Response to Seminal Fluid

Seminal fluid is often assumed to have just one function in mammalian reproduction, delivering sperm to fertilize oocytes. But seminal fluid also transmits signaling agents that interact with female reproductive tissues to facilitate conception and .pregnancy. Upon seminal fluid contact, female tissues initiate a controlled inflammatory response that affects several aspects of reproductive function to ultimately maximize the chances of a male producing healthy offspring. This effect is best characterized in mice, where the female response involves several steps. Initially, seminal fluid factors cause leukocytes to infiltrate the female reproductive tract, and to selectively target and eliminate excess sperm. Other signals stimulate ovulation, induce an altered transcriptional program in female tract tissues that modulates embryo developmental programming, and initiate immune adaptations to promote receptivity to implantation and placental development. A key result is expansion of the pool of regulatory T cells that assist implantation by suppressing inflammation, mediating tolerance to male transplantation antigens, and promoting uterine vascular adaptation and placental development. Principal signaling agents in seminal fluid include prostaglandins and transforming growth factor-β. The balance of male signals affects the nature of the female response, providing a mechanism of ‟cryptic female choiceˮ that influences female reproductive investment. Male-female seminal fluid signaling is evident in all mammalian species investigated including human, and effects of seminal fluid in invertebrates indicate evolutionarily conserved mechanisms. Understanding the female response to seminal fluid will shed new light on infertility and pregnancy disorders and is critical to defining how events at conception influence offspring health.

Effects of pentoxifylline supplementation to semen extender on post-breeding inflammation response assessed by endometrial cytology and vascular perfusion in mares

The aim was to evaluate effects of addition of pentoxifylline to skimmed milk semen extender on uterine inflammatory response. Thirty-six estrous cycles of 15 mares were randomly divided into five groups for artificial insemination (AI): Control: mimicking the AI procedure (n = 7); Extender: deposition of skimmed milk based extender (n = 7); Extender + PTX: skimmed milk based extender plus pentoxifylline (7.18 mM; n = 8); Semen: semen diluted with extender without pentoxifylline (n = 7), and Semen + PTX: semen diluted with extender containing pentoxifylline (n = 7). Mares in estrus were examined by trans-rectal palpation and using ultrasonography, and ovulation was induced. Uterine hemodynamics were assessed immediately before ovulation induction (T-30), immediately before AI (T0), 2 (T2), 6 (T6), 12 (T12), 24 (T24) and 48 (T48) h after AI. Endometrial samples were collected 6 h after AI, and slides were stained and examined to determine percentage of PMN. Pentoxifylline had no additional effect on vascular perfusion. There was a major inflammatory response with pentoxifylline treatment that was greater than that of the control group. In the group treated with Extender + PTX, there were more PMN (57.98 ± 9.42%) than in the group treated with Extender (20.20 ± 6.63%) and in the Semen + PTX group more PMN (82.84 ± 5.71%) than in the Semen-treated group (47.83 ± 10.61%). These findings indicate the addition of pentoxifylline does not stimulate blood flow; however, it induces a greater immune defense response because more neutrophils migrate to the uterine lumen.

Evaluation of the effect of mating, intrauterine deposition of raw seminal plasma or seminal plasma purified β-NGF on endometrial vascularization in llamas

The aim of this study was to evaluate the endometrial vascularization area (EVA) of both uterine horns in llamas subjected to different intrauterine treatments resembling physiological conditions after a single mating. Llamas with a growing follicle (≥8 mm) were randomly assigned to: a) single mating with a fertile male (mating; positive control; n = 6); b) intramuscular administration of 50 μg of gonadorelin acetate plus an intrauterine infusion of 4 ml of PBS (GnRH; negative control; n = 4); c) intrauterine infusion of 4 ml of raw llama seminal plasma (SP; n = 4) or d) intrauterine infusion of 10 mg of β-NGF purified from llama semen diluted in 4 ml of PBS (spβ-NGF; n = 6). Females in GnRH, SP and NGF group received 50% of treatment volume into each horn by guiding an insemination pipet through the cervix. Ovaries were examined by ultrasonography every 12 h until Day2 (Day 0 = Day of treatment) to determine ovulation. Power-Doppler ultrasonography evaluation of EVA in a cross-section of the middle segment of each horn was conducted at 1 h before and 1, 3, 6, 12 and 24 h (intensive evaluation) and 2, 4, 6 and 8 days (long-term evaluation) after treatment administration. Serial EVA data was analyzed as a 2-by-2 factorial design for repeated measures using the MIXED procedure. The analysis included main effects of treatment (mating, SP, spβ-NGF or GnRH), uterine horn (left vs right), time, and their interactions. According to the 2 by 2 analysis there was no effect of uterine horn on EVA during the first 24 h and from Day 2 to Day 8 after treatment; therefore, data were grouped based on treatment type regardless of uterine horn for both periods of observation. Thus, EVA was affected by time (P < 0.04) and treatment by time interaction (P < 0.02) and tended (P = 0.07) to be influenced by type of treatment during the intensive evaluation period. Females on mating and spβ-NGF group showed a significant increase in EVA at 3 and 12 h after treatment compared to GnRH and SP groups. However, no effect of treatment, time or their interaction was observed during the long-term evaluation period. In spite of the limited number of animals used in this study, our results allow us to concluded that natural mating and intrauterine deposition of 10 mg of spβ-NGF induce a symmetrical increase in endometrial vascularization of both uterine horns during the first 24 h post treatment administration in llamas; however, this effect did not persist beyond that period.

Effects of induced endometritis on uterine blood flow in cows as evaluated by transrectal Doppler sonography

This study was conducted to evaluate the effects of induced endometritis on uterine blood flow in cows. Transrectal Doppler sonography was performed on uterine arteries of six cyclic cows before and for 4 days after inducing acute endometritis by intrauterine infusion of 720 mg of policresulen, and for 4 days of the following estrous cycle. Time-averaged maximum velocity (TAMV) increased (p < 0.001) and pulsatility index (PI) decreased (p < 0.0001) within 1 h of policresulen administration, and did not change (p > 0.05) in the next 4 days of the same cycle. TAMV and PI values in the subsequent cycle did not differ (p > 0.05) from the values measured before infusion and showed no changes (p > 0.05) within the cycle. Blood flow parameters were not related (p > 0.05) to plasma concentrations of progesterone and estrogen. All cows showed an acute endometritis determined by histopathological findings of biopsy samples taken 1 day after infusion and fibrotic endometrial alterations detected in the subsequent cycle. No relationships were observed between fibrotic changes of the endometrium and uterine blood flow during either cycle. In conclusion, acute inflammation is accompanied by a rise in uterine blood flow, but fibrotic alterations do not seem to be related to Doppler sonographic findings.

Seminal Fluid Signalling in the Female Reproductive Tract: Implications for Reproductive Success and Offspring Health

Carriage of sperm is not the only function of seminal fluid in mammals. Studies in mice show that at conception, seminal fluid interacts with the female reproductive tract to induce responses which influence whether or not pregnancy will occur, and to set in train effects that help shape subsequent fetal development. In particular, seminal fluid initiates female immune adaptation processes required to tolerate male transplantation antigens present in seminal fluid and inherited by the conceptus. A tolerogenic immune environment to facilitate pregnancy depends on regulatory T cells (Treg cells), which recognise male antigens and function to suppress inflammation and immune rejection responses. The female response to seminal fluid stimulates the generation of Treg cells that protect the conceptus from inflammatory damage, to support implantation and placental development. Seminal fluid also elicits molecular and cellular changes in the oviduct and endometrium that directly promote embryo development and implantation competence. The plasma fraction of seminal fluid plays a key role in this process with soluble factors, including TGFB, prostaglandin-E, and TLR4 ligands, demonstrated to contribute to the peri-conception immune environment. Recent studies show that conception in the absence of seminal plasma in mice impairs embryo development and alters fetal development to impact the phenotype of offspring, with adverse effects on adult metabolic function particularly in males. This review summarises our current understanding of the molecular responses to seminal fluid and how this contributes to the establishment of pregnancy, generation of an immune-regulatory environment and programming long-term offspring health.

Donkey jack (Equus asinus) semen cryopreservation: studies of seminal parameters, post breeding inflammatory response, and fertility in donkey jennies

The aims of this study were (1) to evaluate motility parameters of donkey jack (jack; Equus asinus) semen cryopreserved in INRA-96 (INRA; IMV Technologies, France, 2% egg-yolk enriched) using either glycerol (GLY) or ethylene glycol (EG) as a cryoprotector; (2) to compare in vitro the postthaw re-extension with homologous seminal plasma (SPL) or INRA; (3) to compare fertility in donkey jennies (jennies; Equus asinus) timed artificially inseminated with jack semen cryopreserved using GLY or EG, re-extended with INRA; (4) to compare fertility in jennies timed artificially inseminated with jack semen cryopreserved using GLY re-extended with SPL, INRA, or not re-extended (NN); and (5) to describe some preliminary results of the inflammatory uterine response postbreeding. Semen from two jacks was collected and frozen in an INRA-2% egg yolk extender added of either 2.2% GLY or 1.4% EG. Postthaw motility was evaluated by a computer-assisted motility analyzer. Uterine inflammatory response and fertility were evaluated after artificial insemination (AI) of 13 jennies with frozen-thawed semen, either further extended with INRA (Group GLY-INRA, 13 cycles, and EG-INRA, 8 cycles), or with SPL (Group GLY-SPL, 13 cycles), or not re-extended (GLY-NN, 5 cycles). In each cycle, jennies were bred twice with 500 × 10(6) sperm cells (250 × 10(6) from each jack), at fixed times after induction of ovulation, and uterus was flushed at 6 and 10 h after first and second breeding, respectively. Cells in the recovered fluid were counted and distinguished as polymorphonuclear neutrophils (PMN) or other cell types. Total and progressive motility did not differ between cryoprotectants, but were higher when semen samples were re-extended in INRA, compared with SPL (P < 0.05). Pregnancy was diagnosed by transrectal palpation and ultrasonography examinations at 14 and 16 days postovulation. In 7/13 (53.8%) jennies and 12/39 (30.4%) cycles postbreeding intrauterine fluid accumulation was observed, with no differences between treatments (P < 0.05). Polymorphonuclear neutrophil numbers and concentrations were higher in the first flushing compared with the second, and PMN concentration was higher in GLY-SPL than in GLY-INRA (P < 0.05). Pregnancy rates in GLY-SPL, GLY-INRA, EG-INRA, and GLY-NN were 8/13, 3/13, 2/8, and 1/5, respectively. There was no significant difference either between the two cryoprotectants re-extended in INRA, or between re-extension groups. There was however a trend for GLY-SPL to improve pregnancy rates compared with GLY-INRA (P = 0.055). These results indicate that it is possible to obtain similar postthaw sperm motility and pregnancy rates using GLY or EG as a cryoprotectant for donkey semen, and that in the conditions of this study the re-extension in SPL of thawed semen before AI showed a trend toward the improvement of fertility and increased PMN concentration in uterine flushings.

Effect of seminal plasma on uterine inflammation, contractility and pregnancy rates in mares

REASONS FOR PERFORMING STUDY

There is conflicting evidence over the role seminal plasma plays in sperm transport and inflammation within the uterus of mares. In in vitro studies, seminal plasma has been shown to reduce polymorphonuclear neutrophil (PMN) function, but the opposite effect on uterine inflammation has been reported in vivo.

OBJECTIVES

To study the effect of seminal plasma on uterine contractility, inflammation and pregnancy rates by inseminating mares with low doses of sperm free from seminal plasma (Group 1) and containing seminal plasma (Group 2).

METHODS

Synchronised mares were inseminated with 50 x 10(6) sperm in either skim milk extender or seminal plasma. Uterine lavage was performed 6 h after insemination to assess the inflammatory response. The contraction frequency of the uterus was measured over a 4 min period 10 mins and 6 h after insemination, using B-mode ultrasonography. Pregnancy rates were assessed 16 days after insemination.

RESULTS

Uterine contractions were less frequent in Group 1 mares inseminated with seminal plasma and significantly more PMNs were found in the lavage fluid of those mares. Pregnancy rates were identical in both groups (62%).

CONCLUSIONS

This study provides evidence that seminal plasma decreases uterine contractility and increases the inflammatory response of the uterus to semen. No effect of seminal plasma on pregnancy rates was demonstrated.

POTENTIAL RELEVANCE

Mares that develop persistent mating-induced endometritis may have inherently poor uterine contractility and impaired uterine clearance. The presence of seminal plasma during breeding may not be desirable in these mares. The role of seminal plasma in problem mares warrants additional study.

Endometrial explant culture to study the response of equine endometrium to insemination

Mating-induced endometritis (MIE) is ubiquitous in the horse after natural mating and artificial insemination with frozen/thawed semen causing the most aggressive response. The majority of mares eliminate MIE 24-48 h after insemination. An endometrial explant culture was tested as a potential in vitro exemplar for sperm-induced MIE. Endometrial prostaglandin F(2alpha) (PGF(2alpha)) secretion and expression of interleukin-8 (IL-8) were used as markers of inflammation. Endometrial explants were cultured from uteri collected from follicular phase mares. Explants were challenged with 1 or 10 x 10(6) sperm/ml frozen/thawed semen, chilled semen, washed sperm or seminal plasma. Medium was collected 24 and 72 h after challenge and assayed for PGF(2alpha) by radioimmunoassay. Treatment of endometrial explants with frozen/thawed, chilled semen or washed sperm did not change the secretion of PGF(2alpha) compared with untreated controls. However, 24 h after challenge cultured explants expressed IL-8. The in vitro endometrial explant system did not represent the in vivo response to semen when PGF(2alpha) was used as a marker of inflammation, yet the use of gene expression as an inflammatory marker warrants further investigation.

Effect of sperm numbers and concentration on sperm transport and uterine inflammatory response in the mare

Our objective was to determine whether the concentration of cooled sperm inseminated influenced sperm transport and intensity of the uterine inflammatory reaction 2, 4 and 24h after insemination. Experimental subjects were 189 estrous mares with a dominant follicle > or =35 mm in diameter and no bacterial growth or neutrophils detected in uterine smears. Each mare was randomly assigned to receive one of the following intrauterine treatments (volume, 20 mL): insemination with 5x10(6) mL(-1) or 25x10(6) mL(-1) or 50x10(6) mL(-1) sperm diluted in 3 mL seminal plasma (SP) and 17 mL skim milk; seminal plasma or skim milk extender. Mares in a control group received no intrauterine treatment. Mares were slaughtered 2, 4 or 24h after insemination or infusion. Oviducts were separated from the uterus, and uterus and oviducts were then flushed with phosphate-buffered saline (PBS). After flushing, an endometrial sample was collected for further histopathological examination. The grade of uterine fibrosis and the amount of neutrophils in the stratum compactum were evaluated. A sample of each tubal flushing was examined for sperm count, and a sample of each uterine flushing was examined for PMN count. It was concluded that compounds in the insemination dose provoked a uterine inflammatory response, which was more rapid and intense as sperm concentration increased. In contrast, sperm transport through 4h after insemination was not influenced by sperm concentration.

Seminal plasma and male factor signalling in the female reproductive tract

In mammals, insemination results in the transmission of seminal factors that act, in the female reproductive tract, to promote sperm survival, to "condition" the female immune response to tolerate the conceptus and to organise molecular and cellular changes in the endometrium to facilitate embryo development and implantation. These events are initiated when signalling agents, including transforming growth factor-beta and other cytokines and prostaglandins secreted by seminal vesicle and prostate glands, interact with epithelial cells in the cervix and uterus to activate cytokine synthesis and to induce cellular and molecular changes resembling a classical inflammatory cascade. The consequences are the recruitment and activation of macrophages, granulocytes and dendritic cells, which have immune-regulatory and tissue-remodelling roles that culminate in improved endometrial receptivity to the implanting embryo. Cytokines elicited by seminal activation have embryotrophic properties and also contribute directly to the optimal development of the early embryo. This review summarises our current understanding of the physiology of responses to seminal plasma in the female reproductive tract and considers the evolutionary significance of seminal plasma in influencing female tissues to promote the success of pregnancy.

Effect of the inseminate and the site of insemination on the uterus and pregnancy rates of mares

In this review, effects of the composition of the inseminate on uterine response and pregnancy rates in mares are discussed. The inseminate can differ for volume, sperm concentration, total sperm numbers, presence, absence, or proportion of seminal plasma, and extender composition. Semen can be used as fresh, cooled, or frozen. The site of semen deposition also plays a role; semen is deposited either into the uterine body (standard artificial insemination (AI)) or into the tip of the uterine horn ipsilateral to the preovulatory follicle (deep AI) using the hysterocopical or transrectally guided techniques. In addition to pregnancy rates, some uterine responses to the inseminate are considered including myometrial contractions, transport and elimination of sperm, and uterine inflammation, which is reflected as numbers of polymorphonuclear leukocytes, enzyme levels, and presence of intrauterine fluid. Reproductively normal and abnormal mares are compared.