Quality of seminal fluids varies with type of stimulus at ejaculation.

The theory of ejaculate economics was mainly built around different sperm competition scenarios but also predicts that investments into ejaculates depend on female fecundity. Previous tests of this prediction focused on invertebrates and lower vertebrate, and on species with high female reproductive potential. It remains unclear whether the prediction also holds for polygynous mammals with low female reproductive potential (due to low litter size and long inter-birth intervals). We used horses (Equus caballus) to experimentally test whether semen characteristics are adjusted to the oestrous cycle of the mare a stallion is exposed to during few moments before ejaculation. We analysed 122 weekly semen samples collected from 16 stallions during exposure to either an oestrous or a dioestrous mare. Semen volume and the rate of motile sperm were higher when stallions were exposed to an oestrous than to a diestrous mare, while total sperm counts and sperm velocity remained unchanged. Sperm collected after exposure to an oestrous mare also showed reduced oxidative degeneration of cell membranes over a period of 48 hours. We conclude that stallions invest more into their seminal fluids when the chance of fertilization is elevated, and that this adjustment of ejaculate quality can happen very quickly

No increase in pregnancy rate of mares after preovulatory deep uterine horn application of misoprostol.

A potential source of fertility loss in mares is oviductal dysfunction, potentially caused by masses or debris in the lumen, that may prevent either sperm from reaching the fertilization site or the embryo from reaching the uterus. Recently a novel therapeutic method leading to increased pregnancy results was described by infusing misoprostol, a synthetic prostaglandin E1, in the uterus of mares with unexplained fertility problems. In this study, we aimed, after examining the compatibility of misoprostol with semen, to evaluate the pregnancy rate after routine preovulatory deep uterine horn application of misoprostol in clinically normal oestrous mares, which were inseminated in the same cycle. In experiment 1, ejaculates of 10 stallions diluted with INRA 96™ were mixed with different concentrations of misoprostol (0.01 mg/mL, 0.001 mg/mL, 0.0001 mg/mL, and 0.00001 mg/mL) and total semen motility was evaluated immediately, 12, 24, 48, and 72 h later, and compared with a control sample (mixed with NaCl 0.9%). In experiments 2 and 3, 33 privately-owned clinically normal oestrous mares were each allocated to a treatment or control group. Ovulation was then induced with intramuscularly 2.25 mg deslorelin acetate. At the moment of ovulation induction (experiment 2) and 24 h earlier (experiment 3), 0.2 mg misoprostol diluted in 2 mL NaCl 0.9% were applied deep in the uterine horn (treatment groups) and pure 2 mL NaCl 0.9% in the mares of the control groups. Mares were then inseminated 24 h after deslorelin administration and prior to ovulation with commercial chilled-warmed or frozen-thawed semen, as well as immediately after ovulation detection (both types of semen) maximally 48 h after ovulation induction. In experiment 1, regardless of time and compared with the control groups, all solutions with different concentrations of misoprostol had a negative effect on total motility of semen, which was significant for the highest concentrations (0.01 mg/mL: 18.0% reduction, CI = 22-13%, p = < 0.01). We found no beneficial effect of preovulatory uterine treatment with misoprostol on pregnancy rate (OR = 0.45, CI = 0.15-1.31, p = 0.14): in experiment 2, 2/11 (18.2%) mares of the treatment group became pregnant vs. 12/22 (54.5%) mares in the control group (OR = 0.19, CI = 0.03-1.06, p = 0.07), in experiment 3, 5/14 (35.7%) mares in the treatment group vs. 7/19 (36.8%) mares in the control group (OR = 0.95, CI = 0.23-4.02, p = 0.95), respectively. In conclusion, pregnancy rate was not increased in reproductively normal mares with routine preovulatory deep uterine horn application of misoprostol

Embryo survival in the oviduct not significantly influenced by major histocompatibility complex social signaling in the horse.

The major histocompatibility complex (MHC) influences sexual selection in various vertebrates. Recently, MHC-linked social signaling was also shown to influence female fertility in horses (Equus caballus) diagnosed 17 days after fertilization. However, it remained unclear at which stage the pregnancy was terminated. Here we test if MHC-linked cryptic female choice in horses happens during the first days of pregnancy, i.e., until shortly after embryonic entrance into the uterus and before fixation in the endometrium. We exposed estrous mares to one of several unrelated stallions, instrumentally inseminated them with semen of another stallion, and flushed the uterus 8 days later to test for the presence of embryos. In total 68 embryos could be collected from 97 experimental trials. This success rate of 70.1% was significantly different from the mean pregnancy rate of 45.7% observed 17 days after fertilization using the same experimental protocol but without embryo flushing. Embryo recovery rate was not significantly dependent on whether the mares had been socially exposed to an MHC-dissimilar or an MHC-similar stallion. These observations suggest that MHC-linked maternal strategies affect embryo survival mainly (or only) during the time of fixation in the uterus

MHC-correlated preferences in diestrous female horses (Equus caballus).

Genes of the major histocompatibility complex (MHC) have been shown to influence communication in many vertebrates, possibly with context-specific MHC-correlated reactions. Here we test for MHC-linked female preferences in the polygynous horse (Equus caballus) by repeatedly exposing 19 mares to a group of seven sexually experienced stallions. Each mare was tested four times during two consecutive reproductive cycles, twice during estrus and twice during diestrus. Male plasma testosterone concentrations were determined from weekly blood samples, and equine leukocyte antigen (ELA) class I and II alleles were determined serologically at the end of the experiments. Perception of male attractiveness was strongly dependent on estrous cycle: mean preference scores did not correlate for mares in diestrus and estrus and varied more during estrus than during diestrus. We found elevated female interests for MHC-dissimilar stallions, but only during diestrus, not during estrus. Female preferences were not significantly predicted by mean male testosterone plasma concentrations. However, testosterone concentrations changed during the 11 weeks of the experiment. By the end of the experiment, average testosterone concentration was significantly correlated to the average number of MHC alleles the stallions shared with the mares. We conclude that the MHC affects female preferences for stallions, but non-MHC linked male characteristics can overshadow effects of the MHC during estrus

Equine post-breeding endometritis: A review

The deposition of semen, bacteria and debris in the uterus of the mare after breeding normally induces a self-limiting endometritis. The resultant fluid and inflammatory products are cleared by 48 hours post cover. Mares that are susceptible to persistent post-breeding endometritis (PPBEM) have impaired uterine defence and clearance mechanisms, making them unable to resolve this inflammation within the normal time. This persists beyond 48 hours post-breeding and causes persistent fluid accumulation within the uterus. Mares with PPBEM have an increased rate of embryonic loss and a lower overall pregnancy rate than those without the condition. To enhance conception rates, mares at high risk need optimal breeding management as well as early diagnosis, followed by the most appropriate treatment. This article reviews the pathogenesis, diagnosis and treatment of PPBEM and the management of affected mares

Effects of Atrial Fibrillation on the Human Ventricle

Rationale: Atrial fibrillation (AF) and heart failure often coexist, but their interaction is poorly understood. Clinical data indicate that the arrhythmic component of AF may contribute to left ventricular (LV) dysfunction. Objective: This study investigates the effects and molecular mechanisms of AF on the human LV. Methods and Results: Ventricular myocardium from patients with aortic stenosis and preserved LV function with sinus rhythm or rate-controlled AF was studied. LV myocardium from patients with sinus rhythm and patients with AF showed no differences in fibrosis. In functional studies, systolic Ca2+ transient amplitude of LV cardiomyocytes was reduced in patients with AF, while diastolic Ca2+ levels and Ca2+ transient kinetics were not statistically different. These results were confirmed in LV cardiomyocytes from nonfailing donors with sinus rhythm or AF. Moreover, normofrequent AF was simulated in vitro using arrhythmic or rhythmic pacing (both at 60 bpm). After 24 hours of AF-simulation, human LV cardiomyocytes from nonfailing donors showed an impaired Ca2+ transient amplitude. For a standardized investigation of AF-simulation, human iPSC-cardiomyocytes were tested. Seven days of AF-simulation caused reduced systolic Ca2+ transient amplitude and sarcoplasmic reticulum Ca2+ load likely because of an increased diastolic sarcoplasmic reticulum Ca2+ leak. Moreover, cytosolic Na+ concentration was elevated and action potential duration was prolonged after AF-simulation. We detected an increased late Na+ current as a potential trigger for the detrimentally altered Ca2+/Na+-interplay. Mechanistically, reactive oxygen species were higher in the LV of patients with AF. CaMKII (Ca2+/calmodulin-dependent protein kinase IIδc) was found to be more oxidized at Met281/282 in the LV of patients with AF leading to an increased CaMKII activity and consequent increased RyR2 phosphorylation. CaMKII inhibition and ROS scavenging ameliorated impaired systolic Ca2+ handling after AF-simulation. Conclusions: AF causes distinct functional and molecular remodeling of the human LV. This translational study provides the first mechanistic characterization and the potential negative impact of AF in the absence of tachycardia on the human ventricle

Iron in equine semen, seminal plasma and spermatozoa

The essential trace element iron is contained in proteins such as hemoglobin, ferritin, lactoferrin and catalase. The latter is an ubiquitously expressed enzyme that detoxifies hydrogen peroxide. Catalase activities have been determined in stallion semen, spermatozoa and seminal plasma. On the other hand, iron is involved in the production of reactive oxygen species ROS via the Fenton and the Haber Weiss reaction, processes which produce the hydroxyl radical and hydrogen peroxide, respectively. An excess of ROS has been suggested to be the main cause of male infertility. For these reasons, it is of interest to investigate whether iron has an effect on equine sperm chromatin condensation. The iron level of native semen and seminal plasma of 66 stallions was measured by instrumental neutron activation analysis INAA . In 12 of the seminal plasma samples the iron content was below the detection limit of the method. The iron content per 109 sperm was calculated from the difference between the iron level of whole semen and that in the seminal plasma. The sperm count was determined by hemocytometer technique. The extent of sperm DNA denaturation was expressed in terms of DNA fragmentation index DFI by sperm chromatin structure assay SCSA . The iron concentration in semen was strongly correlated with the sperm concentration in semen r 0.85, p lt; 0.0001 . The mean iron level in equine semen and spermatozoa was 11.4 nmol ml and 27 nmol 10 9 sperm, respectively. Due to our best knowledge, this is the first study about iron in equine spermatozoa. Other investigators determined an iron content of 1.9 nmol ml in stallion seminal plasma. This value is consistent with the seminal plasma iron level of 3.2 nmol ml determined in our study. There were no significant correlations between the iron concentration in semen, seminal plasma or spermatozoa and DFI Range p 0.06 to 0.84; r 0.03 to 0.26 . A significant negative correlation was found between the iron dry level in semen and the DFI value r 0.33, p lt; 0.006 . Therefore, iron in semen may be involved in the prevention of chromatin damage. However, the DFI value was not significantly correlated with the iron wet content in semen as well as with the iron levels in spermatozoa or seminal plasma Range p 0.13 to 0.78; r 0.04 to 0.21 . Iron in stallion spermatozoa had no significant effect on sperm chromatin condensation r 0.26, p lt; 0.06 , which is possibly caused by neutralization of the antioxidative action of iron in the form of catalase. Such neutralization might occur by the production of ROS via the Fenton and the Haber Weiss reaction. This is not unlikely as lactoferrin, an iron binding protein present in stallion seminal plasma, catalyzes the production of the hydroxyl radical in vitro in a Fenton type Haber Weiss reaction. It should also be considered that other antioxidative enzymes than catalase might be more important for the protection of the condensed sperm chromatin structur

Zusammenhänge zwischen Alter, Parität, endometrialer Fibrosierung, Frühgraviditätsrate und uteriner Durchblutung bei der Stute

Aim of this study was the examination of relationships between age, parity, incidence of endometrial fibrosis, early pregnancy rate and uterine blood flow in mares. Material and methods: Twenty-two mares were examined between days -2 and 12 (0 = ovulation). Animals were divided into two groups according to age and parity. Mares with an age ranging from 3 to 9 years were characterized as "young" (n = 11 ) and animals with an age of 10 to 19years as "old". Ten of the mares were nulliparous and 12 uni- or pluriparous. Endometrial fibrosis was determined according to criteria by Kenney and Doig (1986). Results: Out of the 22 mares, 13 showed an endometrial fibrosis (category Ma, lib and III, respectively). After insemination with extended semen 8 of the mares became pregnant. The investigations were performed with a colour Doppler sonograph equipped with a 7.0 MHz microconvex-probe. Blood flow was visualized in both uterine arteries. Time-averaged maximum blood flow velocity (TAMV), and vascular-diameter (D) were determined and blood flow volume (VOL) was calculated. VOL values showed similar cyclic changes in all mares (p 0.05). VOL was higher (p < 0.05) in aged, uni- or pluriparous and mares with endometrial fibrosis than in "young", nulliparous and mares without endometrial fibrosis. In contrast to pregnant animals uterine VOL values increased (p < 0.05) in barren mares within 12 hours after insemination. Conclusion and clinical relevance: The results show that the investigation of uterine blood flow by transrectal colour Doppler sonography provides important information concerning the fertility of mares. © 2008 Schattauer GmbH