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The objectives of this study were 1) to determine whether insulin-like growth factor-I (IGF-I) and insulin-like growth factor binding proteins (IGFBPs) were present in seminal plasma of stallions; 2) to compare semen parameters (IGF proteins, sperm numbers, morphology, and motility) from stallions at sexual rest (SR) and when sexually active (SA); 3) to compare semen parameters between stallions with high and low seminal plasma IGF-I concentrations; and 4) to examine the relationship between seminal plasma IGF-I concentrations and fertility parameters of stallions. Ejaculates were collected from stallions at SR (n = 51) and SA (n = 46). Concentrations of IGF-I and IGFBP-2 in seminal plasma samples were determined by radioimmunoassay. Presence of IGFBPs in equine seminal plasma was verified using immunoprecipitation and Western ligand blot procedures. IGF-I, IGFBP-2, and IGFBP-5 were present in equine seminal plasma. Concentrations of IGF-I, IGF-I/protein, total IGF-I, IGFBP-2, IGFBP-2/protein, and total IGFBP-2 were not significantly different (P > or = 0.13) in seminal plasma between stallions at either SR or SA. At SR, stallions with higher seminal plasma IGF-I had more total IGFBP-2 per ejaculate (P < 0.01), more morphologically normal sperm (P = 0.05), and higher first-cycle pregnancy rates (P = 0.02). At SA, stallions with higher seminal plasma IGF-I had fewer cycles per pregnancy (P = 0.02). An association of seminal plasma IGF-I concentration with sperm motility, sperm morphology, and pregnancy rates in bred mares suggests that IGF-I may play a role in sperm function.

Equine spermatozoa induce a uterine inflammatory response characterized by a rapid, transient influx of polymorphonuclear neutrophils (PMNs). Seminal plasma proteins have been shown to modulate the interaction between spermatozoa and PMNs, but a specific protein responsible for this function has not been identified. The objective of this study was to isolate and identify a protein in equine seminal plasma that suppresses binding between spermatozoa and PMNs. Seminal plasma was pooled from five stallions, and proteins were precipitated in 60% (w/v) ammonium sulfate and dialyzed (3500 MW cutoff). Proteins were submitted to a Sephacryl S200 column, and fractions were pooled based on the fraction pattern. Each pool was analyzed for protein concentration and tested for its suppressive effect on PMN/sperm binding. Protein pools with biological activity were submitted to ion-exchange chromatography (diethylaminoethyl [DEAE] Sephadex column) with equilibration buffers containing 0.1-0.5M NaCl. Eluants were pooled, analyzed for protein concentration, and tested for suppressive effects on PMN/sperm binding. Protein distribution and purity were determined by one- and two-dimensional SDS-PAGE, and the purified protein was submitted for sequence analysis and identification. This protein was identified as equine CRISP3 and was confirmed by Western blotting. Suppression of PMN/sperm binding by CRISP3 and seminal plasma was confirmed by flow cytometry (22.08% ± 3.05% vs. 2.06% ± 2.02% vs. 63.09% ± 8.67 for equine seminal plasma, CRISP3, and media, respectively; P < 0.0001). It was concluded that CRISP3 in seminal plasma suppresses PMNs/sperm binding, suggesting that CRISP3 regulates sperm elimination from the female reproductive tract.

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Pferdeheilkunde 24 56 IntroductionIn the past, endometritis was believed to exclusively be the result of bacterial contamination of the uterus (Asbury and Lyle 1993). Treatment strategies were focused on preventing bacteria from entering the uterus, and/or administration of antibiotics. Hughes and Loy (1969) demonstrated that young reproductively sound mares had natural resistance to an experimentally induced infection. They concluded that local components of uterine defense were responsible for the effective and rapid clearance of bacteria in mares with natural resistance to uterine infection. Mares that failed to spontaneously clear the uterus from bacteria were classified as susceptible to persistent endometritis. Subsequent research on uterine defense mechanisms has increased our understanding of the pathophysiology of equine endometritis. Causative agents have been identified, and we have learned to distinguish between uterine infection and a physiological breeding-induced endometritis resulting from uterine exposure to semen (Troedsson et al. 1995a, Troedsson 1999. Additionally, more effective management and treatment protocols have reduced the effect of endometritis on fertility. However, endometritis remains a major clinical problem in brood mare practice. The reasons for this may be that effective management/treatment of "susceptible" mares have resulted in maintaining these mares within our brood mare population, possibly also affecting the gene pool. Breeding-induced endometritisIntrauterine deposition of equine semen causes an inflammatory reaction resulting from spermatozoa (Kotilainen et al. SummaryBreeding-induced endometritis is a physiological reaction to semen. It is an important part of normal sperm transport to the oviduct as well as elimination of excess sperm from the uterus. In 10-15% of brood mares, the normal clearance mechanism fails resulting in a persistent breeding-induced endometritis with severe consequences on fertility. The cause of persistent breeding-induce endometritis is believed to be impaired myometrial activity in response to uterine inflammation. However, disruption of normal breeding activities may also contribute to the condition. Social interaction with a stallion appears to be important to normal uterine contractility after breeding. The presence of seminal plasma in an inseminate has also been shown to be of importance to normal sperm transport and elimination from the female tract, as well as in the modulation of the breeding-induced inflammation. Treatment of persistent breeding-induced endometritis has been focused on assisting the uterus to clear the inflammation in a timely fashion. Post-breeding treatments with oxytocin or prostaglandins and/or uterine lavage at 6-24 hours after breeding have been used by practitioners with good success. Alternative treatments such as the use of corticosteroids, immunostimulants, and acupuncture have recently been suggested to improve uterine clearance and fertility in mares that are susceptible to persistent breeding-induced ...