ABSTRACT
Sperm-neutrophil binding is an important facet of breeding and significantly impacts fertility. While a specific seminal plasma protein has been found to reduce this binding and improve fertility (CRISP-3), additional molecule(s) appear to promote binding between defective sperm and neutrophils. Recent work has suggested one of these proteins is lactoferrin (LF), an 80 kDa iron-binding protein found throughout the body, but the purity of the protein was not confirmed. It is unknown if LF binds to sperm selectively based on viability, and if receptors for LF are located on equine sperm. To evaluate this, we attempted to purify equine seminal LF from five stallions (n = 5), biotinylate LF, and evaluate potential binding site(s) on spermatozoa. LF was consistently associated with superoxide dismutase (SOD-3), and all attempts to separate the two proteins were unsuccessful. Flow cytometric and microscopic analyses were used to compare LF/SOD-3 binding to viable and nonviable spermatozoa. Additionally, various methods of biotinylation were assessed to optimize this methodology. Biotinylation of seminal plasma protein was an effective and efficient method to study seminal plasma protein properties, and the binding site for LF/SOD-3 was found to be broadly localized to the entire sperm cell surface as well as selective towards nonviable/defective sperm. Although we were not able to determine if the binding to equine spermatozoa was through LF or SOD-3, we can conclude that equine seminal LF is tightly bound to SOD-3 and this protein complex binds selectively to nonviable spermatozoa, possibly to mark them for elimination by neutrophil phagocytosis.
ABSTRACT
Reproductive aging must be well understood to optimize the reproductive management of older mares and to predict their reproductive life-span. The objectives of this study were to: 1) examine age-related differences in follicular dynamics, endocrine profiles, and primordial follicle counts, 2) evaluate the influence of antral follicle count (AFC) on age-related changes in follicular parameters, and 3) determine the influence of diestrous ovulations on the estrous cycle. Young (3-8yr; n = 10), middle-aged (9-18 yr; n = 16), and old (>18 yr; n = 19) light horse mares were examined with transrectal ultrasonography to monitor follicular growth over two consecutive estrous cycles. Jugular blood samples were taken and plasma progesterone and FSH concentrations were determined by an enzyme immunoassay and radioimmunoassay, respectively. Both interovulatory intervals and follicular phases were longer and the day of follicle deviation occurred later in aged mares. Furthermore, older mares had a tendency to ovulate smaller follicles. Neither follicular growth rate, the number of ovulations nor the length of luteal phase was influenced by mare age. Interestingly, as mare age increased, mares with low AFC had longer interovulatory intervals and follicular phases than mares with medium or high AFC. In addition, the number of primordial follicles declined with an increase in mare age but varied considerably between mares of the same age. Progesterone concentrations were positively influenced by age, whereas FSH concentrations were not, despite that FSH concentrations appeared higher in aged mares during the follicular phase. Estrous cycles with a diestrous ovulation had a longer interovulatory interval as well as a longer follicular and luteal phase while day of deviation occurred later. Progesterone concentrations were significantly higher on day 14 and 16 in estrous cycles with a diestrous ovulation than without a diestrous ovulation. In conclusion, aging in mares is associated with changes in follicular parameters which in turn are closely linked to differences in antral follicle count suggesting a relationship with ovarian reserve. Therefore, determination of antral follicle counts in aged mares can provide valuable information about the reproductive aging process. Finally, diestrous ovulations have a significant influence on different estrous cycle parameters.
Subject(s)
Aging/physiology , Estrous Cycle/physiology , Horses/physiology , Ovarian Follicle/physiology , Ovulation/physiology , Animals , FemaleABSTRACT
PROBLEM: Currently, placentitis, an important cause of late pregnancy loss in mares, is diagnosed by clinical signs and ultrasonography. Acute phase proteins (APP) are mainly produced and secreted by the liver in response to acute inflammatory stimuli. We hypothesized that APP are increased in mares with placentitis. METHOD OF STUDY: Concentrations of serum amyloid A (SAA), haptoglobin (Hp), fibrinogen (Fb), and white blood cell counts (WBC) were determined in plasma of mares with experimentally induced placentitis and gestationally age-matched control mares. Placentitis was induced via intracervical inoculation of Streptococcus equi subspecies zooepidemicus, a common isolate from clinical cases of bacterial placentitis. Concentrations of SAA and Hp were also determined in the 10 days pre-partum in normal mares. RESULTS AND CONCLUSION: Mares with placentitis aborted within 5-25 days after inoculation. Concentrations of SAA and Hp rapidly increased subsequent to experimental induction of placentitis and remained increased until abortion. Neither Fb nor WBC appeared to be useful markers for placentitis. Parturition did not trigger increase in either SAA or Hp in normal foaling mares.
