Cyril Stephen

The localization of kisspeptin and kisspeptin receptor in the canine ovary during different stages of the reproductive cycle

Kisspeptin is a neuropeptide involved in the hypothalamic regulation of reproduction in many species. Recent studies have revealed kisspeptin within the ovaries of rats, Siberian hamsters and humans, indicating a local role in reproduction. However, the role of kisspeptin in the ovary is poorly understood in the bitch. This study investigated the presence and location of kisspeptin protein (KISS1) and kisspeptin receptors (KISS1R) in the canine ovary during different stages of the reproductive cycle (pre-pubertal, anoestrus and cycling) by means of immunohistochemical staining. Ovaries from 24 bitches presented at local veterinary clinics for routine ovariohysterectomy were collected and grouped based on reproductive stage (pre-pubertal, anoestrus and cycling (proestrus, oestrus and dioestrus)). The presence or absence of immunoreactive KISS1 and KISS1R was recorded without any quantification of the levels of expression within cells. Immunoreactive KISS1 was found in the oocytes during all stages of the oestrous cycle, in the granulosa cells during all stages except anoestrus and in the corpus luteum (CL) during dioestrus. KISS1 was absent in the ovaries of pre-pubescent bitches. Immunoreactive KISS1R were consistently found in the oocytes, primordial follicles, the granulosa cells and CL in cycling bitches. The finding of KISS1R in the granulosa cells is suggestive that kisspeptin and progesterone may be linked as this pattern of staining is seen in animals that show preovulatory luteinisation of follicles during oestrus, KISS1R were also observed in the ovaries of pre-pubescent and anoestrous bitches, suggesting a possible role of kisspeptin in oocyte proliferation, development and maturation of granulosa cells, and progesterone production. This study provides a starting point for the establishment of a canine model for kisspeptin regulation within the ovary.

Assessment of uterine luminal pH in mares and the effect of dilute vinegar lavage on uterine luminal pH and endometrial health

Uterine luminal pH has been demonstrated to be a valid indicator of uterine health in species such as cattle and sheep. However, research regarding uterine luminal pH in equines is lacking. The objectives of this study were to assess uterine luminal pH in mares during the estrous cycle, and evaluate the effect of dilute vinegar lavage on both uterine luminal pH and endometrial health. The study was conducted using a randomized block design in which eight mares (four Thoroughbred and four Standardbred) were aged matched then randomly assigned to two groups. Endometrial biopsies were taken from each mare prior to trial commencement. The treatment group (nu202f=u202f4; 1 Thoroughbred, 3 Standardbreds) received a uterine lavage of one liter dilute vinegar (20u202fmL of vinegar in 1u202fL saline) every second day during each estrus period throughout the trial. Control group mares did not receive a uterine lavage. Uterine luminal pH measurements were recorded in all mares in both groups for a period of up to 10u202fmin immediately prior to lavage (0u202fh), one hour and 24u202fh post lavage (same time points in control group mares as if they had been treated). Diestrus uterine luminal pH measurements were recorded once between days 6-10 post-ovulation. Endometrial biopsies were repeated from all mares at trial completion. Mean uterine luminal pH ranged from pH 5.3 to 7.6 and was significantly lower during diestrus compared to estrus (Pu202f<u202f0.001). Regression analysis indicated that this variation in pH was best explained by estrous cycle day, with uterine luminal pH increasing by a mean of 0.03 units each day (Pu202f<u202f0.001) from 6 to 10 days post-ovulation through to ovulation. Uterine lavage with dilute vinegar did not significantly affect uterine luminal pH (Pu202f>u202f0.05). A scoring system to quantify the abundance of cell types in the endometrial biopsies showed that mares in the treatment group had a significant decrease in polymorphonuclear cell abundance between pre- and post-trial biopsies (Pu202f=u202f0.03). Mares in the treatment group also had a significant decrease in lymphocyte, plasma cell and eosinophil cell abundance (Pu202f=u202f0.05). Although dilute vinegar lavage was not associated with a significant change in uterine luminal pH, it was associated with a significant improvement in endometrial biopsy scores. Because the control group did not receive a uterine lavage, further research is required to determine if this significant improvement results from the addition of dilute vinegar, or the uterine lavage itself.