Browsing by Subject "ESTROUS-CYCLE"

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  • Montserrat Rivera del Alamo, Maria; Reilas, Tiina; Galvao, Antonio; Yeste, Marc; Katila, Terttu (2018)
    Treatment with intrauterine devices (IUD) prolongs luteal phases in mares, but the mechanism for this has not been fully elucidated. The aims of the present study were to examine how IUDs affect the uterus to induce longer luteal phases, particularly the role of cyclooxygenase-2 (COX-2) in the maintenance of the corpus luteum (CL). Twenty-seven reproductively normal mares were included: 12 were inseminated (AI), and 15 were fitted with IUDs. Blood samples for progesterone were obtained on Days 0, 3, 5, 7, 9, 11, 13, 14, and 15 (relative to day of ovulation). The groups were further divided into non-pregnant (AI-N, n = 4), pregnant (AI-P, n = 8), normal (IUD-N, n = 8) and prolonged luteal phase (IUD-P, n = 7) based on ultrasonic examinations and serum progesterone concentrations on Days 14 and 15. Blood sampling to quantify the PGF(2 alpha) metabolite (PGFM) was performed through a catheter hourly from 15:00 to 20:00 h on Day 14, and from 6:00 until 13:00 h on Day 15. On Day 15, a low-volume uterine lavage followed by an endometrial biopsy was performed. Estradiol concentration in the Day 15 serum and lavage fluid was determined, while the abundance of COX-2 was evaluated in the biopsy specimens using western blotting (WB) and irnmunohistochemistry (IHC). All pregnant mares were negative for COX-2 in IHC samples and 5 of 8 were negative in WB samples while all mares of the IUD-N group were positive for COX-2. Of the seven mares in the IUD-P group, five and four were negative for COX-2 with the IHC and WB samples, respectively. The results from this study indicate that IUDs, when effective, suppress COX-2, leading to the inhibition of PGF2 alpha release and maintenance of CL.
  • Grahofer, Alexander; Björkman, Stefan; Peltoniemi, Olli (2020)
  • Haen, Silke M.; Heinonen, Mari; Bjorkman, Stefan; Soede, Nicoline M.; Peltoniemi, Olli A.T. (2020)
    Abstract We studied luteinizing hormone (LH) pulsatility and episodic progesterone release of the corpus luteum (CL) on Day 11 and Day 21 in inseminated gilts and aimed to establish a relationship between these two hormones. Blood was collected at 15-minute intervals for 12 hours on Days 11, 16, and 21 from a vena cava caudalis catheter. At euthanasia eight gilts were pregnant and six gilts were not pregnant. Progesterone parameters (basal, mean, pulse frequency, and pulse amplitude) did not differ between pregnant and non-pregnant gilts on Day 11, LH pulse frequency and amplitude tended to differ (p = 0.07 and p = 0.079). In pregnant gilts basal and mean progesterone, progesterone pulse amplitude and frequency declined significantly from Day 11 to Day 21 (p <0.05). A significant decline was also seen in the LH pulse amplitude from Day 11 to Day 21 (p <0.05). None of the LH pulses was followed by a progesterone pulse within 1 hour on Day 21. On Day 11 and Day 21 appeared a synchronicity in the LH pulse pattern, as there were two or three LH pulses in 12 hours and these LH pulses appeared in the same time window. We conclude that on Day 11 and Day 21 of pregnancy in gilts progesterone pulses do not follow an LH pulse within one hour. Further we demonstrated that the successful or not successful formation of a CL of pregnancy is independent of progesterone release on Day 11 after insemination. We confirmed the decline of progesterone from Day 11 to Day 21 in the vena cava caudalis and could demonstrate that this decline is partly due to lower progesterone pulse amplitude and frequency and that the decline occurs simultaneously with a decline in LH pulse amplitude.