Temporal Associations among Pulses of 13,14-Dihydro-15-keto-PGF2alpha, Luteal Blood Flow, and Luteolysis in Cattle1

Abstract

Luteal blood flow was studied in heifers by transrectal color-Doppler ultrasound. Data were normalized to the decrease in plasma progesterone to <1 ng/ml (Day 0 or Hour 0). Blood flow in the corpus luteum (CL) was estimated by the percentage of CL area with color flow signals. Systemic prostaglandin F2alpha (PGF) treatment (25 mg; n=4) resulted in a transient increase in CL blood flow during the initial portion of the induced decrease in progesterone. Intrauterine treatment (1 or 2 mg) was done to preclude hypothetical secondary effects of systemic treatment. Heifers were grouped into responders (luteolysis; n=3) and nonresponders (n=5). Blood flow increased transiently in both groups; induction of increased blood flow did not assure the occurrence of luteolysis. A transient increase in CL blood flow was not detected in association with spontaneous luteolysis when examinations were done every 12 h (n=6) or 24 h (n=10). The role of PGF pulses was studied by examinations every hour during a 12-h window each day during expected spontaneous luteolysis. At least one pulse of 13,14-dihydro-15-keto-PGF2alpha (PGFM) was identified in each of six heifers during the luteolytic period (Hours -48 to -1). Blood flow increased (P<0.02) during the 3-h ascending portion of the PGFM pulse, remained elevated for 2 h after the PGFM peak, and then decreased (P<0.03) to baseline. Results supported the hypothesis that CL blood flow increased and decreased with individual PGFM pulses during spontaneous luteolysis.

Follicle and corpus luteum size and vascularity as predictors of fertility at the time of artificial insemination and embryo transfer in beef cattle

“…For CL with cavity, the diameter and area of the cavity was subtracted from the total area (Kastelic et al 1990). The percentage of POF wall and luteal tissue with vascular signals was determined subjectively by watching the color Doppler video clip, as previously described (Ginther et al 2007). Experiment 1.…”

“…Near ovulation, was shown that an extensive vascularity is formed in the follicular wall until the ovulation occurs (Geva & Jaffe 2000, Reisinger et al 2007). Subjective and objective methods are validated and can be used to measure follicular vascularity in cows and mares (Ginther et al 2007). Previous works showed that follicles with greater diameter resulted in also greater pregnancy rates (Sá Filho et al 2010a).…”

“…Measurement of CL vascularity was suggested as a diagnosis technique for early pregnancy, but the early detection of pregnancy by evaluation of CL vascularity did not appeared to be a specific and sensitive method (Utt et al 2009). The physiologic aspects of CL vascularity by ultrasonography during formation and lysis were previously described in cows (Acosta et al 2003, Acosta & Miyamoto 2004, Miyamoto et al 2005, Ginther et al 2007), using objective and subjective analyses (Ginther et al 2007). The corpus luteum vascularity is immediately constituted after ovulation (Reynolds et al 2000), and CL vascularity is associated with its functionality (Bollwein et al 2002b).…”

Ovarian and PGF2α responses to stimulation of endogenous PRL pulses during the estrous cycle in mares

“…Fluctuations of PRL, PGFM, LH, and FSH concentrations were evaluated to detect pulses during Hours 0 to 8, as described [1]. When the coefficient of variation (CV) of the values comprising a fluctuation from beginning to ending nadirs was at least three times greater than the mean intra-assay CV, the fluctuation was considered to be a pulse.…”

“…Assay of plasma concentrations of progesterone (P4) and transrectal ultrasonic evaluation of the CL and percentage of CL with color-Doppler blood flow signals can be used to evaluate the CL in large animals [1,2]. In mares, the average day of transition from preluteolysis to luteolysis is Day 14 (Day 0 ϭ ovulation), based on collection of hourly blood samples [3].…”