Temporal associations among pulses of 13,14-dihydro-15-keto-PGF2alpha, luteal blood flow, and luteolysis in cattle.
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.
Ginther
O J
OJ
Eutheria Foundation, Cross Plains, Wisconsin 53528, USA. ginther@svm.vetmed.wisc.edu
Silva
L A
LA
Araujo
R R
RR
Beg
M A
MA
D000818:Animals; D002417:Cattle; D003338:Corpus Luteum / Q000098:blood supply* / Q000187:drug effects; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000097:blood / Q000494:pharmacology; D005260:Female; D003341:Luteolysis / Q000502:physiology*; D010060:Ovulation; D011374:Progesterone / Q000097:blood; D012039:Regional Blood Flow; D018615:Ultrasonography, Doppler, Color
C008228:15-keto-13,14-dihydroprostaglandin F2alpha; D011374:Progesterone; D015237:Dinoprost