Stimulation of pulses of 13,14-dihydro-15-keto-PGF2alpha (PGFM) with estradiol-17beta and changes in circulating progesterone concentrations within a PGFM pulse in heifers.
A single physiologic dose (0.1 mg) of estradiol-17beta in sesame-oil vehicle or vehicle alone (n = 8) was given to heifers on day 14 after ovulation to study the effect on circulating 13-14-dihydro-15-keto-PGF2alpha (PGFM), PGFM pulses, and changes in progesterone concentrations within a PGFM pulse. Blood samples were collected hourly for 16 h after treatment. The estradiol group had a greater mean concentration of PGFM, greater number of heifers with PGFM pulses and number of pulses/heifer, and greater prominence of the PGFM pulses. Changes in progesterone concentrations were not detected during the 16 h sampling session in the vehicle group, indicating that the heifers were in preluteolysis. Progesterone decreased after 12 h in the estradiol group, indicating a luteolytic effect of the estradiol-induced PGF secretion as represented by PGFM concentrations. Intrapulse changes in progesterone were detected during a PGFM pulse in the estradiol group (P < 0.006), but not in the vehicle group. Progesterone increased (P < 0.01) between Hours -2 and -1 of an estradiol-induced PGFM pulse (Hour 0 = peak of pulse), decreased (P < 0.004) between Hours -1 and 0, and increased (P < 0.01) or rebounded between Hours 0 and 1. Results were compatible with previous reports of a role for estradiol in the induction of PGFM pulses in cattle and demonstrated intrapulse changes in progesterone concentrations during an induced PGFM pulse.
Ginther
O J
OJ
Eutheria Foundation, Cross Plains, Wisconsin 53528, USA. ginther@vetmed.wisc.edu
Shrestha
H K
HK
Fuenzalida
M J
MJ
Imam
S
S
Beg
M A
MA
D000818:Animals; D002417:Cattle / Q000097:blood*; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000097:blood; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D003341:Luteolysis / Q000097:blood; D010507:Periodicity; D011374:Progesterone / Q000097:blood*; D013997:Time Factors
C008228:15-keto-13,14-dihydroprostaglandin F2alpha; D011374:Progesterone; D004958:Estradiol; D015237:Dinoprost