Intrapulse changes in progesterone and LH concentrations and luteal blood flow during an estradiol-induced pulse of a metabolite of prostaglandin F2alpha in heifers.
Physiologic doses (0.1 mg followed by 0.05 mg 1h later) of estradiol-17beta in sesame-oil vehicle or vehicle alone (n=6/group) were given to heifers on day 14 after ovulation (preluteolysis) to study the effect of estradiol (E2) on circulating 13,14-dihydro-15-keto-PGF2alpha (PGFM) and on PGFM pulses. Blood samples were collected hourly for 10h after the 0.1-mg treatment. The E2 group had an increase (P<0.03) in PGFM concentration by 4h and greater (P<0.0001) prominence of the PGFM pulses. Changes in progesterone and LH concentrations and luteal blood flow within a PGFM pulse were characterized. Within a PGFM pulse in the E2 group, progesterone decreased (P<0.04) between Hours -2 and 0 (ascending portion; Hour 0=peak of pulse) and increased (P<0.04) between Hours 0 and 2 (descending portion). Intrapulse changes in progesterone were not detected in the vehicle group. Concentration of LH in the E2 group increased (P<0.05) between Hours -1 and 1 and in the vehicle group decreased (P<0.03) between Hours -1 and 0 and increased (P<0.06) between Hours 0 and 1. The percentage of luteal area with blood-flow signals increased (P<0.02) between Hours 0 and 1 in the E2 group, and there were no other differences between hours in either group. Results were consistent with reports of changes in progesterone concentration within a PGFM pulse in cattle and demonstrated intrapulse changes in LH concentration and luteal blood flow during an E2-induced PGFM pulse.
Imam
S
S
Eutheria Foundation, Cross Plains, WI 53528, USA.
Shrestha
H K
HK
Beg
M A
MA
Ginther
O J
OJ
D000818:Animals; D002417:Cattle; D003338:Corpus Luteum / Q000098:blood supply / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology; D015237:Dinoprost / Q000031:analogs & derivatives* / Q000097:blood / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D034461:Luteinization / Q000187:drug effects; D007986:Luteinizing Hormone / Q000097:blood*; D009994:Osmolar Concentration; D010060:Ovulation / Q000097:blood / Q000187:drug effects; D011374:Progesterone / Q000097:blood*; D011673:Pulsatile Flow / Q000187:drug effects / Q000502:physiology; D012039:Regional Blood Flow / Q000187:drug effects* / Q000502:physiology
C008228:15-keto-13,14-dihydroprostaglandin F2alpha; D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone; D015237:Dinoprost