Intrapulse changes in progesterone and LH concentrations and luteal blood flow during an estradiol-induced pulse of a metabolite of prostaglandin F2α in heifers

• Published in: Animal reproduction science Vol. 121; no. 1; pp. 34 - 38
• Main Authors: Imam, S., Shrestha, H.K., Beg, M.A., Ginther, O.J.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-2010; [Amsterdam]: Elsevier Science
• Subjects: blood flow; Cattle; corpus luteum; dosage; dose response; Estradiol; heifers; hormonal regulation; hormone secretion; luteinizing hormone; luteolysis; normal values; ovaries; ovulation; Progesterone; Prostaglandin F2α; prostaglandins; reference standards; temporal variation; Progesterone; LH; Cattle; Estradiol; Prostaglandin F2α
• ISSN: 0378-4320; 1873-2232
• DOI: 10.1016/j.anireprosci.2010.05.009

Physiologic doses (0.1
mg followed by 0.05
mg 1
h later) of estradiol-17β 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-PGF2α (PGFM) and on PGFM pulses. Blood samples were collected hourly for 10
h after the 0.1-mg treatment. The E2 group had an increase (
P
<
0.03) in PGFM concentration by 4
h 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.