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12 January 2011 Pulsatility and Interrelationships of 13,14-Dihydro-15-Keto-PGF2alpha (PGFM), Luteinizing Hormone, Progesterone, and Estradiol in Heifers
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Abstract

Temporality among episodes of a prostaglandin F2alpha metabolite (PGFM), progesterone (P4), luteinizing hormone (LH), and estradiol (E2) were studied during preluteolysis and luteolysis. A vehicle group (n = 10) and a group with an E2-induced PGFM pulse (n = 10) were used. Blood sampling was done every 0.25 h for 8 h. An episode was identified by comparing its coefficient of variation (CV) with the intra-assay CV. Pulsatility of PGFM, P4, LH, and E2 in individual heifers was inferred if the autocorrelation functions were different (P < 0.05) from zero. About four nonrhythmic fluctuations of PGFM/8 h were superimposed on PGFM pulses. Pulsatility was detected for LH but not for P4 and E2. A transient increase in P4 was not detected during the ascending portion of a PGFM pulse. Progesterone decreased (P < 0.003) during Hours −1.25 to −0.50 of the PGFM pulse (Hour 0 = peak) and ceased to decrease temporally with an increase (P < 0.05) in LH. Maximum P4 concentration occurred 0.25 h after an LH pulse peak, and an increase (P < 0.005) in E2 began at the LH peak. Nadirs of LH pulses were greater (P < 0.05) and the nadir-to-nadir interval was shorter (P < 0.003) in the E2 group, which is consistent with reported characteristics during luteolysis. The results did not support the hypothesis of a transient P4 increase early in a PGFM pulse and indicated a balance between a luteolytic effect of PGF and a luteotropic effect of LH within the hours of a PGFM pulse.

O.J. Ginther, Maria J. Fuenzalida, Minhaj A. Hannan, and Mohd A. Beg "Pulsatility and Interrelationships of 13,14-Dihydro-15-Keto-PGF2alpha (PGFM), Luteinizing Hormone, Progesterone, and Estradiol in Heifers," Biology of Reproduction 84(5), 922-932, (12 January 2011). https://doi.org/10.1095/biolreprod.110.089953
Received: 23 November 2010; Accepted: 1 January 2011; Published: 12 January 2011
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