Regulation of frequency of luteinizing hormone pulses by magnitude of acute change in circulating concentration of progesterone of female cattle

The hypothesis was the greater the magnitude of acute increase in circulating concentration of progesterone of female cattle, the greater the acute inhibitory effect on frequency of pulsatile LH release. From Day 0 to 4 of the treatment period, females without functional corpora lutea were treated w...

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Bibliographic Details
Published in:Animal reproduction science 2004-09, Vol.84 (3), p.279-291
Main Authors: Fike, K.E, Kojima, F.N, Lindsey, B.R, Bergfeld, E.G.M, Quintal-Franco, J.A, Melvin, E.J, Zanella, E.L, Wehrman, M.E, Kinder, J.E
Format: Article
Language:English
Subjects:
Animals
Cattle - blood
Cattle - physiology
Cattle-endocrinology
Estradiol - blood
Estradiol - physiology
Estrous Cycle - physiology
Estrus Synchronization
Female
Least-Squares Analysis
Luteinizing Hormone - blood
Luteinizing Hormone - physiology
Luteinizing Hormone - secretion
Progesterone
Progesterone - blood
Progesterone - physiology
Radioimmunoassay - veterinary
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Summary:The hypothesis was the greater the magnitude of acute increase in circulating concentration of progesterone of female cattle, the greater the acute inhibitory effect on frequency of pulsatile LH release. From Day 0 to 4 of the treatment period, females without functional corpora lutea were treated with varying doses of progesterone to result in varying concentrations of progesterone within the typical physiological range in blood. From Day 4 to 7, cattle were treated with a single dose of progesterone to achieve a similar circulating concentration of progesterone among all females in the study. Therefore, from Day 0 to 4 relative to Day 4 to 7 of the treatment period, females had a: (1) large (3.1 ng/ml), (2) moderate (2.5 ng/ml), or (3) small (0.5 ng/ml) increase in concentration of progesterone in blood. Frequency of LH pulses was greater ( P
ISSN:0378-4320
1873-2232
DOI:10.1016/j.anireprosci.2004.02.002