The distribution of progesterone in body fluids and tissues of the dairy cow

McCracken, John A (1964) The distribution of progesterone in body fluids and tissues of the dairy cow. PhD thesis, University of Glasgow.

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A careful study was carried out of the method of Short (1956a) and Rowlands and Short (1959) for the estimation of progesterone in plasma and in corpora lutea respectively. For bovine plasma it was found necessary to acetylate the first chromatogram eluate with an acetic anhydride/pyridine mixture and subject the residue to a further chromatography step. These additional steps in-creased the specificity of the method for progesterone and at the same time yielded a comparatively pure final product. In addition the incorporation of a radioactive marker to calculate individual recoveries was found to be an advantage in both plasma and luteal samples. Using the above method plasma- progesterone con-centration was measured throughout the oestrous cycle in six normal dairy cows. The general pattern consisted of a gradual rise in progesterone concentration from near zero levels on the day of oestrus (day 1) until day 5 when a more rapid rise occurred up to a level of about 1.0 ug/100 ml plasma on day 9. The level remained at about this value until day 16 when a decline occurred until near zero levels 213 were reached on the subsequent day of oestrus. There appeared to be a considerable variation in the maximum levels attained during mid-cycle in individual cows. The range of values at this time in the six animals used was 0.63 to 1.44 ug/100 ml plasma. The removal of the corpus luteum or ovaries during mid-cycle in the cow resulted in an initial rapid drop in plasma progesterone concentration followed by a more gradual decline, The fact that this occurred after the removal of either the corpus luteum or the ovaries indicated that the residual progesterone level did not originate from ovarian tissue other than the corpus luteum. It was tentatively suggested that the residual level could be duo to a contribution from either the adrenal gland or the body fat depots. The subsequent determination of comparatively high levels of progesterone in the body fat of cows at mid. cycle emphasised the latter as the more likely of the two sources, with the reservation that an adrenal contribution due to surgical stress could not be ruled out completely. The rapid disappearance of injected progesterone from the circulating blood of the cow was in keeping with the observations made in other species. There was evidence to show that this was partly due to catabolism of the progesterone molecule and partly due to uptake by the body tissues, probably the body fat. Furthermore it was shown that renal excretion of progesterone per se did not occur to any appreciable extent. The half life of progesterone in the blood of the cow appeared to be in the order of 6 minutes. Progesterone in the body fat of cows at mid-cycle sac found to be 5 to 10 times that in the plasma and the identification of the progesterone from this source wan confirmed by infra-red analysis and gas/liquid chromatography. In fat from coup early in the cycle, from ovari-atomised cows and from bullocks, progesterone was not present in any measurable quantity. Progesterone was also found in cows milk where it appeared to reflect the levels found in plasma. However, in spite of milk being more available than plasma, owing to its high fat content, it was not considered to be a better source of material for the study of progesterone metabolism in the cow. Plasma and luteal levels of progesterone were studied in a series of 40 cows at 16 and 26 days after 215 insemination. The levels of progesterone in the pregnant and non pregnant animals when slaughtered at 16 days were of the same order, while at 26 days the marked difference between the levels in pregnant and non-pregnant cows could be accounted for by evidence of a recent ovulation in all cows in the latter group. In this series of 40 cows there appeared to be a relationship between the plasma levels and both the luteal weight and progesterone content. The higher blood levels appeared to be associated with the heaviest glands which in general contained more progesterone. Conversely, low blood levels were observed with small glands which generally contained less progesterone. The absolute and relative amounts of 2093 hydroxyprogesterone did not vary significantly among the groups. Progesterone levels were investigated in certain clinical oases made available through the Veterinary Hospital, namely cases of hydrops allantois and oases of retained foetal membranes. However, progesterone levels in these animals did not appear to differ significantly from those found in normal cows.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: W L Weipers
Keywords: Animal sciences
Date of Award: 1964
Depositing User: Enlighten Team
Unique ID: glathesis:1964-73290
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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