Milk plasmin during bovine mammary involution that has been accelerated by estrogen

The purpose of this study was to evaluate whether the plasminogen and plasmin system within bovine mammary secretions was influenced by an estrogen treatment that was used to accelerate mammary tissue involution. Holstein cows were injected with 4 ml of ethanol excipient (n = 21) or 15 mg of estradi...

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Bibliographic Details
Published in:Journal of dairy science 1997-08, Vol.80 (8), p.1561-1568
Main Authors: Athie, F, Bachman, K.C, Head, H.H, Hayen, M.J, Wilcox, C.J
Format: Article
Language:English
Subjects:
ACTIVIDAD ENZIMATICA
ACTIVITE ENZYMATIQUE
ANIMAL TISSUES
Animals
Biological and medical sciences
Cattle - physiology
CONTEO DE CELULAS SOMATICAS
DAIRY COWS
DRY PERIOD
ENZYME PRECURSORS
ENZYMIC ACTIVITY
Estradiol - pharmacology
ESTROGENOS
Female
Fibrinolysin - metabolism
GLANDE MAMMAIRE
GLANDULAS MAMARIAS
Hormones. Endocrine system
LACTACION
LACTATION
Lactation - physiology
LAIT
LECHE
MAMMARY GLANDS
Mammary Glands, Animal - physiology
Medical sciences
MILK
Milk - enzymology
NUMERATION CELLULAIRE SOMATIQUE
OESTROGENE
OESTROGENS
PERIODE DE TARISSEMENT
PERIODO DE SECADO
Pharmacology. Drug treatments
PLASMIN
PLASMINA
PLASMINE
PLASMINOGEN
Plasminogen - metabolism
PRECURSEUR D'ENZYME
PRECURSORES DE ENZIMAS
Pregnancy
PROTEOLISIS
PROTEOLYSE
PROTEOLYSIS
RATIOS
SOMATIC CELL COUNT
TEJIDOS ANIMALES
Time Factors
TISSU ANIMAL
VACAS LECHERAS
VACHE LAITIERE
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Summary:The purpose of this study was to evaluate whether the plasminogen and plasmin system within bovine mammary secretions was influenced by an estrogen treatment that was used to accelerate mammary tissue involution. Holstein cows were injected with 4 ml of ethanol excipient (n = 21) or 15 mg of estradiol-17 beta (n = 23) on each of the 4 d that preceded final milk removal. Dates of final milk removal (d 0) were designated as 60 d prior to expected dates of calving. Each mammary quarter was sampled once to collect secretions that corresponded to d 0, 3, 11, and 25 or d 1, 7, 18, and 30 of the dry period. Concentrations of plasminogen, plasmin, and somatic cells in secretions increased earlier for treated cows than for control cows. The ratio of plasminogen to plasmin in secretions decreased earlier for treated cows than for control cows. These responses support the suggestion that the plasminogen and plasmin system is involved in the involution of bovine mammary tissue. Estrogen treatment increased the activation of plasminogen, which was evidenced by a precipitous decrease in the ratio of plasminogen to plasmin that occurred as concentrations of plasminogen and plasmin increased. The activation of plasminogen likely contributed to the increased rate of mammary tissue involution that was effected by exogenous estrogen. Endogenous estrogen secreted by the developing fetal and placental unit might mediate, in part, the gradual involution that occurs during lactation
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(97)76086-7