Dehydroepiandrosterone secretion in dairy cattle is episodic and unaffected by ACTH stimulation

Autor: Laura Da Dalt, Lieta Marinelli, Gianfranco Gabai, Mariacristina Merlo, Giuseppe Bertoni, Erminio Trevisi
Jazyk: angličtina
Rok vydání: 2007
Předmět:
endocrine system
medicine.medical_specialty
Time Factors
Hydrocortisone
medicine.drug_class
Endocrinology
Diabetes and Metabolism
Narcotic Antagonists
Luteolysis
Dehydroepiandrosterone
Stimulation
(+)-Naloxone
Luteal phase
Injections
Intramuscular
Adrenal stimulation
Endocrinology
Adrenocorticotropic Hormone
Dehydroepiandrosterone secretion
Internal medicine
Placenta
polycyclic compounds
Medicine
Animals
Lactation
Milk Ejection
DHEA
skin and connective tissue diseases
business.industry
Dehydroepiandrosterone Sulfate
Naloxone
dairy cattle
Dairy cows
Settore AGR/19 - ZOOTECNICA SPECIALE
Stimulation
Chemical
medicine.anatomical_structure
Data Interpretation
Statistical
Secretagogue
Cattle
Female
business
Secretory Rate
human activities
hormones
hormone substitutes
and hormone antagonists
Opioid antagonist
Popis: This paper describes the episodic release and response to adrenal stimulation of cortisol and dehydroepiandrosterone (DHEA) in cows. Observations made in samples taken every 10 min for 8 h (experiment 1) showed that plasma DHEA was significantly greater (P < 0.001) than DHEA-S, and release of these steroids was episodic and variable between animals (P < 0.01). No relationship was found between DHEA and cortisol. Significant (P < 0.001) DHEA-sulphate (DHEA-S) versus cortisol (R = −0.264) and DHEA-S versus DHEA (R = 0.200) correlations were found. DHEA and DHEA-S were not affected by a single ACTH challenge (experiment 2). In experiment 3, cortisol and DHEA secretions in response to prolonged ACTH administration (every 12 h for 6 days) were studied. On day 7, the episodic cortisol and DHEA release and response to the opioid antagonist naloxone were studied in blood samples taken every 10 min for 8 h. Animals were injected with naloxone after 4 h. A significant increase (P < 0.05) in mean circulating DHEA and DHEA pulse amplitude was observed during frequent sampling following ACTH treatment. DHEA and DHEA-S plasma concentrations were not affected following luteal regression (experiment 4). The effect of milk secretion around parturition on DHEA secretion was studied in dry and continuously milked cows (experiment 5). Plasma DHEA was significantly lower (P < 0.05) in milked cows. In the cow, ACTH is not an important DHEA secretagogue. Adrenal contribution to plasma DHEA is scarce. Likely, the placenta is the most important source of DHEA, and the lactating mammary gland can affect circulating DHEA levels. Investigation about the DHEA biological role in cows should be focused around parturition.
Databáze: OpenAIRE
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