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PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
5
pubmed:dateCreated
2004-8-4
pubmed:abstractText
In experiment I, the effect of i.m. oxytocin (OT) injection (50 IU) on OT blood pattern was tested. Blood samples from 6 cows were collected for 2 h after OT injection either with or without milking. To test the effect of i.m. OT injection (50 IU) on milk ejection efficiency, intramammary pressure (IMP) was measured in 13 cows (experiment II). Milk ejection was induced by manual teat stimulation. After IMP increased and reached a plateau, OT was injected. In experiment III, the effect of chronic OT treatment on mammary gland sensitivity and endogenous OT release was tested. For 19 d, cows were i.m. injected at each milking with 50 IU OT (n = 13) or 5 mL of NaCl 0.9% (n = 14) 1 min before the start of udder preparation. To test mammary gland sensitivity, IMP recording was performed after a long (11 h, 7 OT cows, and 7 NaCl cows) and a short (3 h, 6 OT cows, and 7 NaCl cows) milking interval at d -1 and d 18. To test the effect of withdrawal of chronic i.m. treatment on OT release, blood sample collection was performed during evening milking at d 0 and d 19. Intramuscular oxytocin injection (experiment I) caused elevated OT blood levels observed at least for 2 h and showed an even more pronounced effect when milking was also performed. Intramuscular OT injection after teat stimulation (experiment II) caused additional milk ejection but only in 6 out of 13 cows. Withdrawal of chronic OT treatment (experiment III) did not reduce OT release during milking. However, ejection time was prolonged during OT infusion after a long milking interval. Ejection pressure tended to be lower after a short milking interval. It seems that the reduction of spontaneous milk removal after chronic OT treatment was due to reduced contractibility of myoepithelial cells in the mammary gland at a physiological range of OT concentrations.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0022-0302
pubmed:author
pubmed:issnType
Print
pubmed:volume
87
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1236-44
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
2004
pubmed:articleTitle
Effects of oxytocin administration on oxytocin release and milk ejection.
pubmed:affiliation
Physiology Weihenstephan, Technical University Munich, Weihenstephaner Berg, Freising, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't