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Neurotransmitter and Neurohormonal Regulation of Oxytocin Secretion in Lactation a
Author(s) -
CROWLEY W. R.,
PARKER S. L.,
STRONG W. E. ARM,
SPINOLO L. H.,
GROSVENOR C. E.
Publication year - 1992
Publication title -
annals of the new york academy of sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.712
H-Index - 248
eISSN - 1749-6632
pISSN - 0077-8923
DOI - 10.1111/j.1749-6632.1992.tb34362.x
Subject(s) - oxytocin , neurotransmitter , secretion , endocrinology , medicine , neurotransmitter agents , chemistry , neuroscience , biology , central nervous system
The physiology of the milk ejection reflex and aspects of its neural control in the lactating rat have been extensively reviewed. I4 Brief pulses of oxytocin (OT) secretion from the neurohypophysis occur at frequent intervals throughout most of the day in response to the nursing stimulation from the offspring. Mechanoreceptors within the teat, mammary parenchyma, and skin overlying the mammary gland transmit the suckling stimulus to ascending neuronal pathways, which ultimately gain access to the OT neurosecretory cells that release the peptide. OT acts at specific receptors to cause contraction of the myoepithelial cells that are localized on the surface of the mammary alveoli and along the mammary ducts. When those on the alveoli contract, the compression of the cells raises intra-alveolar pressure. Contraction of myoepithelial cells on the ducts shortens and widens the ducts, thereby reducing resistance to the flow of milk through the duct system. The temporal pattern of individual episodes of OT release has been characterized in the urethane-anesthetized rat.s Abrupt increases in plasma OT concentrations of 2to 2.5-fold occur in close association with the elevation in intramammary pressure, followed by a return to baseline concentrations within two to three minutes. When female rats are suckled by their offspring after several hours of separation, a number of characteristic hormonal responses are observed in the temporal sequence