Linked Life Data

10718931

Source:http://linkedlifedata.com/resource/pubmed/id/10718931

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
4
pubmed:dateCreated
2000-5-9
pubmed:abstractText
In pregnancy, endogenous opioids inhibit enhanced basal and stressor-stimulated oxytocin neurone activity and secretion. By contrast, stress responses of the hypothalamo-pituitary-adrenal (HPA) axis are reduced in pregnancy. We investigated whether the high levels of oestradiol and progesterone of pregnancy could induce these changes. Silastic capsules containing oestradiol or progesterone (or control capsules) were implanted s.c. in virgin female rats for 16 or 17 days, with or without progesterone removal on day 15 to mimic the progesterone withdrawal seen at the end of pregnancy. Plasma concentrations of oxytocin, adrenocorticotrophic hormone (ACTH) and corticosterone were measured in jugular vein blood samples from conscious rats. Under basal conditions, naloxone (5 mg/kg) increased oxytocin secretion in all groups, but had no greater effect in sex-steroid treated rats, and did not induce Fos expression in the supraoptic nucleus. Forced swimming, a stressor, increased oxytocin secretion at 5 min in vehicle-injected controls, and this response was slightly attenuated in the sex-steroid treated groups. Pretreatment with naloxone greatly enhanced the response in the sex-steroid treated rats, and was less effective in the controls. In rats treated with oestradiol alone, naloxone prolonged the response. Thus, the combined sex-steroid treatment enhanced the responsiveness of oxytocin neurones to the stressor, while simultaneously restraining oxytocin secretion via endogenous opioid inhibition. In the same rats, ACTH and corticosterone secretion was also stimulated by the stressor, but the hypothalamo-pituitary-adrenal (HPA) axis response was not attenuated in sex-steroid treated rats. Naloxone weakly reduced the HPA axis response in controls and was ineffective in the sex-steroid treated rats. We conclude that oestradiol and progesterone may be responsible for inducing the opioid restraint and enhanced oxytocin neurone responsiveness in pregnancy.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0953-8194
pubmed:author
pubmed:issnType
Print
pubmed:volume
12
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
343-50
pubmed:dateRevised
2010-11-18
pubmed:meshHeading
pubmed:year
2000
pubmed:articleTitle
Sex-steroid induction of endogenous opioid inhibition on oxytocin secretory responses to stress.
pubmed:affiliation
Laboratory of Neuroendocrinology, Department of Biomedical Sciences, University of Edinburgh, Medical School, Edinburgh, UK. alison.j.douglas@ed.ac.uk
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't