Linked Life Data

2963973

Source:http://linkedlifedata.com/resource/pubmed/id/2963973

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1988-4-5
pubmed:abstractText
Syrian hamsters kept in long day-lengths have active gonads and high circulating levels of gonadal steroids. Under the influence of the pineal gland, animals exposed to short photoperiods undergo testicular regression, have low circulating levels of testosterone and gonadotrophins and elevated levels of beta-endorphin within the hypothalamus. This paper describes the interaction between testosterone and photoperiod in the regulation of beta-endorphin levels in three regions of the hypothalamus. Hypothalamic beta-endorphin levels were measured by a combination of high-performance liquid chromatography and radioimmunoassay techniques that allows separation of the beta-endorphin (1-31) peptide from its metabolites and precursors. All of the beta-endorphin-like immunoreactivity in the hypothalamus of the male hamster, in both photoinhibited and photostimulated conditions, was found to represent the 31-amino-acid peptide. In photostimulated hamsters, chronic castration was associated with a significant increase of beta-endorphin levels in the anterior hypothalamus and mediobasal hypothalamus, which was reversed by treatment with exogenous testosterone. Castration prevented the ability of naloxone, an opiate receptor antagonist, to release luteinizing hormone, and this effect was also reversed by exogenous steroid. In photoinhibited hamsters, however, castration had no effect upon beta-endorphin levels in the preoptic area or mediobasal hypothalamus, and there was only a small increment in the anterior hypothalamus. Significantly, beta-endorphin levels in all areas of the hypothalamus of photoinhibited castrates were not decreased by testosterone treatment. In addition, administration of exogenous testosterone did not restore sensitivity to naloxone in these animals.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Dec
pubmed:issn
0306-4522
pubmed:author
pubmed:issnType
Print
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1075-82
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1987
pubmed:articleTitle
The effects of castration, testosterone replacement and photoperiod upon hypothalamic beta-endorphin levels in the male Syrian hamster.
pubmed:affiliation
University of Cambridge, Department of Anatomy, U.K.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't