Linked Life Data

8735604

Source:http://linkedlifedata.com/resource/pubmed/id/8735604

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1-2
pubmed:dateCreated
1996-11-19
pubmed:abstractText
Mammalian aging is characterized by a decline in the content and release of pituitary growth hormone (GH). However, few studies on the age-related changes in the population of GH-producing cells (somatotropes) have been carried out. We have investigated whether changes in number, ultrastructure and GH gene expression in subpopulations of somatotropes could explain the reduced GH release in aged rats. Three representative ages were studied: adult (5-month-old), old (19-month-old), and senescent (26-month-old) male rats. The total number of immunoreactive-GH cells per pituitary gland remained invariable to age. The separation of dispersed pituitary cells on a density gradient yielded two somatotrope subpopulations, of low density (LD) and high density (HD). Both subpopulations were equally represented in adults, whereas in old and senescent rats a predominance of LD-somatotropes was observed. Morphometric analysis showed that subpopulations exhibited storage and biosynthetic features inversely related. In LD-somatotropes, rough endoplasmic reticulum (RER) was more prominent but secretory granules (SG) were less abundant than in HD somatotropes. Concurrently, in situ hybridization for GH mRNA showed that GH gene expression was higher in LD-cells. Differences between subpopulations were essentially retained through the animals' lifespan, but small-sized SG, reduced RER, and low GH mRNA levels were inherent to aging both in LD- and in HD-somatotropes. The present findings demonstrate that the reduced content of pituitary GH in aged male rats is not due to a diminished number of GH-producing cells, but to the numerical predominance of scarcely granulated LD-somatotropes, combined with the decline in GH biosynthetic capacity observed in both subpopulations. In addition, age-related changes in ultrastructure and GH gene expression suggest a chronic inhibition of GH release and/or a weak stimulation of GH biosynthesis affecting both subpopulations.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Apr
pubmed:issn
0303-7207
pubmed:author
pubmed:issnType
Print
pubmed:day
19
pubmed:volume
118
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
181-91
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Heterogeneity of growth hormone (GH)-producing cells in aging male rats: ultrastructure and GH gene expression in somatotrope subpopulations.
pubmed:affiliation
Department of Cell Biology, Faculty of Sciences, University of Córdoba, Spain.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't