Document Detail


Changes in the expression of the nerve growth factor receptors TrkA and p75LNGR in the rat thymus with ageing and increased nerve growth factor plasma levels.
MedLine Citation:
PMID:  10955718     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The nerve growth factor (NGF) receptors p75LNGR and TrkA are expressed by thymic epithelial cells. Presumably, the NGF-TrkA system is involved in the paracrine communication between thymic epithelial cells and thymocytes, whereas the functional role of p75LNGR is still unknown. The thymus of vertebrates undergoes age-related changes that in part depend on hormonal factors. In order to find out whether thymic epithelial cells are responsive to NGF during the whole lifespan of the rat, we studied NGF receptor expression in the thymus from birth to 2 years of age, using immunohistochemistry. Furthermore, to evaluate whether increased plasma levels of NGF affected the ageing process, either NGF or 4-methylcatechol (4MC), an inductor of NGF synthesis, was administered. Both TrkA and p75LNGR were expressed by a subpopulation of thymic epithelial cells during the whole age range studied and their expression peaked at around 3 months. TrkA was primarily found in subcortical and medullary epithelial cells, whereas p75LNGR was seen in a subpopulation of medullary cells. Cortical epithelial cells, neural crest-derived cells, other stromal cells and thymocytes were not immunoreactive for NGF receptors. Neither the administration of NGF nor the increased NGF plasma levels obtained after 4MC treatment seemed to affect the ageing of the thymus as assessed by morphological and immunohistochemical criteria, but this increase in NGF levels did produce a shift in the expression of p75LNGR from epithelial cells to ED1-positive macrophages in animals of 6 months and older. Present results indicate that the expression of p75LNGR and TrkA in the rat thymus undergoes age-dependent changes that parallel those of epithelial cells. NGF could therefore be important for thymus homeostasis, possibly acting on epithelial cells. Nevertheless, NGF did not seem to be able to prevent the involution of this organ, although it produced a switch in the expression of p75LNGR, the significance of which remains to be established.
Authors:
O García-Suárez; A Germanà; J Hannestad; M Pérez-Pérez; I Esteban; F J Naves; J A Vega
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Cell and tissue research     Volume:  301     ISSN:  0302-766X     ISO Abbreviation:  Cell Tissue Res.     Publication Date:  2000 Aug 
Date Detail:
Created Date:  2000-11-21     Completed Date:  2001-02-01     Revised Date:  2009-11-19    
Medline Journal Info:
Nlm Unique ID:  0417625     Medline TA:  Cell Tissue Res     Country:  GERMANY    
Other Details:
Languages:  eng     Pagination:  225-34     Citation Subset:  IM    
Affiliation:
Departmento de Morfología y Biología Celular, Facultad de Medicina, Universidad de Oviedo, Spain.
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MeSH Terms
Descriptor/Qualifier:
Aging*
Animals
Catechols / pharmacology
Epithelial Cells / metabolism
Immunohistochemistry
Macrophages / metabolism
Male
Nerve Growth Factor / blood*,  pharmacology
Rats
Rats, Wistar
Receptor, Nerve Growth Factor / immunology,  metabolism*
Receptor, trkA / immunology,  metabolism*
Thymus Gland / cytology,  growth & development*,  metabolism*
Chemical
Reg. No./Substance:
0/Catechols; 0/Receptor, Nerve Growth Factor; 452-86-8/4-methylcatechol; 9061-61-4/Nerve Growth Factor; EC 2.7.10.1/Receptor, trkA

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