Publication: Morphological changes to somatotroph cells and in vitro individual GH release, in male rats treated with recombinant human GH
Loading...
Date
2000
Authors
Jiménez Reina, L. ; Cañete, R. ; Cepeda, T. ; Bernal, G.
item.page.secondaryauthor
item.page.director
Publisher
Murcia : F. Hernández
publication.page.editor
publication.page.department
DOI
item.page.type
info:eu-repo/semantics/article
Description
Abstract
The effect of in vivo chronic administration
of recombinant human growth hormone (rhGH) on
morphology and individual GH release in somatotroph
cells was evaluated in young male Wistar rats. Over an
18-day period, 30-day-old male rats were injected daily
with 1.5 1U rhGH/kg (GPG group) or saline (VPG
group) by subcutaneous injection. Electron-immunocytochemical,
ultrastructural and morphometric studies
of somatotroph cells were carried out. Additionally, rat
pituitary cells were dispersed and overall and individual
GH release was studied by radioimmunoassay and cell
immunoblot assay (quantified by image analysis),
respectively. The ultrastructure and size of somatotroph
cells did not change, but volume density of secretion
granules was reduced (pc0.01) by previous in vivo GH
treatment. At four days, basal GH release of rat pituitary
cell monolayer cultures was lower in the GPG group
than in the VPG group (pc0.05); after 12 hours of
culture, GHRH stimulation of GH release was lower in
the GPG group than in the VPG group (p<0.05), and
GHRH+SRIH inhibited GH release in the GPG group
(p<0.05), but not in the VPG group. The percentage of
somatotroph cells was not modified, but the ratio of
strongly/weakly GH-immunostained cells had changed;
weakly GH-immunostained cells increased from 34% to
55%. Moreover, in vitro treatment with GHRH, SRIH,
and both, easily changed the strongly/weakly GHimmunostained
cell ratio. Individual GH release,
however, was not changed by previous in vivo GH
treatment, although GHRH preferably stimulated a
subpopulation of GH cells and SRIH did not inhibit
individual GH release. These data suggest that
exogenous chronic rhGH treatment down-regulates
somatotroph function by modifying the proportion of
GH cell subpopulation.
publication.page.subject
Citation
item.page.embargo
Ir a Estadísticas
Sin licencia Creative Commons.