Dm. Hall et al., Aging lowers steady-state antioxidant enzyme and stress protein expressionin primary hepatocytes, J GERONT A, 56(6), 2001, pp. B259-B267
Citations number
38
Categorie Soggetti
Public Health & Health Care Science","Medical Research General Topics
Journal title
JOURNALS OF GERONTOLOGY SERIES A-BIOLOGICAL SCIENCES AND MEDICAL SCIENCES
It has been reported that the isolation and culture of primary hepatocytes
can compromise cellular ability to constituitively express antioxidant enzy
me (AE) genes, making it difficult to study their regulation ex vivo. In th
e present study, the steady-state expression of manganese-containing supero
xide dismutase, copper- and zinc-containing superoxide dismutase, catalase,
and glutathione peroxidase was assessed in primary hepatocytes isolated fr
om young and senescent rats and cultured in Matrigel. There was no change i
n steady-state superoxide dismutase protein or activity levels in cells col
lected from young animals and cultured for 7 days. Catalase expression was
initially increased, and then it declined 30%. In contrast, superoxide dism
utase expression declined 60% and catalase expression declined 50% in cells
from senescent animals. Constitutive and inducible 70-kDa heat shock prote
in expression increased coincident with declining AE levels in the young ce
lls but not senescent cells. For both age groups, electron micrographs show
ed rounded hepatocytes with abundant rough endoplasmic reticulum, mitochond
ria, and peroxisomes. Hepatocytes were organized into clusters of 6-12 cell
s surrounding a large central lumen devoid of microvilli. Each cluster also
contained smaller microvilli-lined lumens between adjacent hepatocytes tha
t resembled canniculi. The plasma membranes of these lumens were sealed fro
m the extracellular space by junctional complexes. Gap junctions in the pla
sma membrane suggest that hepatocytes were capable of intercellular communi
cation. We conclude that the Matrigel system can be used to study AE regula
tion in primary hepatocytes from young and senescent animals, provided that
experiments can be conducted within a time frame of 5-7 days in culture. T
hese data also support the hypothesis that aging compromises hepatocellular
ability to maintain AE status and upregulate stress protein expression.