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Abstract
Chromatin supraorganization and extensibility and nuclear glycoprotein content have
been reported to change in hepatocytes from mice during development and aging, as
well as under starvation and refeeding conditions. In non-obese diabetic (NOD) mice,
the expression of insulin-dependent diabetes may be accompanied by metabolic changes
in the liver. These changes are likely to be similar to those involved in the aging
processes of non-diabetic animals. Therefore, we hypothesized that the chromatin organization,
as well as the physical properties and compositions of hepatocyte nuclei would also
be affected in NOD mice in the same way as those in aged non-diabetic mice. Nuclear
image parameters were evaluated by image analysis of Feulgen-stained preparations.
Chromatin extensibility in response to gravity was observed with polarized light after
lysis and toluidine blue staining. The Con-A response of nuclear glycoproteins was
evaluated with scanning microspectrophotometry. These characteristics were assessed
using hepatocyte imprints from female NOD mice after a 28-day period of diabetes expression.
Observations and measurements were made in comparison to healthy BALB/c mice. Total
RNA amounts were determined for livers of NOD and BALB/c mice. Enhanced polyploidy
levels, a decrease in chromatin higher-order packing states, an increased frequency
of extended chromatin fiber formation, and deeper Con-A-responsive chromatin areas
were observed in the hepatocytes of the NOD mice expressing insulin-dependent diabetes.
Reduced amounts of total RNA were also found in the livers of these mice. Our findings
for NOD mice expressing insulin-dependent diabetes are consistent with previously
reported data for old-aged mice of the inbred strain A/Uni and may reflect changes
in transcriptional activities associated with the stressful physiological demands
on the liver during the expression of diabetes.