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2-adrenergic receptor gene in
rat liver during sepsis
Department of Pharmacological and Physiological Science, St. Louis University School of Medicine, St. Louis, Missouri 63104
Changes in
2-adrenergic receptor
(
2-AR) gene expression in the
rat liver during different phases of sepsis were studied. Sepsis was
induced by cecal ligation and puncture (CLP). Septic rats exhibit two
metabolically distinct phases: an initial hyperglycemic (9 h after CLP;
early sepsis) followed by a hypoglycemic phase (18 h after CLP; late
sepsis). The
[3H]dihydroalprenolol
binding studies show that the density of
2-AR was decreased by 12 and
35% during the early and late phases of sepsis, respectively. Western
blot analyses depict that the
2-AR protein level was reduced
by 37 and 72% during early and late sepsis, respectively. The reverse
transcription polymerase chain reaction and Southern blot analyses
reveal that the steady-state level of
2-AR mRNA was decreased by 37%
during early phase and 77% during late phase of sepsis. Nuclear
run-off assays show that the rate of transcription of
2-AR mRNA was reduced by 36%
during early sepsis and 64% during late sepsis. The stability assays indicate that the half-life of
2-AR mRNA was shortened by 21 and 50% during the early and late phases of sepsis, respectively, indicating that the rate of degradation of
2-AR mRNA was progressively enhanced during sepsis. These findings demonstrate that the
2-AR gene was underexpressed in
the liver during the progression of sepsis, and, furthermore, the
underexpression of the
2-AR
gene was the result of a reduction in the rate of transcription coupled with an enhancement in the rate of degradation of
2-AR gene transcripts. Thus our
findings that the transcriptional and posttranscriptional regulation of
2-AR gene associated with
decreases in
2-AR number and
its protein expression may provide a molecular mechanistic explanation
for the development of hypoglycemia during the late stage of sepsis.
septic shock; glucose dyshomeostasis; hepatic dysfunction
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