The metabolic changes caused by dexamethasone in the adjuvant-induced arthritic rat |
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Authors: | Silvana M Caparroz-Assef Ciomar A Bersani-Amado Ana M Kelmer-Bracht Adelar Bracht Emy L Ishii-Iwamoto |
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Institution: | (1) Laboratory of Liver Metabolism, Department of Biochemistry, University of Maringá, 87020900 Maringá, Brazil |
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Abstract: | The action of orally administered dexamethasone (0.2 mg kg−1 day−1) on metabolic parameters of adjuvant-induced arthritic rats was investigated. The body weight gain and the progression of
the disease were also monitored. Dexamethasone was very effective in suppressing the Freund’s adjuvant-induced paw edema and
the appearance of secondary lesions. In contrast, the body weight loss of dexamethasone-treated arthritic rats was more accentuated
than that of untreated arthritic or normal rats treated with dexamethasone, indicating additive harmful effects. The perfused
livers from dexamethasone-treated arthritic rats presented high content of glycogen in both fed and fasted conditions, as
indicated by the higher rates of glucose release in the absence of exogenous substrate. The metabolization of exogenous l-alanine was increased in livers from dexamethasone-treated arthritic rats in comparison with untreated arthritic rats, but
there was a diversion of carbon flux from glucose to l-lactate and pyruvate. Plasmatic levels of insulin and glucose were significantly higher in arthritic rats following dexamethasone
administration. Most of these changes were also found in livers from normal rats treated with dexamethasone. The observed
changes in l-alanine metabolism and glycogen synthesis indicate that insulin was the dominant hormone in the regulation of the liver glucose
metabolism even in the fasting condition. The prevalence of the metabolic effects of dexamethasone over those ones induced
by the arthritis disease suggests that dexamethasone administration was able to suppress the mechanisms implicated in the
development of the arthritis-induced hepatic metabolic changes. It seems thus plausible to assume that those factors responsible
for the inflammatory responses in the paws and for the secondary lesions may be also implicated in the liver metabolic changes,
but not in the body weight loss of arthritic rats. |
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Keywords: | Dexamethasone Arthritis Perfused rat liver Gluconeogenesis l-Alanine metabolism" target="_blank">l-Alanine metabolism |
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