Hormonal Regulation of the Glycogen/Glucose Balance in Xenopus laevis

Abstract

BackgroundThe South African clawed toad Xenopus laevis (Daudin) was used to study the hormonal regulation of glycogen metabolism in amphibians. Preliminary investigations had shown that the liver glycogen in this animal is not only very high but also very stable under physiologic conditions. It was the aim of this study to analyze systematically the effects of hormones and various substances relevant to the glycogen/glucose balance in the adult males and females. [1]

Tissue‐specific selenium accumulation and toxicity in adult female Xenopus laevis chronically exposed to elevated dietary selenomethionine

“…The marginal decrease observed in liver glycogen concentrations of the SeMet-treated females could be because of slightly higher metabolic costs related to exposure even though they were still within the normal range of literature values. Typically, under nonbreeding conditions, X. laevis females have markedly high levels of glycogen content in the liver (15% of liver wet mass) [45,46]. However, rapid depletion of liver glycogen concentrations does occur under breeding conditions where X. laevis liver glycogen content dramatically decreases to approximately 5% of the liver wet mass [46].…”

“…Typically, under nonbreeding conditions, X. laevis females have markedly high levels of glycogen content in the liver (15% of liver wet mass) [45,46]. However, rapid depletion of liver glycogen concentrations does occur under breeding conditions where X. laevis liver glycogen content dramatically decreases to approximately 5% of the liver wet mass [46]. The average percentage of glycogen present in the whole liver of X. laevis females in the present study ranged from 6.1% to 8.4%, which is similar to values reported previously in X. laevis after administration of human chorionic gonadotropin or after vitellogenesis has transpired [45,46].…”

“…However, rapid depletion of liver glycogen concentrations does occur under breeding conditions where X. laevis liver glycogen content dramatically decreases to approximately 5% of the liver wet mass [46]. The average percentage of glycogen present in the whole liver of X. laevis females in the present study ranged from 6.1% to 8.4%, which is similar to values reported previously in X. laevis after administration of human chorionic gonadotropin or after vitellogenesis has transpired [45,46]. Although excess dietary Se is linked to greater concentrations of both triglyceride and glycogen in several fish species [17,20,37,38], decreases in glycogen in combination with no change to triglyceride or cortisol concentrations of resting juvenile fathead minnows fed 9.9 mg Se/g and 26.5 mg Se/g dry mass have been reported [18], thus demonstrating that age, dietary Se concentration, and species sensitivity play vital roles in how energy stores are regulated in relation to exposure.…”