Glycogen synthesis in the perfused liver of streptozotocin-diabetic rats

Abstract

1. Net glycogen accumulation was measured in sequentially removed samples during perfusion of the liver of starved streptozotocin-diabetic rats, and shown to be significantly impaired, compared with rates in normal (starved) rats. 2. In perfusions of normal livers with glucose plus C3 substrates, there was an increase in the proportion of glycogen synthetase 'a', compared with that in the absence of substrates. This response to substrates, followed in sequential synthesis and enzymic sensitivity in the perfused liver of diabetic rats were reversed by pretreatment in vivo with glucose plus fructose, or insulin. Glucose alone did not produce this effect. 4. Glucose, fructose, insulin or cortisol added to e perfusion medium (in the absence of pretreatment in vivo) did not stimulate glycogen synthesis in diabetic rats. 5. In intact diabetic rats, there was a decline in rates of net hepatic glycogen accumulation, and the response of glycogen synthetase to substrates. The most rapid rates of synthesis were obtained after fructose administration. 6. These results demonstrate that there is a marked inherent impairment in hepatic glycogen synthesis in starved diabetic rats, which can be rapidly reversed in vivo but no in perfusion. Thus hepatic glycogen synthesis does not appear to be sensitive to either the short-term direct action of insulin (added alone to perfusions) of to long-term insulin deprivation in vivo. The regulatory roles of substrates, insulin and glycogen synthetase in hepatic glycogen accumulation are discussed.

Glutathione depletion induces glycogenolysis dependent ascorbate synthesis in isolated murine hepatocytes

“…First, fructose was administered to inhibit glycogen breakdown [28] and activate glycogenesis [29]. Addition of 4 mM fructose did not alter the GSH consumption caused by different agents but as expected it prevented their glycogenolytic effect and rather glycogen formation occurred (Table 2).…”

Synthesis and characterization of Solanum nigrum-mediated silver nanoparticles and its protective effect on alloxan-induced diabetic rats

“…Whereas, the treatment with plant extract as well as phytosynthesized AgNPs significantly improved the body weight loss. The TC and TG levels were retrieved comparable to normal group over a period of 21 days administration of AgNPs, the mechanism of preventing the muscle loss could probably attribute to reversal of antagonism [38].…”

Effect of Deoxynojirimycin on Glycogenesis in Liver of Mice, Mus norvegicus albinus

“…Glycogen is therefore useful for providing a readily available source of glucose for the body. Whitton and Hems (1975) observed a decrease in liver glycogen in rat perfused with STZ and impairments in glycogen synthesis. Gardner, et.al, (1993) suggested that regulation of glucose-6-phosphatse by insulin plays a role in the suppression of hepatic glucose production during feeding.…”