Possible Interaction: Glucosamine and Insulin

“Additional in vitro experimental support for the glucosamine hypothesis comes from findings indicating that GlcN induces insulin resistance in isolated rat muscle (23) and may modulate insulin’s and/or glucose’s effects on pyruvate kinase (24), glycogen synthase (23, 25) and transforming growth factor-a (26).”

“ GlcN infusion has also been reported to influence insulin sensitivity not only in skeletal muscle and adipose tissue but also in heart muscle and liver (31).”

“An overnight exposure to glucosamine markedly attenuated the effects of insulin and IGF-I in stimulating glycogen synthesis.”

“Exposure to glucosamine also resulted in a reduction in the ability of IGF-I or insulin to stimulate phosphorylation of insulin IGF-I/HRs.”

“Taken together, … indicate that glucosamine induces a loss … to stimulation of insulin , IGF-I, or HR tyrosine kinase activity by insulin or IGF-I. Although insulin is able to partially reverse … of glucosamine on IR phosphorylation, it has a very minimal effect on glucosamine-induced inhibition of HR phosphorylation.”

“The combination of insulin plus IGF-I was a more potent stimulus of HR phosphorylation than either agent alone, and this combination was also more potent in partially reversing the inhibitory effect of glucosamine.”

“ Insulin hastened the disappearance of glucosamine from the plasma of the alligator.”

“Overall, the findings support a model whereby GAM promotes ER stress in retinal Müller cells, resulting in elevated REDD1 expression and thus resistance to insulin action.”

“For instance, whereas in one study, short-term glucosamine did not influence insulin sensitivity in humans, another study demonstrated that long-term glucosamine treatment does attenuate insulin release.”

“…,insulin stimulated-glucose transport was significantly increased and continued to increase up to 6-24 h. Insulin stimulation of Akt, however, did not increase after … increase after 6 h. Next, we investigated effects of osmotic shock and vanadate on glucose transport in glucosamine-treated cells and found that glucosamine ….”

“When we measured the kinase activity of protein kinase C (PKC) lamda, which is the downstream effector of PI 3-kinase in isolated adipocytes, we found that glucosamine inhibited insulin stimulated PKClamda kinase activity by 33%.”

“However, only preincubation with GlcN plus insulin inhibited insulin-stimulated GLUT4 translocation.”

“ GlcN inhibits insulin action on both PKA and CK-1 activities.”

“Surprisingly, glycogen synthase activation by insulin was enhanced 4-fold, in part due to allosteric activation by a glucosamine metabolite.”