Evidence for chromium acting as an essential trace element in insulin-dependent glucose uptake in cultured mouse myotubes

Abstract

Previous work from this and other laboratories has suggested that the trace element chromium plays some role in glucose homeostasis. In this study, we sought to characterise an in vitro cell culture model in which the effects of chromium on insulin-dependent glucose uptake could be studied. Mouse C2C12 myoblasts were differentiated to form myotubes in culture in chromium-replete or chromium-poor media. Chromium levels in standard media were 0.56 +/- 0.01 micrograms/l (mean +/- S.E.M.) compared with 0.09 +/- 0.01 micrograms/l in chromium-poor media. In chromium-poor media, insulin-stimulated uptake of radiolabelled glucose was reduced by almost 50% compared with that found in chromium-replete media. This decreased response could be restored by the addition of physiologically relevant (0.3 micrograms/l) concentrations of inorganic chromium (P < 0.001). The sensitivity of these cells to insulin was reduced dramatically by a reduction in the chromium content of the medium and was again increased (P < 0.001) by chromium addition. The concentrations of chromium required to restore the sensitivity to insulin were of the same order as those found physiologically; much higher concentrations of chromium could also stimulate glucose uptake in the absence of insulin but such concentrations were supra-physiological.

Chromium picolinate positively influences the glucose transporter system via affecting cholesterol homeostasis in adipocytes cultured under hyperglycemic diabetic conditions

“…The relative enhancing effect of metformin was higher in cells incubated in 25 mM glucose rather than in 5 mM glucose, consistent with its selective action in hyperglycemic conditions in vivo [30,32]. As reported for metformin [33][34][35][36], the effects of CrPic are not attributed to increased expression of GLUT4 protein but rather its translocation and/or activation state [18,[37][38][39]. Combined, these results predict that during the hyperglycemic state Cr 3+ may functionally enhance insulin action by targeting the plasma membrane.…”

Effect of dietary chromium picolinate on growth performance and blood parameters in grass carp fingerling, Ctenopharyngodon idellus

“…The role of chromium in carbohydrate metabolism has been reported for both turkeys and humans (Levine et al 1968). It has been reported that organic chromium supplementation to diets of rats (Gray and Bowman 1992), mice (Morris et al 1995), chickens (Lien et al 1999) and feeder calves (Kegley and Spears 1995) had positive effects on glucose metabolism and insulin activity. Chromium has improved glucose tolerance in both experimental animals and man (Mertz 1969;Doisy et al 1976).…”

Increased chromium excretion in pregnancy is associated with insulin resistance

“…A growing number of studies from this and other laboratories [9][10][11] imply that chromium has a role to play in insulin action. We were able to clearly show with in vitro studies that a depletion of chromium significantly reduces the ability of insulin to stimulate glucose uptake: this sensitivity to insulin was restored when chromium concentrations were increased to "physiological" levels [12]. Does the increase in chromium excretion (and hence increased insulin resistance) result in an improved physiological response by some women to their pregnancy which ensures adequate supplies of glucose to the growing fetus?…”