抄録
Previous studies reported that cobalt chloride (CoCl2) caused the reduction of serum glucose concentration in streptozotocin (STZ)-induced diabetic rats. The reduction should be resulted from the decreases in systemic glucose production and/or the increases in cellular glucose uptake. Furthermore, CoCl2 has been known to stimulate expressions of glucose transporters. Here, we hypothesized that the increases in glucose uptake due to the enhancement of the expression would lead to increase glycogen contents, and determined glycogen contents in the rat muscle and liver where glycogen is mainly stored. The serum insulin concentrations at 3 weeks after the injection of STZ were depleted, accompanied with the increases in serum glucose from 65.9 ± 9.8 to 410 ± 45.7 mg/dl (P<0.01). The liver glycogen contents decreased from 46.5 ± 27.7 to 1.5 ± 0.9 mg/g tissue (P<0.01). However, STZ had no effects on muscle glycogen contents. When the rats were treated with 2 mM CoCl2, the serum glucose concentrations decreased to 338 ± 24.1 mg/dl (P<0.05). The serum insulin concentrations remained the depletion. No changes in the muscle glycogen contents were observed. In contrast, the liver glycogen contents significantly increased to 29.1 ± 18.1 mg/g tissue (P<0.01). These data suggest that the serum glucose-lowering effect of CoCl2 on the STZ-diabetic rats is mediated by increase of liver glycogen content. [Jpn J Physiol 54 Suppl:S234 (2004)]
