抄録
We investigated the effects of estrogen on insulin signaling in ovariectomized (OVX) rats. Female Wistar rats aged 9 wks were divided randomly into three groups: sham operated (S) group, OVX plus placebo-treated (P) group, and OVX plus estrogen-treated (E) group. The rats in the P or the E group were subcutaneously implanted with placebo or 17β-estradiol (1.5 mg/60-day release) pellets 4 wks after ovariectomy. The experiment was performed 4 wks after the replacement. After 16 hr fasting, the rats were injected with a normal saline with or without 10−5 M insulin from their portal veins. The liver and the hindlimb skeletal muscle were removed 30 s and 90 s later, respectively. These samples were analyzed for PI3-kinase activity and Akt phosphorylation. In the muscle, insulin-stimulated PI3-kinase activity associated with insulin receptor substrate (IRS)-1 was significantly increased in the E group, but not in the P group. In the liver, insulin-stimulated elevation in IRS-1 related PI3-kinase activity was not observed in either P or E group. There were no significant differences in the amount of IRS-1 and Akt between the three groups. These results suggest that estrogen replacement in OVX rats increases insulin-stimulated PI3-kinase activity associated with IRS-1 in the hindlimb muscle. [J Physiol Sci. 2007;57 Suppl:S185]
