This subproject is one of many research subprojects utilizing theresources provided by a Center grant funded by NIH/NCRR. The subproject andinvestigator (PI) may have received primary funding from another NIH source,and thus could be represented in other CRISP entries. The institution listed isfor the Center, which is not necessarily the institution for the investigator.Fibrates, activators of the nuclear receptor PPAR, improve dyslipidemia but their effects on insulin resistance and vascular disease are unresolved. To test the hypothesis that PPAR activation improves insulin resistance and vascular function, we determined the effects of fenofibrate in healthy adults with insulin resistance induced by short-term glucocorticoid administration. Eighteen normal weight subjects were studied in 4 stages: at baseline, after 21 days of fenofibrate (160 mg/day) alone, after 3 days of dexamethasone (8 mg/day) added to fenofibrate, and after 3 days of dexamethasone added to placebo (dexamethasone alone). Dexamethasone alone caused hyperinsulinemia, increased glucose, decreased glucose disposal and reduced insulin-induced suppression of hepatic glucose production as determined by hyperinsulinemic-euglycemic clamp, and increased systolic blood pressure as determined by ambulatory monitoring, features associated with an insulin resistant state. Fenofibrate improved fasting LDL and total cholesterol in the setting of dexamethasone treatment, but had no significant effect on levels of insulin or glucose, insulin-stimulated glucose disposal or insulin suppression of glucose production during clamps, or ambulatory-monitored blood pressure. In the absence of dexamethasone, fenofibrate lowered fasting triglycerides and cholesterol but unexpectedly increased systolic blood pressure by ambulatory monitoring. These data suggest that PPARactivation in humans does not diminish insulin resistance induced by glucocorticoids and may adversely affect blood pressure.
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