459-P: Liver-Targeted Mitochondrial Uncoupling by CRMP Improves Whole-Body Insulin Sensitivity and Attenuates Atherosclerosis in A LDLR-/- Mouse Model of Metabolic Syndrome

A unique mouse model was developed with elevated endogenous GH (2- to 3-fold) and IGF-I (1.2- to 1.4-fold), due to somatotrope-specific Cre-mediated inactivation of IGF-I receptor (IgfIr) and insulin receptor (Insr) genes (IgfIr,InsrrGHpCre, referred to as HiGH mice). We demonstrate that the metabolic phenotype of HiGH mice is diet dependent and differs from that observed in other mouse models of GH excess due to ectopic heterologous transgene expression or pituitary tumor formation. Elevated endogenous GH promotes lean mass and whole-body lipid oxidation but has minimal effects on adiposity, even in response to diet-induced obesity. When caloric intake is moderated, elevated GH improves glucose clearance, despite low/normal insulin sensitivity, which may be explained in part by enhanced IGF-I and insulin output. However, when caloric intake is in excess, elevated GH promotes hepatic lipid accumulation, insulin resistance, hyperglycemia, and ketosis. The HiGH mouse model represents a useful tool to study the role endogenous circulating GH levels play in regulating health and disease.

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Antisense oligonucleotides against the lipid phosphatase SHIP2 improve muscle insulin sensitivity in a dietary rat model of the metabolic syndrome

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.00263.2006 ◽

2007 ◽

Vol 292 (6) ◽

pp. E1871-E1878 ◽

Cited By ~ 15

Author(s):

Roland Buettner ◽

Iris Ottinger ◽

Christiane Gerhardt-Salbert ◽

Christian E. Wrede ◽

Jürgen Schölmerich ◽

...

Keyword(s):

Metabolic Syndrome ◽

Insulin Sensitivity ◽

Protein Content ◽

Insulin Action ◽

Whole Body ◽

Glucose Disposal ◽

Standard Diet ◽

The Metabolic Syndrome ◽

Lipid Phosphatase

The lipid phosphatase SH2 domain-containing lipid phosphatase (SHIP2) has been implicated in the regulation of insulin sensitivity, but its role in the therapy of insulin-resistant states remains to be defined. Here, we examined the effects of an antisense oligonucleotide (AS) therapy directed against SHIP2 on whole body insulin sensitivity and insulin action in liver and muscle tissue in a dietary rodent model of the metabolic syndrome, the high-fat-fed (HF) rat. Whole body insulin sensitivity was examined in vivo by insulin tolerance tests before and after the intraperitoneal application of an AS directed against SHIP2 (HF-SHIP2-AS) or a control AS (HF-Con-AS) in HF rats. Insulin action in liver and muscle was assayed by measuring the activation of protein kinase B (Akt) and insulin receptor substrate (IRS)-1/2 after a portal venous insulin bolus. SHIP2 mRNA and protein content were quantified in these tissues by real-time PCR and immunoblotting, respectively. In HF-SHIP2-AS, whole body glucose disposal after an insulin bolus was markedly elevated compared with HF-Con-AS. In liver, insulin activated Akt similarly in both groups. In muscle, insulin did not clearly activate Akt in HF-Con-AS animals, whereas insulin-induced Akt phosphorylation was sustained in SHIP2-AS-treated rats. IRS-1/2 activation did not differ between the experimental groups. SHIP2 mRNA and protein content were markedly reduced only in muscle. In standard diet-fed controls, SHIP2-AS reduced SHIP2 protein levels in liver and muscle, but it had no significant effect on insulin sensitivity. We conclude that treatment with SHIP2-AS can rapidly improve muscle insulin sensitivity in dietary insulin resistance. The long-term feasability of such a strategy should be examined further.

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