Alcohol-Induced Increases in Insulin-Like Growth Factor Binding Protein-1 Are Partially Mediated by TNF

Authors

  • Vinayshree Kumar,

    1. Departments of Cellular and Molecular Physiology, and Surgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
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  • Christine Silvis,

    1. Departments of Cellular and Molecular Physiology, and Surgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
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  • Gerald Nystrom,

    1. Departments of Cellular and Molecular Physiology, and Surgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
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  • Nobuko Deshpande,

    1. Departments of Cellular and Molecular Physiology, and Surgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
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  • Thomas C. Vary,

    1. Departments of Cellular and Molecular Physiology, and Surgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
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  • Robert A. Frost,

    1. Departments of Cellular and Molecular Physiology, and Surgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
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  • Charles H. Lang

    Corresponding author
    1. Departments of Cellular and Molecular Physiology, and Surgery, Pennsylvania State University College of Medicine, Hershey, Pennsylvania.
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  • April 18, 2002;

  • July 30,2002.

  • This work was supported by National Institutes of Health grant AA11290 (CHL) and AA12814 (TCV).

Charles H. Lang, PhD, Penn State College of Medicine, Department of Cellular and Molecular Physiology (H166), Hershey, PA 17033; Fax: 717–531–7667; E-mail: clang@psu.edu

Abstract

Background Alcohol (EtOH) alters the plasma and tissue content of insulin-like growth factor (IGF)-I, an important anabolic hormone. However, the bioavailability and bioactivity of IGF-I can also be modulated by changes in soluble proteins that bind IGF-I (IGFBPs). The purpose of the present study was to determine whether EtOH intoxication in rats alters the plasma concentration and tissue mRNA content of various IGFBPs. Based on initial results subsequent studies were performed to assess potential mechanisms by which EtOH increased IGFBP-1.

Methods Rats were administered EtOH (75 mmol/kg) and blood and tissues collected at various times thereafter. Separate groups of rats were also pretreated with 4-methylpyrazole (4-MP; alcohol dehydrogenase inhibitor), cyanamide (inhibitor of acetaldehyde metabolism), RU486 (glucocorticoid receptor antagonist) or the tumor necrosis factor (TNF) antagonist (TNFBP) prior to EtOH administration.

Results Acute EtOH intoxication did not alter the mRNA content of IGFBP-3, -4 or -5 in liver or kidney. However, EtOH increased IGFBP-1 in blood (5-fold), which was associated with an up-regulation of IGFBP-1 mRNA content in liver and kidney (2- to 3-fold). Likewise, the injection of the nonmetabolizable alcohol tert-butanol also increased IGFBP-1 in plasma, liver, and kidney. The increased IGFBP-1 in blood and tissues was not prevented by inhibiting alcohol metabolism with 4-MP. However, pretreatment with cyanamide markedly accentuated the EtOH-induced increase in IGFBP-1 in blood (20-fold), liver (3.5-fold), and kidney (12-fold), indicating that accumulation of acetaldehyde can enhance IGFBP-1 synthesis. A time course study indicated that EtOH increased plasma IGFBP-1 levels as early as 0.5–1 hr, and that this response was associated with elevated IGFBP-1 mRNA in liver but not kidney. Pretreatment with RU486 did not prevent or attenuate the EtOH-induced increase in IGFBP-1. However, the alcohol-induced increase in IGFBP-1 was attenuated by TNFBP.

Conclusions These data suggest that the acute alcohol-induced increase in IGFBP-1 is mediated, at least in part, by TNF and is independent of EtOH metabolism and increases in endogenous glucocorticoids.

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