Divergent effects of insulin on insulin-like growth factor-II gene expression in the rat hypothalamus

Thomas J. Lauterio, Paul F. Aravich, Peter Rotwein

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Abstract

The effect of peripheral insulin treatment on brain content and synthesis of insulin-like growth factor-II (IGF-II) was studied in acute and chronic conditions. After a 3-h hyperinsulinemic/euglycemic clamp, rats were killed, and brains were removed for IGF-II analysis. Insulin infusion elevated IGF-II concentrations in the dorsomedial hypothalamus (DMH) and suprachiasmatic nucleus, but decreased IGF-II in the paraventricular nucleus, lateral hypothalamus (LtH), and supraoptic nucleus compared to values in control animals. In separate parallel studies, the effects of 4 days of insulin injection (1 U insulin/rat, sc, twice daily) on brain IGF-II mRNA and peptide were determined. For RNA analysis the hypothalamus was divided into three regions (lateral, ventral, and dorsal). IGF-II mRNA content was shown to vary by an order of magnitude within the adult rat hypothalamus under control conditions, and there appeared to be a differential region-dependent response to insulin treatment. Relative abundance of IGF-II mRNA in control hypothalami was VH ≫ cortex ≥ LtH > DMH. IGF-II mRNA content declined after insulin treatment in the VH, but rose in all other regions. Insulin increased IGF-II peptide content in the paraventricular nucleus, LtH, and VMH but decreased IGF-II in the DMH and suprachiasmatic nucleus. These results indicate that peripheral insulin status may be an important factor in the synthesis and secretion of IGF-II in the brain.

Original languageEnglish (US)
Pages (from-to)392-398
Number of pages7
JournalEndocrinology
Volume126
Issue number1
Publication statusPublished - Jan 1990
Externally publishedYes

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ASJC Scopus subject areas

  • Endocrinology
  • Endocrinology, Diabetes and Metabolism

Cite this

Lauterio, T. J., Aravich, P. F., & Rotwein, P. (1990). Divergent effects of insulin on insulin-like growth factor-II gene expression in the rat hypothalamus. Endocrinology, 126(1), 392-398.