Reduction of insulin binding in the arcuate nucleus of the rat hypothalamus after 6-hydroxydopamine treatment

Barbara J. Wilcox, Alvin M. Matsumoto, Daniel Dorsa, Denis G. Baskin

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

Insulin receptors are present in the hypothalamus, but the cell types bearing them are unknown. In order to test the hypothesis that some insulin receptors in the hypothalamus are associated with catecholamine terminals, rats were injected with 50 μg or 75 μg doses (intracerebroventricular) of 6-hydroxydopamine (6-OHDA). Control rats received vehicle only. The animals were sacrificed 7 days after injection, and catecholamine and indolamine levels in the hypothalamus were measured by high performance liquid chromatography with electrochemical detection. Localization of specific binding sites for [125I]-insulin in the arcuate (ARC), dorsomedial (DMN) and ventromedial (VMN) nuclei were determined by quantitative film autoradiography. Treatment with 6-OHDA resulted in a 70% reduction in hypothalamic norepinephrine content as compared to vehicle-treated controls (P <0.01). A slight depletion of epinephrine, dopamine and indolamines was also detected. Computerized image analysis of the autoradiograms was used to determine radioactivity bound (DPM/mm2) in each nucleus. Highest binding was in the ARC and DMN, with much lower binding in the VMN. Insulin binding in the ARC of the 6-OHDA-treated group was decreased by 25% compared to controls (P <0.01). No significant change in insulin binding was observed in the DMN or VMN. The 6-OHDA treatment had no significant effect on weight gain or on plasma insulin levels. The reduction of insulin binding in the ARC after 6-OHDA treatment supports the hypothesis that some insulin binding sites are located on catecholamine terminals in the arcuate nucleus.

Original languageEnglish (US)
Pages (from-to)149-155
Number of pages7
JournalBrain Research
Volume500
Issue number1-2
DOIs
StatePublished - Oct 23 1989
Externally publishedYes

Fingerprint

Arcuate Nucleus of Hypothalamus
Oxidopamine
Insulin
Hypothalamus
Catecholamines
Insulin Receptor
Therapeutics
Binding Sites
Autoradiography
Radioactivity
Epinephrine
Weight Gain
Dopamine
Norepinephrine
High Pressure Liquid Chromatography
Injections

Keywords

  • 6-Hydroxydopamine
  • Arcuate nucleus
  • Brain
  • Catecholamine
  • Insulin receptor
  • Quantitative autoradiography

ASJC Scopus subject areas

  • Developmental Biology
  • Molecular Biology
  • Clinical Neurology
  • Neuroscience(all)

Cite this

Reduction of insulin binding in the arcuate nucleus of the rat hypothalamus after 6-hydroxydopamine treatment. / Wilcox, Barbara J.; Matsumoto, Alvin M.; Dorsa, Daniel; Baskin, Denis G.

In: Brain Research, Vol. 500, No. 1-2, 23.10.1989, p. 149-155.

Research output: Contribution to journalArticle

Wilcox, Barbara J. ; Matsumoto, Alvin M. ; Dorsa, Daniel ; Baskin, Denis G. / Reduction of insulin binding in the arcuate nucleus of the rat hypothalamus after 6-hydroxydopamine treatment. In: Brain Research. 1989 ; Vol. 500, No. 1-2. pp. 149-155.
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AB - Insulin receptors are present in the hypothalamus, but the cell types bearing them are unknown. In order to test the hypothesis that some insulin receptors in the hypothalamus are associated with catecholamine terminals, rats were injected with 50 μg or 75 μg doses (intracerebroventricular) of 6-hydroxydopamine (6-OHDA). Control rats received vehicle only. The animals were sacrificed 7 days after injection, and catecholamine and indolamine levels in the hypothalamus were measured by high performance liquid chromatography with electrochemical detection. Localization of specific binding sites for [125I]-insulin in the arcuate (ARC), dorsomedial (DMN) and ventromedial (VMN) nuclei were determined by quantitative film autoradiography. Treatment with 6-OHDA resulted in a 70% reduction in hypothalamic norepinephrine content as compared to vehicle-treated controls (P <0.01). A slight depletion of epinephrine, dopamine and indolamines was also detected. Computerized image analysis of the autoradiograms was used to determine radioactivity bound (DPM/mm2) in each nucleus. Highest binding was in the ARC and DMN, with much lower binding in the VMN. Insulin binding in the ARC of the 6-OHDA-treated group was decreased by 25% compared to controls (P <0.01). No significant change in insulin binding was observed in the DMN or VMN. The 6-OHDA treatment had no significant effect on weight gain or on plasma insulin levels. The reduction of insulin binding in the ARC after 6-OHDA treatment supports the hypothesis that some insulin binding sites are located on catecholamine terminals in the arcuate nucleus.

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