Insulin receptors and insulin action in dissociated brain cells

Brian A. Masters, Joshua Shemer, Jennifer H. Judkins, Derrel W. Clarke, Derek Le Roith, Mohan K. Raizada*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

The present study was conducted to characterize insulin receptors and insulin action in rat brain cells. Binding of [125I]insulin to cells obtained by mechanicaly dissociating rat brains was 86% specific, time-dependent and reached equilibrium within 90 min. The t 1 2 of association was 14 min and t 1 2 of dissociation was 8 min. Scatchard analysis demonstrated the typical curvilinear plot providing high affinity (0.03 nM) and low affinity (6.6 nM) binding sites. The total number of binding sites were 0.15 pmol/mg protein. Crosslinking of [125I]insulin to its receptors on dissociated brain cells followed by SDS-PAGE and autoradiography showed that the α-subunit of the receptor had a molecular weight of 122,000. This was in contrast with a molecular weight of 134,000 for the liver α-subunit. Incubation of dissociated brain cells with insulin resulted in a concentration-dependent inhibition of total [3H]norepinephrine (NE) uptake. This inhibitory effect of insulin on [3H]NE uptake was soduim ino-dependent suggesting that 80-98% of the sodium ion-dependent uptake was insulin-sensitive. Incubation of lectin-purified insulin receptors with insulin resulted in a time- and concentration-dependent stimulation of phosphorylation of the tyrosine residue of an exogenous substrate poly (GLU, Tyr) (4:1). In addition, insulin also stimulated the autophosphorylation of the β-subunit of the insulin receptors. These observations corroborate our contentio that insulin exerts neuromodulation effects mediated by the specific insulin receptors in the brain.

Original languageEnglish
Pages (from-to)247-256
Number of pages10
JournalBrain Research
Volume417
Issue number2
DOIs
StatePublished - 11 Aug 1987
Externally publishedYes

Keywords

  • Insulin receptor
  • Neuron
  • Norepinephrine uptake
  • Phosphorylation
  • α-Subunit
  • β-Subunit

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