The Phosphoinositide Signal Transduction System Is Impaired in Bipolar Affective Disorder Brain

Authors

  • Richard S. Jope,

    Corresponding author
    1. Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama; and
    Search for more papers by this author
  • Ling Song,

    1. Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama; and
    Search for more papers by this author
  • Peter P. Li,

    1. Department of Psychiatry, Section of Biochemical Psychiatry, Clarke Institute of Psychiatry, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author
  • L. Trevor Young,

    1. Department of Psychiatry, Section of Biochemical Psychiatry, Clarke Institute of Psychiatry, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author
    • The present address of Dr. L. T. Young is Department of Psychiatry, McMaster University, Hamilton, Ontario, Canada.

  • Stephen J. Kish,

    1. Department of Psychiatry, Section of Biochemical Psychiatry, Clarke Institute of Psychiatry, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author
  • Mary A. Pacheco,

    1. Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham, Birmingham, Alabama; and
    Search for more papers by this author
  • Jerry J. Warsh

    1. Department of Psychiatry, Section of Biochemical Psychiatry, Clarke Institute of Psychiatry, University of Toronto, Toronto, Ontario, Canada
    Search for more papers by this author

Address correspondence and reprint requests to Dr. R. S. Jope at Department of Psychiatry and Behavioral Neurobiology, Sparks Center 1057, University of Alabama at Birmingham, Birmingham, AL 35294-0017, U.S.A.

Abstract

Abstract: The function of the phosphoinositide second messenger system was assessed in occipital, temporal, and frontal cortex obtained postmortem from subjects with bipolar affective disorder and matched controls by measuring the hydrolysis of [3H]phosphatidylinositol ([3H]PI) incubated with membrane preparations and several different stimulatory agents. Phospholipase C activity, measured in the presence of 0.1 mM Ca2+ to stimulate the enzyme, was not different in bipolar and control samples. G proteins coupled to phospholipase C were concentration-dependently activated by guanosine 5′-O-(3-thiotriphosphate) (GTPγS) and by NaF. GTPγS-stimulated [3H]PI hydrolysis was markedly lower (50%) at all tested concentrations (0.3–10 µM GTPγS) in occipital cortical membranes from bipolar compared with control subjects. Responses to GTPγS in temporal and frontal cortical membranes were similar in bipolars and controls, as were responses to NaF in all three regions. Brain lithium concentrations correlated directly with GTPγS-stimulated [3H]PI hydrolysis in bipolar occipital, but not temporal or frontal, cortex. Carbachol, histamine, trans-1-aminocyclopentyl-1,3-dicarboxylic acid, serotonin, and ATP each activated [3H]PI hydrolysis above that obtained with GTPγS alone, and these responses were similar in bipolars and controls except for deficits in the responses to carbachol and serotonin in the occipital cortex, which were equivalent to the deficit detected with GTPγS alone. Thus, among the three cortical regions examined there was a selective impairment in G protein-stimulated [3H]PI hydrolysis in occipital cortical membranes from bipolar compared with control subjects. These results directly demonstrate decreased activity of the phosphoinositide signal transduction system in specific brain regions in bipolar affective disorder.

Ancillary