Original Paper

Neurochemical Research

, Volume 31, Issue 6, pp 759-765

First online:

Measuring Brain Uptake and Incorporation into Brain Phosphatidylinositol of Plasma myo-[2H6]Inositol in Unanesthetized Rats: An Approach to Estimate In vivo Brain Phosphatidylinositol Turnover

  • Kaizong MaAffiliated withBrain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health
  • , Joseph DeutschAffiliated withBrain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health
  • , Nelly E. VillacresesAffiliated withBrain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health
  • , Thad A. RosenbergerAffiliated withBrain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health
  • , Stanley I. RapoportAffiliated withBrain Physiology and Metabolism Section, National Institute on Aging, National Institutes of Health
  • , H. Umesha ShettyAffiliated withBrain Physiology and Metabolism Section, National Institute on Aging, National Institutes of HealthMolecular Imaging Branch, National Institute of Mental Health, National Institutes of Health Email author 

Rent the article at a discount

Rent now

* Final gross prices may vary according to local VAT.

Get Access

Abstract

The in vivo rate of turnover of phosphatidylinositol (PtdIns) in brain is not known. In brain, certain receptor-mediated signal transduction involves metabolism of PtdIns and a method to measure its turnover in awake animals is useful in studying the effect of lithium and other therapeutic agents. In a method described here, rats were infused subcutaneously with myo-[2H6]inositol (Ins*) using an osmotic pump and, at 1 and 8 weeks, concentrations of free myo-inositol (Ins) and Ins* in plasma and brain were measured by GC-MS (chemical ionization). Also, PtdIns and PtdIns* together in brain were isolated, and Ins and Ins* from their headgroups were released enzymatically and specific activity of incorporated inositol was measured. The specific activity of inositol reached a steady state in plasma within 1 week of infusion, but not in brain even at 8 weeks. However, in brain, the specific activity of phosphatidylinositol was same as that of inositol at both time-points, suggestive of fast turnover of PtdIns. The animal experiment and the analytical methodology described here should be useful for measuring the rate of turnover of brain PtdIns in pathological and drug treatment conditions.

Keywords

myo-Inositol Phosphatidylinositol turnover Brain uptake GC-MS Stable isotope Osmotic pump Na+/myo-inositol cotransporter