TY - JOUR
T1 - Measuring brain uptake and incorporation into brain phosphatidylinositol of plasma myo-[2H6]inositol in unanesthetized rats
T2 - An approach to estimate in vivo brain phosphatidylinositol turnover
AU - Ma, Kaizong
AU - Deutsch, Joseph
AU - Villacreses, Nelly E.
AU - Rosenberger, Thad A.
AU - Rapoport, Stanley I.
AU - Shetty, H. Umesha
PY - 2006/6
Y1 - 2006/6
N2 - 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.
AB - 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.
KW - Brain uptake
KW - GC-MS
KW - myo-Inositol
KW - Na/myo-inositol cotransporter
KW - Osmotic pump
KW - Phosphatidylinositol turnover
KW - Stable isotope
UR - http://www.scopus.com/inward/record.url?scp=33746347388&partnerID=8YFLogxK
U2 - 10.1007/s11064-006-9080-4
DO - 10.1007/s11064-006-9080-4
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C2 - 16791473
AN - SCOPUS:33746347388
SN - 0364-3190
VL - 31
SP - 759
EP - 765
JO - Neurochemical Research
JF - Neurochemical Research
IS - 6
ER -