Fig. 6.

The plasma concentration of 13-cis-RA after a single injection of RA at 1 mg/kg and the entry of RA into the hippocampus to bind to cellular RA-binding protein I (CRABPI). (A) The plasma RA concentration quickly reached 2.2 μg/ml after 20 min and was down to 0.3 μg/ml after 2 h(n = 3). (B) The movement of RA into hippocampal cells could be shown by separating hippocampal CRABPI by isoelectric focusing (which runs at a pI of 4.8) and eluting the RA bound to this. •, hippocampus without RA; ○, hippocampus plus RA.