PREGNENOLONE SULFATE ENHANCES POST-TRAINING MEMORY PROCESSES WHEN INJECTED IN VERY-LOW DOSES INTO LIMBIC SYSTEM STRUCTURES - THE AMYGDALA IS BY FAR THE MOST SENSITIVE
Jf. Flood et al., PREGNENOLONE SULFATE ENHANCES POST-TRAINING MEMORY PROCESSES WHEN INJECTED IN VERY-LOW DOSES INTO LIMBIC SYSTEM STRUCTURES - THE AMYGDALA IS BY FAR THE MOST SENSITIVE, Proceedings of the National Academy of Sciences of the United Statesof America, 92(23), 1995, pp. 10806-10810
Immediate post-training, stereotactically guided, intraparenchymal adm
inistration of pregnenolone sulfate (PS) into the amygdala, septum, ma
mmillary bodies, or caudate nucleus and of PS, dehydroepiandrosterone
sulfate, and corticosterone into the hippocampus was performed in mice
that had been weakly trained in a foot-shock active avoidance paradig
m. Intrahippocampal injection of PS resulted in memory enhancement (ME
) at a lower dose than was found with dehydroepiandrosterone sulfate a
nd corticosterone, Intraamygdally administered PS was approximately 10
(4) times more potent on a molar basis in producing ME than when PS wa
s injected into the hippocampus and approximately 10(5) times more pot
ent than when injected into the septum or mammillary bodies. ME did no
t occur on injection of PS into the caudate nucleus over the range of
doses tested in the other brain structures, The finding that fewer tha
n 150 molecules of PS significantly enhanced post-training memory proc
esses when injected into the amygdala establishes PS as the most poten
t memory enhancer yet reported and the amygdala as the most sensitive
brain region for ME by any substance yet tested.