Posttraining intrahippocampal estradiol injections enhance spatial memory in male rats: interaction with cholinergic systems.
Male Long-Evans rats received an 8-trial training session in a spatial water maze task, followed by a unilateral posttraining intrahippocampal injection of either estradiol (1.0 microgram/0.5 microliter) or saline. Retention was tested 24 hr later, and latency to escape was used as a measure of memory. Retention test escape latencies of rats given intrahippocampal injections of estradiol were lower than those of saline-treated rats, indicating an enhancement of memory. Intrahippocampal injections of estradiol delayed 2 hr posttraining did not affect retention. In Experiment 2, the memory enhancing effect of intrahippocampal injection of estradiol was blocked by peripheral administration of a subeffective dose (0.1 mg/kg) of the cholinergic antagonist scopolamine. Intrahippocampal injections of estradiol enhance memory in male rats, and estradiol may influence memory through an interaction with muscarinic cholinergic systems.
Department of Psychology, University of New Orleans, Louisiana 70148, USA. mgpps@uno.edu
M G
MG
Packard
J R
JR
Kohlmaier
G M
GM
Alexander
D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D018782:Maze Learning; D008568:Memory / Q000187:drug effects / Q000502:physiology*; D018727:Muscarinic Antagonists / Q000494:pharmacology*; D051381:Rats; D012601:Scopolamine / Q000494:pharmacology*; D013037:Spatial Behavior / Q000502:physiology*
D018727:Muscarinic Antagonists; D004958:Estradiol; D012601:Scopolamine