Estradiol potentiates acetylcholine and glutamate-mediated post-trial memory processing in the hippocampus.
There is increasing evidence that estrogen is involved in CNS activity, particularly memory. Several studies have suggested that estrogen improves memory by enhancing cholinergic and glutamatergic activity. In the present studies, we examined the effects of administration into the hippocampus of 17 beta-estradiol and estrone on retention of T-maze footshock avoidance in female ovariectomized mice. Both 17 beta-estradiol and estrone improved retention on an equimolar basis in a dose-dependent fashion. We then used the T-maze footshock paradigm to test whether a dose of 17 beta-estradiol ineffective as a single injection (subthreshold) could potentiate the effects of arecoline, a cholinergic agonist, or L-glutamate, a glutamatergic agonist, on retention. The dose of either arecoline or L-glutamate needed to improve retention was reduced at least ten-fold by the low dose of 17 beta-estradiol. These findings support the concept that estrogen improves memory by potentiating the activity of the cholinergic and glutamatergic systems.
Farr
S A
SA
Geriatric Research Education and Clinical Center (GRECC), VA Medical Center, St. Louis, MO, USA. farra52@aol.com
Banks
W A
WA
Morley
J E
JE
D000109:Acetylcholine / Q000502:physiology*; D000818:Animals; D001115:Arecoline / Q000494:pharmacology; D001362:Avoidance Learning / Q000187:drug effects / Q000502:physiology; D018679:Cholinergic Agonists / Q000494:pharmacology; D004357:Drug Synergism; D004597:Electroshock; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D018698:Glutamic Acid / Q000494:pharmacology* / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology*; D018782:Maze Learning / Q000187:drug effects / Q000502:physiology; D008568:Memory / Q000187:drug effects* / Q000502:physiology; D051379:Mice; D008815:Mice, Inbred Strains; D008845:Microinjections; D010052:Ovariectomy
D018679:Cholinergic Agonists; D018698:Glutamic Acid; D001115:Arecoline; D004958:Estradiol; D000109:Acetylcholine