Memory retention is modulated by acute estradiol and progesterone replacement.
Ovarian hormones alter spine density of hippocampal granule and pyramidal cells in young adult and aging female rats (P. Miranda, C. L. Williams, & G. Einstein, 1999; C. S. Woolley, 1998). The present study used a delayed matching-to-place version of the water maze to investigate a behavioral correlate of these hormone-induced changes in hippocampal connectivity in 3- and 8-month-old female rats. When primed with 10-microg injections of estradiol 72 and 48 hr before testing, the memory retention of ovariectomized rats was improved compared with retention after priming with oil. A single injection of progesterone maintained this enhancement if testing occurred within 8 hr of the progesterone injection but not if testing occurred more than 24 hr after the progesterone injection. These findings indicate that estradiol and progesterone alter memory retention and suggest that these changes may be the result of hormone-induced increases in hippocampal connectivity.
Sandstrom
N J
NJ
Department of Psychology: Experimental, Duke University, Durham, North Carolina 27708, USA. Noah.Sandstrom@williams.edu
Williams
C L
CL
D000818:Animals; D003712:Dendrites / Q000187:drug effects; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D006624:Hippocampus / Q000187:drug effects; D018782:Maze Learning / Q000187:drug effects*; D009415:Nerve Net / Q000187:drug effects; D009474:Neurons / Q000187:drug effects; D011374:Progesterone / Q000494:pharmacology*; D017966:Pyramidal Cells / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D012153:Retention, Psychology / Q000187:drug effects*
D011374:Progesterone; D004958:Estradiol