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Posttraining estradiol injections enhance memory in ovariectomized rats: cholinergic blockade and synergism.
Neurobiol Learn Mem. 1997 Sep; 68(2):172-88.NL

Abstract

The present experiments examined acute posttraining estrogenic influences on memory in ovariectomized rats. In experiment 1 rats received a single 8-trial (30-s ITI) training session with a submerged escape platform located in the same quadrant of a circular water maze on all trials. Following trial 8, rats received a posttraining intraperitoneal injection of either an estradiol-cyclodextrin inclusion complex (0.1, 0.2, or 0.4 mg/kg) or saline. On a retention test session 24 h later, the escape latencies of rats given injections of estradiol (0.2 mg/kg) were significantly lower than those of saline-treated rats, indicating an enhancement of memory. Injections of estradiol delayed 2 h posttraining did not affect retention, demonstrating a time-dependent effect of estradiol on memory storage processes. In experiment 2a, posttraining injections of the cholinergic muscarinic receptor antagonist scopolamine (0.4 mg/kg) impaired memory in ovariectomized rats. In experiment 2b, the memory-enhancing effect of estradiol (0.2 mg/kg) was blocked by concurrent posttraining administration of a subeffective dose (0.1 mg/kg) of scopolamine, suggesting an interaction between estradiol and muscarinic cholinergic systems in memory modulation. In experiment 3a, posttraining injections of the cholinergic muscarinic receptor agonist oxotremorine (0.2 mg/kg) enhanced memory in ovariectomized rats. In experiment 3b, concurrent posttraining injection a subeffective dose of estradiol (0.1 mg/kg) and a subeffective dose of oxotremorine (0.1 mg/kg) enhanced memory, indicating a synergistic effect of estradiol and muscarinic receptor activation on memory.

Authors+Show Affiliations

Department of Psychology, University of New Orleans, Louisiana 70148, USA. mgpps@uno.eduNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

9322259

Citation

Packard, M G., and L A. Teather. "Posttraining Estradiol Injections Enhance Memory in Ovariectomized Rats: Cholinergic Blockade and Synergism." Neurobiology of Learning and Memory, vol. 68, no. 2, 1997, pp. 172-88.
Packard MG, Teather LA. Posttraining estradiol injections enhance memory in ovariectomized rats: cholinergic blockade and synergism. Neurobiol Learn Mem. 1997;68(2):172-88.
Packard, M. G., & Teather, L. A. (1997). Posttraining estradiol injections enhance memory in ovariectomized rats: cholinergic blockade and synergism. Neurobiology of Learning and Memory, 68(2), 172-88.
Packard MG, Teather LA. Posttraining Estradiol Injections Enhance Memory in Ovariectomized Rats: Cholinergic Blockade and Synergism. Neurobiol Learn Mem. 1997;68(2):172-88. PubMed PMID: 9322259.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Posttraining estradiol injections enhance memory in ovariectomized rats: cholinergic blockade and synergism. AU - Packard,M G, AU - Teather,L A, PY - 1997/10/10/pubmed PY - 1997/10/10/medline PY - 1997/10/10/entrez SP - 172 EP - 88 JF - Neurobiology of learning and memory JO - Neurobiol Learn Mem VL - 68 IS - 2 N2 - The present experiments examined acute posttraining estrogenic influences on memory in ovariectomized rats. In experiment 1 rats received a single 8-trial (30-s ITI) training session with a submerged escape platform located in the same quadrant of a circular water maze on all trials. Following trial 8, rats received a posttraining intraperitoneal injection of either an estradiol-cyclodextrin inclusion complex (0.1, 0.2, or 0.4 mg/kg) or saline. On a retention test session 24 h later, the escape latencies of rats given injections of estradiol (0.2 mg/kg) were significantly lower than those of saline-treated rats, indicating an enhancement of memory. Injections of estradiol delayed 2 h posttraining did not affect retention, demonstrating a time-dependent effect of estradiol on memory storage processes. In experiment 2a, posttraining injections of the cholinergic muscarinic receptor antagonist scopolamine (0.4 mg/kg) impaired memory in ovariectomized rats. In experiment 2b, the memory-enhancing effect of estradiol (0.2 mg/kg) was blocked by concurrent posttraining administration of a subeffective dose (0.1 mg/kg) of scopolamine, suggesting an interaction between estradiol and muscarinic cholinergic systems in memory modulation. In experiment 3a, posttraining injections of the cholinergic muscarinic receptor agonist oxotremorine (0.2 mg/kg) enhanced memory in ovariectomized rats. In experiment 3b, concurrent posttraining injection a subeffective dose of estradiol (0.1 mg/kg) and a subeffective dose of oxotremorine (0.1 mg/kg) enhanced memory, indicating a synergistic effect of estradiol and muscarinic receptor activation on memory. SN - 1074-7427 UR - https://www.unboundmedicine.com/medline/citation/9322259/Posttraining_estradiol_injections_enhance_memory_in_ovariectomized_rats:_cholinergic_blockade_and_synergism_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1074-7427(97)93785-0 DB - PRIME DP - Unbound Medicine ER -