Use of cognitive strategies in rats: the role of estradiol and its interaction with dopamine.
Accumulating evidence suggests a role for estrogen in the use of a particular cognitive strategy when solving a maze task. In order to confirm the role of estrogen in this phenomenon, ovariectomized (OVX) female rats receiving either high ( approximately 90 pg/ml) or low ( approximately 32 pg/ml) circulating levels of 17beta-estradiol benzoate (E2) performed a plus maze task for a reward. Consistent with previous research, OVX rats receiving low levels of E2 utilized a striatum-mediated response strategy while OVX rats administered high levels of E2 employed a hippocampus-mediated place strategy. Furthermore, following a systemic injection of a moderate dose of either a dopamine D1 (SKF 83566, 0.1 mg/kg IP) or D2 (raclopride, 0.5 mg/kg IP) receptor antagonist, low E2 rats were seen to use the opposite strategy and exercise a hippocampus-mediated place strategy in order to obtain the reward. At the same doses, high E2 rats did not change from using a place strategy. At a lower dose, these drugs shifted high E2 rats such that they showed an equal propensity for either strategy; this was not observed in low E2 rats. These results corroborate previous findings that E2 plays a significant role in the use of either a response or place strategy when solving a maze for a reward. In addition, the shift in strategy after dopamine receptor blockade implies the importance of central dopamine function in selecting a cognitive strategy to solve such tasks. It is suggested that estrogen alters cognitive strategy not only by improving hippocampal function, but also by altering dopamine-regulated striatal function.
Quinlan
Matthew G
MG
Center for Studies in Behavioral Neurobiology, Concordia University, SP-244, 7141 Sherbrooke Street West, Montreal, QC, Canada H4B 1R6.
Hussain
Dema
D
Brake
Wayne G
WG
D000818:Animals; D003071:Cognition / Q000502:physiology; D004298:Dopamine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000008:administration & dosage / Q000502:physiology*; D030762:Estrous Cycle / Q000502:physiology; D005260:Female; D006624:Hippocampus / Q000378:metabolism*; D018782:Maze Learning / Q000502:physiology*; D017072:Neostriatum / Q000378:metabolism*; D009949:Orientation / Q000502:physiology; D011340:Problem Solving / Q000502:physiology*; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley
D004958:Estradiol; D004298:Dopamine