Hippocampal neurotransmitter efflux during one-trial novel object recognition in rats.
Several lines of evidence point to a role for the hippocampal formation and contiguous temporal lobe structures in a variety of learning and memory paradigms. Presumably, these cognitive phenomena are mediated (and accompanied) by dynamic changes in neurochemical transmission that may differ between learning and recall phases. However, the neurotransmitter correlates of most memory-related tasks have not been thoroughly investigated. Here we used a one-trial object recognition paradigm paired with in vivo microdialysis to assess hippocampal acetylcholine (ACh), glutamate and GABA efflux when rats were exposed to familiar objects, and when given the option to explore familiar and novel objects. Rats preferentially explored the novel object over the familiar one when presented with the option. Regardless of object familiarity, object exploration was accompanied by an increase in hippocampal ACh efflux, while GABA efflux was unaffected. However, glutamate efflux was not increased above baseline levels by presentation of familiar objects, but was significantly enhanced in the presence of the novel object. These data suggest that the hippocampus, and in particular, hippocampal glutamate, may be involved in memory processes during novelty recognition paradigms.
Department of Pharmacology, Physiology and Neuroscience, University of South Carolina School of Medicine, Columbia, SC 29208, USA.
Emily M
EM
Stanley
Marlene A
MA
Wilson
Jim R
JR
Fadel
D000109:Acetylcholine / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D005106:Exploratory Behavior; D018698:Glutamic Acid / Q000378:metabolism; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D008568:Memory; D017551:Microdialysis; D018377:Neurotransmitter Agents / Q000378:metabolism*; D051381:Rats; D011916:Rats, Inbred F344; D021641:Recognition, Psychology; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D018377:Neurotransmitter Agents; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid; D000109:Acetylcholine