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Changes in exploratory activity following stimulation of hippocampal 5‐HT1A and 5‐HT1B receptors in the rat
Author(s) -
Buhot MarieChristine,
Naili Said
Publication year - 1995
Publication title -
hippocampus
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.767
H-Index - 155
eISSN - 1098-1063
pISSN - 1050-9631
DOI - 10.1002/hipo.450050306
Subject(s) - stimulation , neuroscience , hippocampal formation , agonist , habituation , cholinergic , serotonergic , 5 ht receptor , psychology , muscarinic acetylcholine receptor , hippocampus , receptor , chemistry , serotonin , biochemistry
The object exploration task allows the measure of changes in locomotor and exploratory activities, habituation, and reaction to a spatial change and to novelty. The effects of intrahippocampal (dorsal CA1 field) microinjections of serotonin 1 receptor (5‐HT1) agonists on these behavioral components were evaluated in the rat. 8‐Hydroxy‐2‐(din‐propylamino)‐tetralin (8‐OH‐DPAT,5 μg/μl) was used as a 5‐HT1A agonist, 3‐(1,2,5,6‐tetrahydropyrid‐4‐yl) pyrrolo[3,2‐b] pyrid‐5‐one (CP 93,129, 16 μg/μl) as a 5‐HT1B agonist, and scopolamine (10 μg/μl) as a muscarinic cholinergic antagonist. Scopolamine induced a long‐lasting increase in locomotor activity and a lack of reaction to spatial change; both these results are in agreement with the known crucial influence of the septo‐hippocampal cholinergic system in hippocampal functioning. Stimulation of 5‐HT1A and 5‐HT1B receptors induced a decrease in object exploration and habituation without affecting the retrieval of spatial information. But stimulation of hippocampal 5‐HT1B receptors induced a selective change in the animal's emotional state, i.e., an initial decrease in locomotor activity and a neophobic reaction in response to a new object; such effects did not occur following stimulation of 5HT1A receptors. These results have to be considered in the light of the anxiogenic propety of 5‐HT1B agonists. On the whole, they support the hypothesis of the involvement of the serotonergic system, via 5HT1A and 5‐HT1B receptors, in the modulation of hippocampal functions. © 1995 Wiley‐Liss, Inc.