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Hippocampus 5‐HT 1A ‐receptors attenuate cocaine‐induced hyperlocomotion and the increase in hippocampal but not nucleus accumbens 5‐HT
Author(s) -
Müller Christian P.,
Thönnessen Heike,
Barros Marilia,
Tomaz Carlos,
Carey Robert J.,
Huston Joseph P.
Publication year - 2004
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.10209
Subject(s) - nucleus accumbens , hippocampal formation , microdialysis , hippocampus , chemistry , 5 ht receptor , serotonin , agonist , neuroscience , receptor , medicine , endocrinology , pharmacology , central nervous system , psychology , biochemistry
Cocaine induces an increase in hippocampal and nucleus accumbens (Nac) serotonin (5‐HT) concentration parallel to locomotor activation. Both effects can be modulated by systemic 5‐HT 1A ‐receptor agonism/antagonism. Given the contribution of the hippocampus to spontaneous behavioral activity, these observations suggest a role for hippocampal 5‐HT as well in the modulation of cocaine effects on behavior. To determine the role of hippocampal 5‐HT 1A ‐receptors in cocaine effects on behavior and hippocampal 5‐HT release, we used in vivo microdialysis in freely moving rats. The 5‐HT 1A ‐receptor agonist, 8‐OH‐DPAT (0, 0.1, 1 and 10 μM), was applied locally into the hippocampus by reversed dialysis followed by a cocaine (10 mg/kg) or saline i.p. injection. The hippocampal 5‐HT 1A ‐receptor activation attenuated cocaine‐induced hyperlocomotion and rearing behavior dose‐dependently. Parallel to that, the cocaine‐induced 5‐HT increase was attenuated dose‐dependently in the hippocampus but was left unaffected in the Nac. The intra‐hippocampal application of 8‐OH‐DPAT affected neither behavioral activity nor 5‐HT concentration in the hippocampus and in the Nac. In accord with these findings, hippocampal 5‐HT 1A ‐receptors may not be directly involved in the regulation of spontaneous behavior or basal 5‐HT concentration in the hippocampus and Nac. However, the results indicate an inhibitory role of hippocampal 5‐HT 1A ‐receptors in cocaine‐induced hyperactivity and in the 5‐HT increase evoked by cocaine in the hippocampus but not in the Nac. © 2004 Wiley‐Liss, Inc.