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Differential modulation of frontal cortex acetylcholine by injection of substance P into the nucleus basalis magnocellularis region in the freely‐moving vs. the anesthetized preparation
Author(s) -
De Souza Silva Maria Angelica,
Hasenöhrl Rüdiger U.,
Tomaz Carlos,
Schwarting Rainer K.W.,
Huston Joseph P.
Publication year - 2000
Publication title -
synapse
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.809
H-Index - 106
eISSN - 1098-2396
pISSN - 0887-4476
DOI - 10.1002/1098-2396(20001201)38:3<243::aid-syn3>3.0.co;2-g
Subject(s) - nucleus basalis , microdialysis , acetylcholine , neurochemical , cholinergic , chemistry , neuroscience , cortex (anatomy) , frontal cortex , acetylcholinesterase , extracellular , medicine , anesthesia , endocrinology , cholinergic neuron , pharmacology , psychology , biochemistry , enzyme
In vivo microdialysis was used to assess the effects of unilateral substance P (SP) injection into the nucleus basalis magnocellularis on extracellular levels of acetylcholine (ACh) in the frontal cortex, either in freely moving or urethane‐anesthetized rats. The results show that the neurochemical effects of SP are critically dependent on the choice of the experimental preparation: In the freely‐moving rat, the injection procedure led to behavioral and concurrent bilateral cholinergic activation in the frontal cortex. This cholinergic activation was ipsilaterally reduced by intrabasalis injection of SP (1 ng), indicating that the peptide exerted an inhibitory influence on the neurochemical effect exerted by handling, intracranial needle insertion, and vehicle injection. In the anesthetized preparation, SP had a biphasic dose‐dependent action on cortical ACh: a short‐lasting ipsilateral increase immediately after injection (especially with 1 ng), and a delayed bilateral increase after more than 2 h (10, 100 ng). The procedure of inserting the injection needle moderately increased cortical ACh levels. Methodologically, these data are discussed with respect to the importance of using anesthetized vs. freely moving rats and the effects of intraparenchymal injections. Synapse 38:243–253, 2000. © 2000 Wiley‐Liss, Inc.