In:
European Journal of Neuroscience, Wiley, Vol. 15, No. 10 ( 2002-05), p. 1669-1680
Abstract:
The effects of histaminergic ligands on both ACh spontaneous release from the hippocampus and the expression of c‐fos in the medial septum–diagonal band (MSA‐DB) of freely moving rats were investigated. Because the majority of cholinergic innervation to the hippocampus is provided by MSA‐DB neurons, we used the dual‐probe microdialysis technique to apply drugs to the MSA‐DB and record the induced effects in the projection area. Perfusion of MSA‐DB with high‐KCl medium strongly stimulated hippocampal ACh release which, conversely, was significantly reduced by intra‐MSA‐DB administration of tetrodotoxin. Histamine or the H 2 receptor agonist dimaprit, applied directly to the hippocampus, failed to alter ACh release. Conversely, perfusion of MSA‐DB with these two compounds increased ACh release from the hippocampus. Also, thioperamide and ciproxifan, two H 3 receptor antagonists, administered into MSA‐DB, increased the release of hippocampal ACh, whereas R‐α‐methylhistamine, an H 3 receptor agonist, produced the opposite effect. The blockade of MSA‐DB H 2 receptors, caused by local perfusion with the H 2 receptor antagonist cimetidine, moderated the spontaneous release of hippocampal ACh and antagonized the facilitation produced by H 3 receptor antagonists. Triprolidine, an H 1 receptor antagonist, was without effect. Moreover, cells expressing c‐fos immunoreactivity were significantly more numerous in ciproxifan‐ or thioperamide‐treated rats than in controls, although no colocalization of anti‐c‐fos and anti‐ChAT immunoreactivity was observed. These results indicate a role for endogenous histamine in modulating the cholinergic tone in the hippocampus.
Type of Medium:
Online Resource
ISSN:
0953-816X
,
1460-9568
DOI:
10.1046/j.1460-9568.2002.02005.x
Language:
English
Publisher:
Wiley
Publication Date:
2002
detail.hit.zdb_id:
2005178-5
SSG:
12
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