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Rabbit forebrain cholinergic system: Morphological characterization of nuclei and distribution of cholinergic terminals in the cerebral cortex and hippocampus
Author(s) -
Varga Csaba,
Härtig Wolfgang,
Grosche Jens,
Keijser Jan,
Luiten Paul G.M.,
Seeger Johannes,
Brauer Kurt,
Harkany Tibor
Publication year - 2003
Publication title -
journal of comparative neurology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.855
H-Index - 209
eISSN - 1096-9861
pISSN - 0021-9967
DOI - 10.1002/cne.10673
Subject(s) - basal forebrain , nucleus basalis , cholinergic , substantia innominata , cholinergic neuron , choline acetyltransferase , neuroscience , biology , cholinergic fibers , vesicular acetylcholine transporter , globus pallidus , calbindin , hippocampus , cerebral cortex , basal ganglia , central nervous system , immunohistochemistry , immunology
Although the rabbit brain, in particular the basal forebrain cholinergic system, has become a common model for neuropathological changes associated with Alzheimer's disease, detailed neuroanatomical studies on the morphological organization of basal forebrain cholinergic nuclei and on their output pathways are still awaited. Therefore, we performed quantitative choline acetyltransferase (ChAT) immunocytochemistry to localize major cholinergic nuclei and to determine the number of respective cholinergic neurons in the rabbit forebrain. The density of ChAT‐immunoreactive terminals in layer V of distinct neocortical territories and in hippocampal subfields was also measured. Another cholinergic marker, the low‐affinity neurotrophin receptor (p75 NTR ), was also employed to identify subsets of cholinergic neurons. Double‐immunofluorescence labeling of ChAT and p75 NTR , calbindin D‐28k (CB), parvalbumin, calretinin, neuronal nitric oxide synthase (nNOS), tyrosine hydroxylase, or substance P was used to elucidate the neuroanatomical borders of cholinergic nuclei and to analyze the neurochemical complexity of cholinergic cell populations. Cholinergic projection neurons with heterogeneous densities were found in the medial septum, vertical and horizontal diagonal bands of Broca, ventral pallidum, and magnocellular nucleus basalis (MBN)/substantia innominata (SI) complex; cholinergic interneurons were observed in the caudate nucleus, putamen, accumbens nucleus, and olfactory tubercule, whereas the globus pallidus was devoid of cholinergic nerve cells. Cholinergic interneurons were frequently present in the hippocampus and to a lesser extent in cerebral cortex. Cholinergic projection neurons, except those localized in SI, abundantly expressed p75 NTR , and a subset of cholinergic neurons in posterior MBN was immunoreactive for CB and nNOS. A strict laminar distribution pattern of cholinergic terminals was recorded both in the cerebral cortex and in CA1–CA3 and dentate gyrus of the hippocampus. In summary, the structural organization and chemoarchitecture of rabbit basal forebrain may be considered as a transition between that of rodents and that of primates. J. Comp. Neurol. 460:597–611, 2003. © 2003 Wiley‐Liss, Inc.