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Monoamine receptors in the amygdaloid complex of the tree shrew ( Tupaia belangeri )
Author(s) -
Flügge Gabriele,
Ahrens Olaf,
Fuchs Eberhard
Publication year - 1994
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.903430409
Subject(s) - biology , serotonin , monoamine neurotransmitter , receptor , serotonergic , neuroscience , ligand (biochemistry) , medicine , rauwolscine , endocrinology , anatomy , prazosin , biochemistry , antagonist
Although it is well known that the mammalian amygdala comprises a heterogeneous complex of cytoarchitectonically and histochemically distinct nuclei, the association of these nuclei with different monoamine systems has not been described in detail. We therefore investigated the pattern of receptors for monoamines in the amygdala of the tree shrew ( Tupaia belangeri ). Binding sites for the α 2 ‐adrenoceptor ligand ( 3 H) rauwolscine, the α 1 ‐adrenoceptor ligand ( 3 H) prazosin, the β‐adrenoceptor ligand ( 125 I) iodocyanopindolol, and the serotonin 1A ‐receptor ligand ( 3 H) 8‐hydroxy‐2 (di‐n‐propylamino) tertralin were visualized by in vitro autoradiography, and anatomically localized by comparing the autoradiograms to Nissl‐ and acetylcholinesterase‐stained sections. To characterize binding of the radioligands pharmacologically, displacement experiments with different specific competitors were performed. Whereas the highest number of α 2 ‐adrenergic binding sites was detected in the medial and the central nucleus as well as in the intercalated nueclei, the majority of serotonin 1A binding sites was found in the magnocellular basal nucleus and the accessory basal nucleus, demonstrating a clear difference in the anatomy of the α 2 ‐adrenergic and the serotonin 1A receptor systems. In contrast, the pattern of α 1 ‐adrenoceptor binding partially overlaps with that of both former receptor types. While the number of α‐adrenergic and serotonin 1A binding sites is relatively high in the tree shrew amygdala, there is only a low number of β‐adrenergic binding sites in most nuclei. However, in the cortical nuclei, moderate to high numbers of binding sites for all radioligands are present. Therefore, according to our data on the tree shrew amygdala, which is anatomically similar to the amygdala of cats and primates, α 2 ‐adrenoceptors cover primarily the medial part of the amygdaloid formation and serotonin 1A ‐receptors predominantly occupy the basal nuclei, whereas α 1 ‐adrenoceptors are present in both parts of the formation. © 1994 Wiley‐Liss, Inc.