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Ultrastructural immunocytochemical localization of neurotensin and the dopamine D 2 receptor in the rat nucleus accumbens
Author(s) -
Delle Donne Karen T.,
Sesack Susan R.,
Pickel Virginia M.
Publication year - 1996
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/(sici)1096-9861(19960805)371:4<552::aid-cne5>3.0.co;2-3
Subject(s) - nucleus accumbens , neurotensin , biology , dopamine , neuroscience , ultrastructure , dopamine receptor d2 , dopamine receptor , nucleus , immunocytochemistry , receptor , neuropeptide , endocrinology , anatomy , biochemistry
The neuroleptic‐like effects of neurotensin (NT) are thought to be due to interactions with dopamine (DA) acting primarily at D 2 receptors within the nucleus accumbens septi (Acb). Using electron microscopic dual labeling immunocytochemistry, we sought to demonstrate cellular substrates for functional interactions involving NT and DA D 2 receptors in the adult rat Acb. Peroxidase reaction product representing D 2 receptor‐like immunoreactivity (D 2 ‐LI) was seen along membranes of Golgi lamellae and multivesicular bodies of perikarya containing immunogold labeling representing NT‐LI. Dually labeled somata usually contained highly indented nuclei, a characteristic of aspiny neurons. Dendrites also occasionally colocalized the two immunomarkers. Other somata, dendrites, and all axon terminals were singly labeled with either NT‐LI or D 2‐ LI. In distinct sets of terminals, NT‐LI was commonly associated with large, dense‐cored vesicles, whereas D 2 ‐LI was found along the plasmalemma and over nearby small clear vesicles. Each type of terminal comprised ∼ 20% of synaptic input to NT‐immunoreactive dendrites. Similar proportions of terminals containing NT‐LI or D 2 ‐LI contacted unlabeled (∼ 55%) or NT‐labeled (∼ 35%) dendrites and, occasionally, were observed converging onto common dendrites. Terminals containing NT‐LI or D 2 ‐LI also were often closely apposed. These findings provide the first ultrastructural evidence that: (1) NT and D 2 receptors are colocalized in aspiny neurons and dendrites, (2) NT may produce a direct postsynaptic effect on neurons receiving input from terminals which are presynaptically modulated by DA via D 2 receptors, and (3) NT and DA acting at D 2 receptors may interact through presynaptic modulation of common axon terminals. © 1996 Wiley‐Liss, Inc.