Ultrastructural immunocytochemical localization of neurotensin and the dopamine D2 receptor in the rat nucleus accumbens

Abstract

The neuroleptic-like effects of neurotensin (NT) are thought to be due to interactions with dopamine (DA) acting primarily at D2 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 D2 receptors in the adult rat Acb. Peroxidase reaction product representing D2 receptor-like immunoreactivity (D2-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 D2-LI. In distinct sets of terminals, NT-LI was commonly associated with large, dense-cored vesicles, whereas D2-LI was found along the plasmalemma and over nearby small clear vesicles. Each type of terminal comprised approximately 20% of synaptic input to NT-immunoreactive dendrites. Similar proportions of terminals containing NT-LI or D2-LI contacted unlabeled (approximately 55%) or NT-labeled (approximately 35%) dendrites and, occasionally, were observed converging onto common dendrites. Terminals containing NT-LI or D2-LI also were often closely apposed. These findings provide the first ultrastructural evidence that: (1) NT and D2 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 D2 receptors, and (3) NT and DA acting at D2 receptors may interact through presynaptic modulation of common axon terminals.

Estrogen receptor α and G-protein coupled estrogen receptor 1 are localized to GABAergic neurons in the dorsal striatum

“…Both ERα- and GPER1- IRs were observed at mitochondrial membranes, again paralleling findings from the previous study in the STR [7]. Also consistent with previous findings, GABA-IR was commonly observed in terminals, dendrites, and neuronal perikarya in the STR; axons and dendritic spines with GABA-IR were infrequently observed [25,26]. …”

Dopamine Axon Varicosities in the Prelimbic Division of the Rat Prefrontal Cortex Exhibit Sparse Immunoreactivity for the Dopamine Transporter

“…The specific immunoperoxidase reaction product for DAT was identified as an electron-dense flocculent precipitate that accumulated within the cytoplasm, along the inner plasmalemmal surface, and along the outer membranes of organelles, including synaptic vesicles. Such flocculent precipitate can be distinguished from other electron dense structures in the tissue, even when it is present at low levels (Sesack et al, 1994;Delle Donne et al, 1996. Furthermore, this flocculent product was not observed in presumed unlabeled structures in the immediately adjacent neuropil or in any structures viewed at greater depths from the surface.…”

Differential subcellular localization of two dopamine D2 receptor isoforms in transfected NG108‐15 cells

“…Studies of the subcellular localization of D2R by immuno‐electron microscopy have shown that D2R was detected not only in the plasma membrane region but also in intracellular compartments such as the Golgi apparatus and endoplasmic reticulum (Hersch et al . 1995; Delle et al . 1996).…”