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Dynorphin-immunoreactive terminals in the rat nucleus accumbens: cellular sites for modulation of target neurons and interactions with catecholamine afferents.
J Comp Neurol. 1994 Mar 01; 341(1):1-15.JC

Abstract

Dynorphin facilitates conditioned place aversion and reduces locomotor activity through mechanisms potentially involving direct activation of target neurons or release of catecholamines from afferents in the nucleus accumbens. We examined the ultrastructural substrates underlying these actions by combining immunoperoxidase labeling for dynorphin 1-8 and immunogold silver labeling for the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH). The two markers were simultaneously visualized in single coronal sections through the rat nucleus accumbens. By light microscopy, dynorphin immunoreactivity was seen as patches of immunoreactive varicosities throughout all rostrocaudal levels of the nucleus accumbens. The dynorphin-immunoreactive terminals identified by electron microscopy ranged from 0.2 to 1.5 microns in cross-sectional diameter, contained numerous small (30-40 nm) clear vesicles, as well as one or more large (80-100 nm) dense core vesicles. From the dynorphin-immunoreactive terminals quantitatively examined in single sections, 74% (173/370) showed symmetric synaptic junctions mainly with large unlabeled dendrites. Of the dynorphin-immunoreactive terminals forming identifiable synapses, approximately 30% contacted more than one dendritic target. In addition, single dendrites frequently received convergent input from more than one dynorphin-labeled terminal. Irrespective of their dendritic associations, dynorphin-immunoreactive terminals also frequently showed close appositions with other axons and terminals; these included unlabeled (41%), TH-labeled (10%) or dynorphin-labeled axons (14%). In contrast to dynorphin-immunoreactive terminals, TH-labeled terminals formed primarily symmetric synapses with small dendrites and spines or lacked recognizable specializations in the plane of section analyzed. In some cases, single dendrites were postsynaptic to both dynorphin and TH-immunoreactive terminals. We conclude that dynorphin-immunoreactive terminals potently modulate, and most likely inhibit, target neurons in both subregions of the rat nucleus accumbens. This modulatory action could attenuate or potentiate incoming catecholamine signals on more distal dendrites of the accumbens neurons. The findings also suggest potential sites for presynaptic modulatory interactions involving dynorphin and catecholamine or other transmitters in apposed terminals.

Authors+Show Affiliations

Department of Neurology and Neuroscience, Cornell University Medical College, New York, New York 10021.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

7911809

Citation

Van Bockstaele, E J., et al. "Dynorphin-immunoreactive Terminals in the Rat Nucleus Accumbens: Cellular Sites for Modulation of Target Neurons and Interactions With Catecholamine Afferents." The Journal of Comparative Neurology, vol. 341, no. 1, 1994, pp. 1-15.
Van Bockstaele EJ, Sesack SR, Pickel VM. Dynorphin-immunoreactive terminals in the rat nucleus accumbens: cellular sites for modulation of target neurons and interactions with catecholamine afferents. J Comp Neurol. 1994;341(1):1-15.
Van Bockstaele, E. J., Sesack, S. R., & Pickel, V. M. (1994). Dynorphin-immunoreactive terminals in the rat nucleus accumbens: cellular sites for modulation of target neurons and interactions with catecholamine afferents. The Journal of Comparative Neurology, 341(1), 1-15.
Van Bockstaele EJ, Sesack SR, Pickel VM. Dynorphin-immunoreactive Terminals in the Rat Nucleus Accumbens: Cellular Sites for Modulation of Target Neurons and Interactions With Catecholamine Afferents. J Comp Neurol. 1994 Mar 1;341(1):1-15. PubMed PMID: 7911809.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Dynorphin-immunoreactive terminals in the rat nucleus accumbens: cellular sites for modulation of target neurons and interactions with catecholamine afferents. AU - Van Bockstaele,E J, AU - Sesack,S R, AU - Pickel,V M, PY - 1994/3/1/pubmed PY - 1994/3/1/medline PY - 1994/3/1/entrez SP - 1 EP - 15 JF - The Journal of comparative neurology JO - J. Comp. Neurol. VL - 341 IS - 1 N2 - Dynorphin facilitates conditioned place aversion and reduces locomotor activity through mechanisms potentially involving direct activation of target neurons or release of catecholamines from afferents in the nucleus accumbens. We examined the ultrastructural substrates underlying these actions by combining immunoperoxidase labeling for dynorphin 1-8 and immunogold silver labeling for the catecholamine synthesizing enzyme, tyrosine hydroxylase (TH). The two markers were simultaneously visualized in single coronal sections through the rat nucleus accumbens. By light microscopy, dynorphin immunoreactivity was seen as patches of immunoreactive varicosities throughout all rostrocaudal levels of the nucleus accumbens. The dynorphin-immunoreactive terminals identified by electron microscopy ranged from 0.2 to 1.5 microns in cross-sectional diameter, contained numerous small (30-40 nm) clear vesicles, as well as one or more large (80-100 nm) dense core vesicles. From the dynorphin-immunoreactive terminals quantitatively examined in single sections, 74% (173/370) showed symmetric synaptic junctions mainly with large unlabeled dendrites. Of the dynorphin-immunoreactive terminals forming identifiable synapses, approximately 30% contacted more than one dendritic target. In addition, single dendrites frequently received convergent input from more than one dynorphin-labeled terminal. Irrespective of their dendritic associations, dynorphin-immunoreactive terminals also frequently showed close appositions with other axons and terminals; these included unlabeled (41%), TH-labeled (10%) or dynorphin-labeled axons (14%). In contrast to dynorphin-immunoreactive terminals, TH-labeled terminals formed primarily symmetric synapses with small dendrites and spines or lacked recognizable specializations in the plane of section analyzed. In some cases, single dendrites were postsynaptic to both dynorphin and TH-immunoreactive terminals. We conclude that dynorphin-immunoreactive terminals potently modulate, and most likely inhibit, target neurons in both subregions of the rat nucleus accumbens. This modulatory action could attenuate or potentiate incoming catecholamine signals on more distal dendrites of the accumbens neurons. The findings also suggest potential sites for presynaptic modulatory interactions involving dynorphin and catecholamine or other transmitters in apposed terminals. SN - 0021-9967 UR - https://www.unboundmedicine.com/medline/citation/7911809/Dynorphin_immunoreactive_terminals_in_the_rat_nucleus_accumbens:_cellular_sites_for_modulation_of_target_neurons_and_interactions_with_catecholamine_afferents_ L2 - https://onlinelibrary.wiley.com/resolve/openurl?genre=article&sid=nlm:pubmed&issn=0021-9967&date=1994&volume=341&issue=1&spage=1 DB - PRIME DP - Unbound Medicine ER -