title: Y1 receptors in the nucleus accumbens: ultrastructural localization and association with neuropeptide Y.
abstract: Neuropeptide Y (NPY) is present in aspiny neurons in the nucleus accumbens (NAc), which also contains moderate levels of ligand binding and mRNA for the Y1 receptor. To determine the potential functional sites for receptor activation, we examined the electron microscopic immunocytochemical localization of antipeptide antisera against the Y1 receptor in the rat NAc. We also combined immunogold and immunoperoxidase labeling to show that, in this region, Y1 receptors are present in certain somatodendritic and axonal profiles that contain NPY or that appose NPY containing neurons. The Y1-like immunoreactivity (Y1-LI) was seen occasionally along plasma membranes but was associated more commonly with smooth endoplasmic reticulum (SER) and tubulovesicular organelles in somata and dendrites of spiny and aspiny neurons. The mean density of immunoreactive dendrites and spines per unit volume was greater in the "motor-associated" core than in the shell of the NAc. Y1-LI was also seen in morphologically heterogenous axon terminals, including those forming asymmetric excitatory-type synapses, and in selective astrocytic processes near this type of junction. We conclude that Y1 receptors play a role in autoregulation of NPY-containing neurons but are also likely to be internalized along with endogenous NPY in NAc. Our results also implicate Y1 receptors in the NAc in post- and presynaptic effects of NPY and in glial functions involving excitatory neurotransmission. In addition, they suggest involvement of Y1 receptors in determining the output of a select population of neurons associated with motor control in the NAc core.
authors.affiliation: Department of Neurology and Neuroscience, Cornell University Medical College, New York, New York 10021, USA. pickel@med.cornell.edu
authors.forename: V M
authors.initials: VM
authors.lastname: Pickel
authors.forename: A G
authors.initials: AG
authors.lastname: Beck-Sickinger
authors.forename: J
authors.initials: J
authors.lastname: Chan
authors.forename: H A
authors.initials: HA
authors.lastname: Weiland
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001369:Axons / Q000648:ultrastructure; D002462:Cell Membrane / Q000648:ultrastructure; D002645:Chickens; D003712:Dendrites / Q000648:ultrastructure; D018871:Endoplasmic Reticulum, Smooth / Q000648:ultrastructure; D006801:Humans; D007106:Immune Sera; D008297:Male; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D009474:Neurons / Q000648:ultrastructure*; D009478:Neuropeptide Y / Q000032:analysis*; D009714:Nucleus Accumbens / Q000648:ultrastructure*; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017476:Receptors, Neuropeptide Y / Q000032:analysis*
chemical_list: D007106:Immune Sera; D009478:Neuropeptide Y; D010446:Peptide Fragments; D017476:Receptors, Neuropeptide Y; C097212:neuropeptide Y-Y1 receptor