title: Enkephalin and neuropeptide-Y interaction in the intergeniculate leaflet network, a part of the mammalian biological clock.
abstract: The intergeniculate leaflet (IGL) is a flat thalamic nucleus implicated in the modulation of circadian rhythmicity. In rat, two main GABAergic subpopulations can be distinguished in the IGL: neurons synthesizing neuropeptide Y (NPY), which directly innervates the suprachiasmatic nuclei, and enkephalinergic cells, which connect contralaterally located leaflets. The aim of this study was to evaluate possible effects of inner IGL neurotransmitters on the spontaneous and synaptic activity of IGL neurons. The data presented in this article provide evidence that enkephalin, and not NPY, could act upon the majority of IGL neurons. Moreover, we investigated the type of opioid receptor activated by enkephalin and showed that the μ-receptor is functionally predominant in the IGL. The application of met-enkephalin not only robustly hyperpolarized IGL neurons (both putatively NPY-synthesizing and putatively enkephalinergic neurons), but it also was able to inhibit GABAergic and glutamatergic synaptic transmission. Based on this and previous studies, we hypothesize that IGL enkephalinergic neurons may act as powerful interneurons that inhibit themselves and NPY-synthesizing neurons, also in the contralaterally located IGL.
authors.affiliation: Department of Neurophysiology and Chronobiology, Jagiellonian University in Krakow, Gronostajowa 9, 30-387 Krakow, Poland.
authors.forename: K
authors.initials: K
authors.lastname: Palus
authors.affiliation: Department of Neurophysiology and Chronobiology, Jagiellonian University in Krakow, Gronostajowa 9, 30-387 Krakow, Poland.
authors.forename: L
authors.initials: L
authors.lastname: Chrobok
authors.affiliation: Faculty of Chemistry, Jagiellonian University in Krakow, Ingardena 3, 30-060 Krakow, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Kepczynski
authors.affiliation: Department of Neurophysiology and Chronobiology, Jagiellonian University in Krakow, Gronostajowa 9, 30-387 Krakow, Poland. Electronic address: marian.lewandowski@uj.edu.pl.
authors.forename: M H
authors.initials: MH
authors.lastname: Lewandowski
mesh_terms: D000818:Animals; D001683:Biological Clocks / Q000187:drug effects / Q000502:physiology*; D004745:Enkephalins / Q000008:administration & dosage / Q000378:metabolism*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D018698:Glutamic Acid / Q000378:metabolism; D007150:Immunohistochemistry; D053444:Inhibitory Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D008297:Male; D055369:Miniature Postsynaptic Potentials / Q000187:drug effects / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009478:Neuropeptide Y / Q000378:metabolism*; D018377:Neurotransmitter Agents / Q000008:administration & dosage; D018408:Patch-Clamp Techniques; D017208:Rats, Wistar; D009435:Synaptic Transmission / Q000187:drug effects / Q000502:physiology; D013787:Thalamic Nuclei / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D046509:Tissue Culture Techniques; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
chemical_list: D004745:Enkephalins; D009478:Neuropeptide Y; D018377:Neurotransmitter Agents; D018698:Glutamic Acid; D005680:gamma-Aminobutyric Acid
keywords: enkephalin; intergeniculate leaflet; neuropeptide Y; patch clamp; synaptic transmission