title: Cell type-specific postsynaptic effects of neuropeptide Y in substantia gelatinosa neurons of the rat spinal cord.
abstract: Cellular mechanisms of antinociceptive action of neuropeptide Y were investigated in substantia gelatinosa (SG) neurons in rat spinal cord slices. Somatic and synaptic effects of NPY were compared in two subpopulations of cells with different firing patterns, tonic (TFNs), and delayed firing (DFNs) neurons. For the study, TFNs were selected on morphological basis: they had appearance of central and radial but not islet cells, and are likely excitatory interneurons in dorsal horn networks. In their turn, DFNs were classified as radial and vertical cells. 0.3 μM NPY via Y1 receptors activated hyperpolarizing postsynaptic current of GIRK type in majority of TFNs (∼77%) but not DFNs (∼8%). Miniature synaptic currents in all neurons were seen as a mixture of excitatory (mEPSCs) and inhibitory (mIPSCs), the frequency of the former being ∼5 times greater. The mEPSCs were mediated by glutamate receptors of AMPA subtype, while the dominant part of mIPSCs--by glycine receptors. In all cell types, NPY moderately depressed the frequency of both mEPSCs and mIPSCs; the effects occurred via Y2 and Y1 receptors, respectively. The data suggest that behavioral NPY-evoked antinociception is achieved via postsynaptic hyperpolarization of majority of TFNs (assumingly, excitatory interneurons) via Y1 receptors and depression of the mEPSCs via Y2 receptors.
authors.affiliation: Department of General Physiology, Bogomoletz Institute of Physiology, Kiev 01024, Ukraine. igorm@biph.kiev.ua
authors.forename: Igor V
authors.initials: IV
authors.lastname: Melnick
mesh_terms: D000818:Animals; D009474:Neurons / Q000187:drug effects* / Q000502:physiology; D009478:Neuropeptide Y / Q000378:metabolism / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley; D017476:Receptors, Neuropeptide Y / Q000819:agonists / Q000037:antagonists & inhibitors; D013116:Spinal Cord / Q000187:drug effects* / Q000502:physiology; D013376:Substantia Gelatinosa / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D009435:Synaptic Transmission
chemical_list: D009478:Neuropeptide Y; D017476:Receptors, Neuropeptide Y