Substance P excites GABAergic neurons in the mouse central amygdala through neurokinin 1 receptor activation.
Substance P (SP) is implicated in stress regulation and affective and anxiety-related behavior. Particularly high expression has been found in the main output region of the amygdala complex, the central amygdala (CE). Here we investigated the cellular mechanisms of SP in CE in vitro, taking advantage of glutamic acid decarboxylase-green fluorescent protein (GAD67-GFP) knockin mice that yield a reliable labeling of GABAergic neurons, which comprise 95% of the neuronal population in the lateral section of CE (CEl). In GFP-positive neurons within CEl, SP caused a membrane depolarization and increase in input resistance, associated with an increase in action potential firing frequency. Under voltage-clamp conditions, the SP-specific membrane current reversed at -101.5 ± 2.8 mV and displayed inwardly rectifying properties indicative of a membrane K(+) conductance. Moreover, SP responses were blocked by the neurokinin type 1 receptor (NK1R) antagonist L-822429 and mimicked by the NK1R agonist [Sar(9),Met(O2)(11)]-SP. Immunofluorescence staining confirmed localization of NK1R in GFP-positive neurons in CEl, predominantly in PKCδ-negative neurons (80%) and in few PKCδ-positive neurons (17%). Differences in SP responses were not observed between the major types of CEl neurons (late firing, regular spiking, low-threshold bursting). In addition, SP increased the frequency and amplitude of GABAergic synaptic events in CEl neurons depending on upstream spike activity. These data indicate a NK1R-mediated increase in excitability and GABAergic activity in CEl neurons, which seems to mostly involve the PKCδ-negative subpopulation. This influence can be assumed to increase reciprocal interactions between CElon and CEloff pathways, thereby boosting the medial CE (CEm) output pathway and contributing to the anxiogenic-like action of SP in the amygdala.
Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany; Neuronal Networks Group, Deutsches Zentrum für Neurodegenerative Erkrankungen (DZNE), Bonn, Germany.
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Sosulina
Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany;
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Strippel
Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany;
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Romo-Parra
Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany;
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Walter
Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany;
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Kanyshkova
Department of Pharmacology and Toxicology, Institute of Pharmacy, and Centre for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Insbruck, Austria; and.
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Sartori
Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany;
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Lange
Department of Pharmacology and Toxicology, Institute of Pharmacy, and Centre for Molecular Biosciences Innsbruck (CMBI), University of Innsbruck, Insbruck, Austria; and.
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Singewald
Institute of Physiology I, Westfälische Wilhelms-Universität Münster, Münster, Germany; papechris@ukmuenster.de.
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Pape
D000818:Animals; D066274:Central Amygdaloid Nucleus / Q000187:drug effects / Q000502:physiology*; D005455:Fluorescent Antibody Technique; D059330:GABAergic Neurons / Q000187:drug effects / Q000502:physiology*; D055879:Gene Knock-In Techniques; D005968:Glutamate Decarboxylase / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D064729:Neurokinin-1 Receptor Antagonists / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D010880:Piperidines / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D051745:Protein Kinase C-delta / Q000378:metabolism; D018040:Receptors, Neurokinin-1 / Q000378:metabolism*; D013373:Substance P / Q000378:metabolism*; D046509:Tissue Culture Techniques
C532739:N-((2-cyclopropoxy-5-(5-trifluomethyl)tetrazol-1-yl)benzyl)-2-phenylpiperidin-3-amine; D064729:Neurokinin-1 Receptor Antagonists; D010880:Piperidines; D018040:Receptors, Neurokinin-1; D049452:Green Fluorescent Proteins; D013373:Substance P; D051745:Protein Kinase C-delta; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1; D011188:Potassium
PKCδ; central amygdala; neurokinin type 1 receptor; substance P