Abstract
The extracellularly recorded electrophysiological activity of single multireceptive dorsal horn neurons was markedly increased by ionophoretic administration of vasoactive intestinal polypeptide (VIP) or pituitary adenylate cyclase activating polypeptide (PACAP)-38. Some cells responded selectively to PACAP-38 (suggesting mediation by a PACAP receptor), whereas others responded to both VIP and PACAP-38 (suggesting a VIP1 and/or VIP2 receptor). Most non-nociceptive cells were unaffected by PACAP-38 and all were unaffected by VIP. The selectivity of VIP/PACAP receptor antagonists was established on cloned rat VIP1, VIP2 and PACAP receptors in vitro before their utilization to indicate the likely involvement of VIP1, and possibly PACAP receptors, in VIP- and PACAP-38-mediated responses of dorsal horn neurons. The VIP/PACAP receptor antagonists inhibited responses of multireceptive cells to sustained innocuous (brush) and noxious (mustard oil) stimuli, with a selectivity suggesting the involvement of VIP1 and PACAP receptors, although the participation by VIP2 receptors cannot be excluded. These data implicate both VIP and PACAP in regulating the basal responsiveness of multireceptive dorsal horn neurons to sensory stimuli.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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COS Cells
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Male
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Membrane Potentials / drug effects
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Neurons / drug effects
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Neurons / physiology*
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Neurons, Afferent / physiology*
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Neuropeptides / pharmacology*
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Neurotransmitter Agents / pharmacology*
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Peptide Fragments / pharmacology
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Pituitary Adenylate Cyclase-Activating Polypeptide
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Rats
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Rats, Wistar
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Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Pituitary Hormone / drug effects
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Receptors, Pituitary Hormone / physiology*
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Receptors, Vasoactive Intestinal Peptide / drug effects
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Receptors, Vasoactive Intestinal Peptide / physiology*
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Receptors, Vasoactive Intestinal Peptide, Type II
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Recombinant Proteins / metabolism
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Spinal Cord / drug effects
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Spinal Cord / physiology*
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Transfection
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Vasoactive Intestinal Peptide / analogs & derivatives
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Vasoactive Intestinal Peptide / pharmacology*
Substances
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Adcyap1 protein, rat
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Neuropeptides
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Neurotransmitter Agents
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Peptide Fragments
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Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Pituitary Adenylate Cyclase-Activating Polypeptide
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Receptors, Pituitary Hormone
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Receptors, Vasoactive Intestinal Peptide
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Receptors, Vasoactive Intestinal Peptide, Type II
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Recombinant Proteins
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Vasoactive Intestinal Peptide