Abstract
We found that spinorphin, a novel neuropeptide showed analgesia in a different manner compared with morphine. By measuring flexor responses induced by the intraplanter injection of substances, the presence of three different types of sensory neurons were demonstrated. Although spinorphin completely blocked 2-metylthioadenosine (2-MeS ATP, a P2X(3) agonist)-induced responses, morphine did not. On the other hand, morphine-induced blockade of bradykinin (BK, a B(2)-receptor agonist)-responses was attenuated by pertussis toxin (PTX) treatment, whereas that of spinorphin was not. Thus it is suggested that spinorphin has a spectrum of analgesia which covers the blockade of nociception insensitive to morphine.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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6-Cyano-7-nitroquinoxaline-2,3-dione / pharmacology
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Adenosine / analogs & derivatives*
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Adenosine / metabolism
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Analgesics, Opioid / pharmacology*
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Animals
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Animals, Newborn
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Bradykinin / metabolism
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Capsaicin / pharmacology
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Dizocilpine Maleate / pharmacology
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Dose-Response Relationship, Drug
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Excitatory Amino Acid Antagonists / pharmacology
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Male
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Mice
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Morphine / pharmacology*
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Neurons, Afferent / drug effects
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Neuroprotective Agents / pharmacology
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Oligopeptides / pharmacology*
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Pain / drug therapy*
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Pertussis Toxin
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Piperidines / pharmacology
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Protease Inhibitors / pharmacology*
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Purinergic Agonists*
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Thionucleosides / metabolism
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Time Factors
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Virulence Factors, Bordetella / pharmacology
Substances
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Analgesics, Opioid
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Excitatory Amino Acid Antagonists
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Neuroprotective Agents
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Oligopeptides
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Piperidines
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Protease Inhibitors
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Purinergic Agonists
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Thionucleosides
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Virulence Factors, Bordetella
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3-(2-methoxybenzylamino)-2-phenylpiperidine
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spinorphin
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2-methylthioadenosine
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Dizocilpine Maleate
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6-Cyano-7-nitroquinoxaline-2,3-dione
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Morphine
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Pertussis Toxin
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Adenosine
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Capsaicin
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Bradykinin