Multiphasic effect of morphine on the release of substance P from rat trigeminal nucleus slices
| Autor: | Lubna H. Abdullah, William Maixner, Heberto Suarez-Roca, John R. Zuniga, Sandra Madison |
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| Rok vydání: | 1992 |
| Předmět: |
Male
medicine.medical_specialty medicine.drug_class Narcotic Antagonists Radioimmunoassay Substance P (+)-Naloxone In Vitro Techniques Inhibitory postsynaptic potential chemistry.chemical_compound Opioid receptor Internal medicine medicine Animals Neurons Afferent Trigeminal Nerve Receptor Molecular Biology Morphine Naloxone General Neuroscience Rats Inbred Strains Rats Endocrinology Mechanism of action chemistry Chromatography Gel Excitatory postsynaptic potential Neurology (clinical) medicine.symptom Developmental Biology medicine.drug |
| Zdroj: | Brain Research. 579:187-194 |
| ISSN: | 0006-8993 |
| Popis: | It is generally accepted that morphine acts presynaptically to inhibit substance P (SP) release from afferent terminals in the trigeminal nucleus. Recent studies, however, provide evidence that opioids produce both inhibitory and excitatory effects on SP release which are concentration- and receptor subtype-dependent. In the present study, we have examined a wide range of morphine concentrations on K(+)-evoked SP release from rat trigeminal nucleus caudalis slices. Immunoreactive SP was measured in perfusates. Morphine produced multiphasic effects on K(+)-evoked SP release without affecting basal release. A very low nanomolar concentration (1 nM) suppressed release, higher nanomolar concentrations (100-300 nM) facilitated release, a low micromolar concentration (3 microM) suppressed release, and a higher micromolar concentration (30 microM) facilitated release. These effects were abolished by opioid receptor blockade with naloxone (30 nM). Thus, morphine produces a complex bi-directional modulation of SP release from TNC which is concentration- and possibly receptor subtype-dependent. |
| Databáze: | OpenAIRE |
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