The stereospecific effect of naloxone on rat dorsal horn neurones; inhibition in superficial laminae and excitation in deeper laminae. 1980

Maria Fitzgerald, and Clifford J Woolf
Department of Physiology, Middlesex Hospital Medical School, London W1P 6DB Great Britain Cerebral Functions Group, Department of Anatomy, University College London, London WC1E 6BT, Great Britain.

The effect of systemic naloxone on the activity evoked by C-fibre stimulation in dorsal horn neurones of the rat spinal cord has been investigated. Recordings were made in unanaesthetized, decerebrate spinalized rats. Fifteen units were recorded from laminae 4 and 5 of the dorsal horn, 11 of these units were excited by naloxone (0.2--1.0 mg/kg). The onset of this excitation was after 20 sec to 5 min and recovery to control levels occurred within 15--40 min. Of 17 units recorded in substantia gelatinosa of the dorsal horn, 13 were inhibited by the naloxone. The latency of onset of this inhibition was short (2--10 sec) and the effect persisted for 5--10 min. The effects were largely restricted to C-fibre evoked activity although sometimes A delta responses were similarly altered. Neurones stimulated by A beta-fibre threshold, or whose sole afferent input were A beta-fibres, were unaffected by the naloxone. The stereoisomer of naloxone, (+)naloxone which is inactive in opiate receptor binding tests, failed to produce the same changes found with (-)naloxone in 17 units. These results show a differential effect of naloxone on neurones in the dorsal horn which respond to C-fibre input. Units in the substantia gelatinosa are inhibited while units in deeper laminae are excited by naloxone. These effects are likely to be mediated by the blockade of endogenous opioids in the spinal cord.

UI MeSH Term Description Entries
D008297 Male Males
D009270 Naloxone A specific opiate antagonist that has no agonist activity. It is a competitive antagonist at mu, delta, and kappa opioid receptors. MRZ 2593-Br,MRZ-2593,Nalone,Naloxon Curamed,Naloxon-Ratiopharm,Naloxone Abello,Naloxone Hydrobromide,Naloxone Hydrochloride,Naloxone Hydrochloride Dihydride,Naloxone Hydrochloride, (5 beta,9 alpha,13 alpha,14 alpha)-Isomer,Naloxone, (5 beta,9 alpha,13 alpha,14 alpha)-Isomer,Narcan,Narcanti,Abello, Naloxone,Curamed, Naloxon,Dihydride, Naloxone Hydrochloride,Hydrobromide, Naloxone,Hydrochloride Dihydride, Naloxone,Hydrochloride, Naloxone,MRZ 2593,MRZ 2593 Br,MRZ 2593Br,MRZ2593,Naloxon Ratiopharm
D009412 Nerve Fibers Slender processes of NEURONS, including the AXONS and their glial envelopes (MYELIN SHEATH). Nerve fibers conduct nerve impulses to and from the CENTRAL NERVOUS SYSTEM. Cerebellar Mossy Fibers,Mossy Fibers, Cerebellar,Cerebellar Mossy Fiber,Mossy Fiber, Cerebellar,Nerve Fiber
D009413 Nerve Fibers, Myelinated A class of nerve fibers as defined by their structure, specifically the nerve sheath arrangement. The AXONS of the myelinated nerve fibers are completely encased in a MYELIN SHEATH. They are fibers of relatively large and varied diameters. Their NEURAL CONDUCTION rates are faster than those of the unmyelinated nerve fibers (NERVE FIBERS, UNMYELINATED). Myelinated nerve fibers are present in somatic and autonomic nerves. A Fibers,B Fibers,Fiber, Myelinated Nerve,Fibers, Myelinated Nerve,Myelinated Nerve Fiber,Myelinated Nerve Fibers,Nerve Fiber, Myelinated
D010146 Pain An unpleasant sensation induced by noxious stimuli which are detected by NERVE ENDINGS of NOCICEPTIVE NEURONS. Suffering, Physical,Ache,Pain, Burning,Pain, Crushing,Pain, Migratory,Pain, Radiating,Pain, Splitting,Aches,Burning Pain,Burning Pains,Crushing Pain,Crushing Pains,Migratory Pain,Migratory Pains,Pains, Burning,Pains, Crushing,Pains, Migratory,Pains, Radiating,Pains, Splitting,Physical Suffering,Physical Sufferings,Radiating Pain,Radiating Pains,Splitting Pain,Splitting Pains,Sufferings, Physical
D003655 Decerebrate State A condition characterized by abnormal posturing of the limbs that is associated with injury to the brainstem. This may occur as a clinical manifestation or induced experimentally in animals. The extensor reflexes are exaggerated leading to rigid extension of the limbs accompanied by hyperreflexia and opisthotonus. This condition is usually caused by lesions which occur in the region of the brainstem that lies between the red nuclei and the vestibular nuclei. In contrast, decorticate rigidity is characterized by flexion of the elbows and wrists with extension of the legs and feet. The causative lesion for this condition is located above the red nuclei and usually consists of diffuse cerebral damage. (From Adams et al., Principles of Neurology, 6th ed, p358) Decerebrate Posturing,Decorticate Rigidity,Decorticate State,Rigidity, Decerebrate,Rigidity, Decorticate,Decerebrate Posturings,Decerebrate Rigidity,Decerebrate States,Decorticate Rigidities,Decorticate States,Posturing, Decerebrate,Posturings, Decerebrate,Rigidities, Decorticate,State, Decerebrate,States, Decerebrate
D004723 Endorphins One of the three major groups of endogenous opioid peptides. They are large peptides derived from the PRO-OPIOMELANOCORTIN precursor. The known members of this group are alpha-, beta-, and gamma-endorphin. The term endorphin is also sometimes used to refer to all opioid peptides, but the narrower sense is used here; OPIOID PEPTIDES is used for the broader group. Endorphin
D005071 Evoked Potentials Electrical responses recorded from nerve, muscle, SENSORY RECEPTOR, or area of the CENTRAL NERVOUS SYSTEM following stimulation. They range from less than a microvolt to several microvolts. The evoked potential can be auditory (EVOKED POTENTIALS, AUDITORY), somatosensory (EVOKED POTENTIALS, SOMATOSENSORY), visual (EVOKED POTENTIALS, VISUAL), or motor (EVOKED POTENTIALS, MOTOR), or other modalities that have been reported. Event Related Potential,Event-Related Potentials,Evoked Potential,N100 Evoked Potential,P50 Evoked Potential,N1 Wave,N100 Evoked Potentials,N2 Wave,N200 Evoked Potentials,N3 Wave,N300 Evoked Potentials,N4 Wave,N400 Evoked Potentials,P2 Wave,P200 Evoked Potentials,P50 Evoked Potentials,P50 Wave,P600 Evoked Potentials,Potentials, Event-Related,Event Related Potentials,Event-Related Potential,Evoked Potential, N100,Evoked Potential, N200,Evoked Potential, N300,Evoked Potential, N400,Evoked Potential, P200,Evoked Potential, P50,Evoked Potential, P600,Evoked Potentials, N100,Evoked Potentials, N200,Evoked Potentials, N300,Evoked Potentials, N400,Evoked Potentials, P200,Evoked Potentials, P50,Evoked Potentials, P600,N1 Waves,N2 Waves,N200 Evoked Potential,N3 Waves,N300 Evoked Potential,N4 Waves,N400 Evoked Potential,P2 Waves,P200 Evoked Potential,P50 Waves,P600 Evoked Potential,Potential, Event Related,Potential, Event-Related,Potential, Evoked,Potentials, Event Related,Potentials, Evoked,Potentials, N400 Evoked,Related Potential, Event,Related Potentials, Event,Wave, N1,Wave, N2,Wave, N3,Wave, N4,Wave, P2,Wave, P50,Waves, N1,Waves, N2,Waves, N3,Waves, N4,Waves, P2,Waves, P50
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013116 Spinal Cord A cylindrical column of tissue that lies within the vertebral canal. It is composed of WHITE MATTER and GRAY MATTER. Coccygeal Cord,Conus Medullaris,Conus Terminalis,Lumbar Cord,Medulla Spinalis,Myelon,Sacral Cord,Thoracic Cord,Coccygeal Cords,Conus Medullari,Conus Terminali,Cord, Coccygeal,Cord, Lumbar,Cord, Sacral,Cord, Spinal,Cord, Thoracic,Cords, Coccygeal,Cords, Lumbar,Cords, Sacral,Cords, Spinal,Cords, Thoracic,Lumbar Cords,Medulla Spinali,Medullari, Conus,Medullaris, Conus,Myelons,Sacral Cords,Spinal Cords,Spinali, Medulla,Spinalis, Medulla,Terminali, Conus,Terminalis, Conus,Thoracic Cords

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