Naloxone-induced facilitation of C-fiber reflexes is reduced by chronic morphine. 1989

J A Bell
Neuroscience Branch, National Institute on Drug Abuse, Baltimore, MD 21224.

The effects of chronic morphine on endogenous opioid function were examined in feline spinal cord. Naloxone-induced facilitation (disinhibition) of the C-fiber reflex was used as a model to reflect endogenous opioid function. Facilitation was reduced 24 h after withdrawal of chronic morphine (14 days). Acute morphine failed to depress C-fiber reflexes in the abstinent cats, indicating tolerance. Thus, these results demonstrated that, after chronic morphine, spinal endogenous opioid function was reduced due to tolerance.

UI MeSH Term Description Entries
D007262 Infusions, Intravenous The long-term (minutes to hours) administration of a fluid into the vein through venipuncture, either by letting the fluid flow by gravity or by pumping it. Drip Infusions,Intravenous Drip,Intravenous Infusions,Drip Infusion,Drip, Intravenous,Infusion, Drip,Infusion, Intravenous,Infusions, Drip,Intravenous Infusion
D008297 Male Males
D009020 Morphine The principal alkaloid in opium and the prototype opiate analgesic and narcotic. Morphine has widespread effects in the central nervous system and on smooth muscle. Morphine Sulfate,Duramorph,MS Contin,Morphia,Morphine Chloride,Morphine Sulfate (2:1), Anhydrous,Morphine Sulfate (2:1), Pentahydrate,Oramorph SR,SDZ 202-250,SDZ202-250,Chloride, Morphine,Contin, MS,SDZ 202 250,SDZ 202250,SDZ202 250,SDZ202250,Sulfate, Morphine
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
D012018 Reflex An involuntary movement or exercise of function in a part, excited in response to a stimulus applied to the periphery and transmitted to the brain or spinal cord.
D002415 Cats The domestic cat, Felis catus, of the carnivore family FELIDAE, comprising over 30 different breeds. The domestic cat is descended primarily from the wild cat of Africa and extreme southwestern Asia. Though probably present in towns in Palestine as long ago as 7000 years, actual domestication occurred in Egypt about 4000 years ago. (From Walker's Mammals of the World, 6th ed, p801) Felis catus,Felis domesticus,Domestic Cats,Felis domestica,Felis sylvestris catus,Cat,Cat, Domestic,Cats, Domestic,Domestic Cat
D004594 Electrophysiology The study of the generation and behavior of electrical charges in living organisms particularly the nervous system and the effects of electricity on living organisms.
D005260 Female Females
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

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