Send to

Choose Destination
See comment in PubMed Commons below
Brain Res. 1979 Oct 5;174(2):263-71.

Morphine derivatives with diminished opiate receptor potency show enhanced central excitatory activity.


Central excitatory potency of morphine administered by cerebroventricular infusion in enhanced in derivatives substituted at the 3-position (phenolic group) and/or 6-position (alcoholic group). Morphine-3-glucuronide is several hundred times more potent than morphine in evoking dose-related hyperactive motor behavior which can progress to lethal convulsions. Excitatory potencies in decreasing order are: (1) 3-glucuronide; (2) 3-SO4; (3) 3-OAc, 6-OAc (heroin); (4) 6-OAc; (5) 3-OAc; (6) 3-OH, 6-OH (morphine); (7) 3-OCH3 (codeine); (8) 3-OCH3, 6-OCH3 (thebaine). Levorphanol, lacking a 6-OH group, is devoid of excitatory actions. In this series of substituted morphines, there is an inverse relationship between opiate receptor binding potency and central excitatory potency, but codeine and thebaine behave anomalously. These findings are compatible with the hypothesis that morphine acts upon a species of receptor which mediates behavioral and EEG excitation and is distinct from the recognized opiate receptor mediating sedation and analgesia.

[Indexed for MEDLINE]
PubMed Commons home

PubMed Commons

How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for Elsevier Science
    Loading ...
    Support Center