Jove
Visualize
Contact Us
JoVE
x logofacebook logolinkedin logoyoutube logo
ABOUT JoVE
OverviewLeadershipBlogJoVE Help Center
AUTHORS
Publishing ProcessEditorial BoardScope & PoliciesPeer ReviewFAQSubmit
LIBRARIANS
TestimonialsSubscriptionsAccessResourcesLibrary Advisory BoardFAQ
RESEARCH
JoVE JournalMethods CollectionsJoVE Encyclopedia of ExperimentsArchive
EDUCATION
JoVE CoreJoVE BusinessJoVE Science EducationJoVE Lab ManualFaculty Resource CenterFaculty Site
Terms & Conditions of Use
Privacy Policy
Policies

Related Experiment Videos

Opioid agonists/antagonists in morphine-tolerant squirrel monkeys.

L A Dykstra1, M J Picker, K R Powell

  • 1Department of Psychology, University of North Carolina, Chapel Hill 27599-3270.

Pharmacology, Biochemistry, and Behavior
|July 1, 1990
PubMed
Summary

Chronic morphine administration revealed mu antagonist properties in the (-) isomers of cyclazocine and n-allylnormetazocine. Naloxone also showed increased antagonist effects during this regimen.

Related Concept Videos

You might also read

Related Articles

Articles linked to this work by shared authors, journal, and citation graph.

Sort by
Same author

Obituary: J. David LEander, Ph.D. : (April 8, 1944-November 14, 2014).

Psychopharmacology·2015
Same author

Are you a carrier?

The North American veterinarian·2010
Same author

Advantages of vaccination against bovine brucellosis.

Journal of the American Veterinary Medical Association·2010
Same author

Corticotropin releasing factor-1 receptor antagonist, CP-154,526, blocks the expression of ethanol-induced behavioral sensitization in DBA/2J mice.

Neuroscience·2007
Same author

Involvement of protein kinase A in ethanol-induced locomotor activity and sensitization.

Neuroscience·2006
Same author

The role of CB1 receptors in sweet versus fat reinforcement: effect of CB1 receptor deletion, CB1 receptor antagonism (SR141716A) and CB1 receptor agonism (CP-55940).

Behavioural pharmacology·2005

Area of Science:

  • Pharmacology
  • Neuroscience
  • Behavioral Science

Background:

  • Opioid agonists and antagonists are crucial in pain management and addiction treatment.
  • Understanding mixed-action opioids and their isomers is vital for developing targeted therapies.
  • Chronic morphine use can lead to complex changes in opioid receptor sensitivity.

Purpose of the Study:

  • To investigate the effects of chronic morphine on the dose-effect curves of various mu-opioid ligands.
  • To determine if chronic morphine administration unmasks antagonist properties of mixed-action opioids and their isomers.
  • To characterize the mu antagonist potential of (-)-cyclazocine and (-)-n-allylnormetazocine.

Main Methods:

  • Squirrel monkeys were trained to respond under a fixed-ratio 30 schedule for food.

Related Experiment Videos

  • Dose-effect curves for morphine, naloxone, cyclazocine, n-allylnormetazocine, and pentazocine isomers were generated.
  • These curves were assessed before, during, and after a chronic regimen of 6 mg/kg/day morphine.

    • Main Results:

    • Chronic morphine caused a rightward shift (0.5-1.0 log unit) in its own dose-effect curve, indicating tolerance.
    • Naloxone's dose-effect curve shifted significantly leftward (>3 log units) during chronic morphine.
    • (-)-cyclazocine and (-)-n-allylnormetazocine isomers showed leftward shifts (0.6-1.7 log units), revealing mu antagonist activity.

    Conclusions:

    • Chronic morphine administration can reveal or enhance mu antagonist properties of certain opioid compounds.
    • The (-) isomers of cyclazocine and n-allylnormetazocine exhibit significant mu antagonist effects under chronic morphine exposure.
    • These findings have implications for understanding opioid receptor pharmacology and developing novel opioid-based medications.