DIETIS LAB
  • Main Page
    • About the Lab
  • News
  • Research
    • Research Output
  • Expertise & Equipment
  • People
    • Lab Head
    • Lab members
  • Resources
  • Contact
  • Research Projects
Our Lab presented recent data on morphine's pharmacology
at the 2017 meeting of the 
European Behavioural Pharmacology Society ​(Heraklion, Crete, Greece)
Picture
Click to view & download the poster 
Picture
Abstract
Morphine is the gold-standard for the treatment of chronic or cancer pain in diverse dosing regimens. Nevertheless, morphine’s long-term use is severely limited by its biphasic side-effects on motor behavior (inhibitory or excitatory) and the manifestation of analgesic tolerance (e.g. reduced analgesic efficacy). Despite our increasing knowledge on morphine’s activity, little is known about the role of its dosing to the manifestation of biphasic motor effects and analgesic tolerance. Understanding how morphine’s dosing contributes to behaviour is crucial towards future clinical strategies for reducing morphine’s side-effects and tolerance.
In our study we administered repetitive subcutaneous morphine in rats, using two different regimen groups (Group A: 5 mg/kg/day b.i.d. for 5 days followed by 10mg/kg/day for 11 days & Group B: 10mg/kg/day b.i.d. for 10 days, followed by 20mg/kg/day for 4 days), for 14 days. Animals were observed for their motor/exploratory behaviours (distance travelled, speed, moving-time, rearing, rotation) in an open-field arena of a Multi-Conditioning System with 3D infra-red sensors, prior to and until 180mins after each injection. Antinociception was recorded using a standard tail-flick assay.
We show that animals treated with the low morphine dose developed reduced motor behaviours, which did not desensitize upon repetitive administration, even during the development of antinociceptive tolerance. However, animals treated with a higher morphine dose developed acute depressive behaviours that quickly desensitized to basal levels and progressed to an excitatory phase after 10 days upon antinociceptive tolerance. Rearing behaviour was the only observed behaviour that remained in an inhibitory state irrespective of dosing. The excitatory phase of high-dose morphine dissipated to an inhibitory phase upon introduction of a single double-size dose.
Our results suggest that morphine dosing determines the expression profile of morphine’s behavioural effects and that antinociceptive tolerance is linked to the excitatory phase of morphine’s motor effects. 
Back to Lab News

Visit us

"..I will use treatment to help the sick according to my ability and judgment, but never with a view to injury and wrong-doing. Neither will I administer a poison to anybody when asked to do so, nor will I suggest such a course. (..). But I will keep pure and holy both my life and my art. I will not use the knife, not even, verily, on sufferers from stone but I will give place to such as are craftsmen therein.."                          
​​Hippocratic Oath, 5th cent. BC, Ancient Greece

Connect with us

    Subscribe for Lab news alerts!

    Insert your email here and we will be sending you an alert email whenever a News item is added on our Lab website! In that way, you will always be informed when something important happens in our Lab!
Submit
  • Main Page
    • About the Lab
  • News
  • Research
    • Research Output
  • Expertise & Equipment
  • People
    • Lab Head
    • Lab members
  • Resources
  • Contact
  • Research Projects