Lobeline Attenuates the Locomotor-Activating Properties of Repeated Morphine Treatment in Rats
Purpose: Lobeline perturbs intra- and extracellular neurotransmitter levels and diminishes the in vitro and in vivo effects of psychostimulants. More recently, lobeline was shown to bind to μ opiate receptors, block the effects of opiate receptor agonists, and decrease heroin self-administration in rats. The present study determined the effect of lobeline on morphine-induced changes in locomotor behavior in rats.
Methods: For 12 consecutive days (Days 1 - 12), male rats were administered lobeline (0.3 or 1 mg/kg) followed by morphine (5 or 10 mg/kg) and locomotor activity was measured. On Day 13, the effect of lobeline on the expression of morphine-induced increases in activity was determined.
Results: With repeated morphine treatment, an increase in locomotor activity was observed. In a dosedependent manner, lobeline decreased the morphine-induced increase in activity. Acute lobeline challenge on Day 13 also attenuated the expression of this morphine-induced increase in activity. Conclusion: These results are consistent with previous work where lobeline blocks the locomotoractivtating properties of psychostimulants, and these findings support an emerging literature suggesting that lobeline produces its behavioral effects through an interaction with μ opiate receptors.
Keywords: Behavior, Morphine, Locomotor activity, Behavioural sensitization, μ Opiate receptors
Submission of a manuscript to this journal is a representation that the manuscript has not been published previously and is not under consideration for publication elsewhere.
All authors named in each manuscript would be required to sign a form (to be supplied by the Editor) so that they may retain their copyright in the article but to assign to us (the Publishers) and its licensees in perpetuity, in all forms, formats and media (whether known or created in the future) to (i) publish, reproduce, distribute, display and store the contribution, (ii) translate the contribution into other languages, create adaptations, reprints, include within collections and create summaries, extracts and/or abstracts of the contribution, (iii) create any other derivative works(s) based on the contribution, (iv) to exploit all subsidiary rights in the contribution, (v) the inclusion of electronic links from the contribution to third party material where-ever it may be located, and (vi) license any thrid party to do any or all of the above.