[Abstract Title]. - Society for Neuroscience

injections of morphine (15 ug) at 90 min intervals significantly decreased the antinociceptive
effect and agonist potency in both the tail-flick (TF) and paw-pressure (PP) tests. Cumulative
dose response curves for morphine performed the following day demonstrated a significant
increase in morphine ED50 value (PP: 31 ug, TF: 29 ug) compared to saline (PP: 5.7 ug, TF: 4.6
ug). In the PP test, co-injection of ultra-low dose (+) naloxone (0.005 ng) with morphine blocked
the decrease in both the morphine-induced antinociception and agonist potency (ED50: 2.6 ug).
Interestingly, this effect was not stereoselective as the (+) isomer of naloxone also blocked both
responses. In the TF, co-administration of (+) naloxone (0.005 ng) also attenuated the decrease in
morphine-induced antinocieption as well as the loss of agonist potency (ED50: 2.1 ug).
However, this stereoisomer did not completely prevent the decline in morphine-induced
antinociception, but significantly prevented the loss of morphine potency (ED50: 2.2 ug). The
results demonstrate that ultra-low dose naloxone blocks morphine analgesic tolerance. This
effect, unlike its classical antagonist action, lacks stereoselctivity and may result from a novel
receptor mechanism.
Disclosures: T.M. Mattioli, None; M. Sutak, None; B. Milne, None; K. Jhamandas,
None; C.M. Cahill, None.
Poster
270. Pain: Opioids and Other Analgesics II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 270.8/HH7
Topic: D.08.r. Opioids and other analgesics
Support: University of Kentucky start-up funds
ACS RSG-00-027-04-CDD and NIDA Drug Supply
Title: Effects of transdermal cannabidiol on experimental arthritis
Authors: *L. ZHANG 1 , F. MA 1 , S. M. ABSHIRE 1 , D. HAMMELL 2 , A. STINCHCOMB 2 , K.
N. WESTLUND 1 ;
1 Dept Physiol, 2 Pharmaceut. Sci., Univ. Kentucky, Lexington, KY
Abstract: Cannabidiol (CBD), a non-psychoactive cannabinoid has been examined for its
therapeutic potential for relief of neuropathic pain, cancer pain and inflammation by others.
Transdermal delivery of CBD allows for a more controlled and sustained drug delivery rate. In
the case of pain control, transdermal delivery would allow for treatment of specific target sites.
In the present study, a transdermal formulation of CBD gel was evaluated using an animal