Effect of acute administration of delta 1-tetrahydrocannabinol on beta-endorphin levels in plasma and brain tissue of the rat

Effects of cannabinoids on neuropeptide Y and β-endorphin expression in the rat hypothalamic arcuate nucleus

The control of appetite and satiety is extremely complex and involves a balance between neurotransmitters and neuropeptides to stimulate and/or inhibit feeding behaviour. The effect of cannabinoids on food intake is well established, but little is known about the mechanism of action underlying their activity. In the present report, the effect of pharmacological manipulation of the cannabinoid receptor on the expression of hypothalamic neuropeptides is investigated. We used an immunohistochemical approach to examine the effect of intracerebroventricular administration of the cannabinoid receptor agonist WIN55,212-2 and the inverse agonist AM251 on neuropeptide Y (NPY) and the β-endorphin (β-end) neuronal hypothalamic systems. Double immunohistochemistry (c-fos/β-end) was used to assess the number of β-end neurons activated by the cannabinoid agonist. The present results showed that 1 μg WIN 55,212-2 increases β-end immunoreactivity within the arcuate nucleus while no significant changes were noted in the NPY-immunoreactive nerve fibres network in comparison to the control group. Injection of 1 μg AM251 decreases both NPY and β-end immunoreactivity within the arcuate nucleus. The number of β-end neurons exhibiting c-fos increased significantly in WIN 55,212-2 compared with the control group. These results suggest that cannabinoids affect the expression of hypothalamic neuropeptides, notably the NPY and β-end systems, which may have implications in the orexigenic action of cannabinoids.

Nabilone for the treatment of pain in fibromyalgia

A randomized, double-blind, placebo-controlled trial was conducted to determine the benefit of nabilone in pain management and quality of life improvement in 40 patients with fibromyalgia. After a baseline assessment, subjects were titrated up on nabilone, from 0.5 mg PO at bedtime to 1 mg BID over 4 weeks or received a corresponding placebo. At the 2- and 4-week visits, the primary outcome measure, visual analog scale (VAS) for pain, and the secondary outcome measures, number of tender points, the average tender point pain threshold, and the Fibromyalgia Impact Questionnaire (FIQ), were evaluated. After a 4-week washout period, subjects returned for reassessment of the outcome measures. There were no significant differences in population demographics between groups at baseline. There were significant decreases in the VAS (-2.04, P < .02), FIQ (-12.07, P < .02), and anxiety (-1.67, P < .02) in the nabilone treated group at 4 weeks. There were no significant improvements in the placebo group. The treatment group experienced more side effects per person at 2 and 4 weeks (1.58, P < .02 and 1.54, P < .05), respectively. Nabilone appears to be a beneficial, well-tolerated treatment option for fibromyalgia patients, with significant benefits in pain relief and functional improvement.

PERSPECTIVE

To our knowledge, this is the first randomized, controlled trial to assess the benefit of nabilone, a synthetic cannabinoid, on pain reduction and quality of life improvement in patients with fibromyalgia. As nabilone improved symptoms and was well-tolerated, it may be a useful adjunct for pain management in fibromyalgia.