A Borderline Withdrawal Comparison Did Not Match Stronger CB2 Pain Findings
An experimental CB2 agonist showed substantial pain-related findings in mice, but one withdrawal comparison was only a statistical trend. Keeping that distinction prevents a positive mechanism study from overstating every outcome.
Cell signaling and mouse behavior were assessed
LY2828360 was characterized in receptor assays and in mice with paclitaxel-related neuropathy. The study included animals lacking CB2 receptors, allowing researchers to test whether selected behavioral effects required that receptor.
Several findings supported CB2 involvement
The abstract reports sustained antiallodynic efficacy in wild-type mice and absence of that efficacy in CB2-knockout mice. Prior treatment and coadministration experiments also showed receptor-dependent effects on morphine tolerance.
The withdrawal comparison was weaker
For one comparison of naloxone-precipitated jumps between treated wild-type and knockout mice, the abstract reported p = 0.055. The authors described it as a trend. It should not be restated as a conventionally significant demonstration that physical dependence was reduced.
The same report notes a prior osteoarthritis clinical trial without efficacy. That human result and the mouse neuropathy result concern different disease settings and should not be forced into one conclusion. Neither the cell-signaling profile nor a favorable mouse endpoint establishes a clinically effective cannabis treatment. The defensible account distinguishes positive receptor-dependent findings, the weaker withdrawal result and the limits of translation.
Related: interpreting cannabis tolerance claims.
Research cited
Lin X; Dhopeshwarkar AS; Huibregtse M; Mackie K; Hohmann AG. Slowly Signaling G Protein-Biased CB2 Cannabinoid Receptor Agonist LY2828360 Suppresses Neuropathic Pain with Sustained Efficacy and Attenuates Morphine Tolerance and Dependence. Molecular pharmacology (2018). doi:10.1124/mol.117.109355. Findings discussed from the study abstract.
