PKCepsilon Manipulation Affected One CB1 Agonist More Than Another
Manipulating PKCepsilon changed mouse sensitivity to WIN55,212-2 without producing the same behavioral change for CP55,940. Sharing CB1 activity did not make the agonists interchangeable.
Behavior and binding were examined
The study combined genetic deletion and pharmacological inhibition with animal behavioral testing and brain-membrane binding assays. These were preclinical experiments with synthetic agonists, rather than a study of cannabis patients.
The ligand-specific pattern was central
WIN responses increased after PKCepsilon disruption, and selected repeated-treatment tolerance measures were greater. WIN binding affinity changed, while the comparison inverse-agonist binding result did not show the same difference. The structurally different CP55,940 also lacked the corresponding behavioral sensitivity change.
The proposed explanation had limits
The authors did not fully establish how the kinase altered ligand affinity. A change in binding should not automatically be described as more receptors, stronger signaling through every pathway or greater human impairment. This paper supports testing drug-specific mechanisms. It cannot supply a THC dose conversion, a clinical tolerance biomarker or a prediction that every CB1 agonist will respond similarly to the same molecular intervention.
Related analysis: Cannabis Tolerance Claims: Questions to Ask Before Relying on Expert Testimony.
Primary research
PKCepsilon regulates behavioral sensitivity, binding and tolerance to the CB1 receptor agonist WIN55,212-2. Neuropsychopharmacology : official publication of the American College of Neuropsychopharmacology (2009). DOI: 10.1038/npp.2008.230.
