An investigation of novel pharmacology of endocannabinoids, phytocannabinoids and related compounds
The research detailed in this thesis consisted of three individual investigations: Firstly, the characterisation of the novel eicosanoid, leukotriene B4 ethanolamide (LTB4 ethanolamide), with leukotriene BLT and vanilliod TRPV1 receptors using rat TRPV1-transfected CHO cells, neonatal rat cultured dorsal root ganglion neurones, guinea-pig lung parenchyma and human neutrophils. LTB4 ethanolamide acts as an antagonist/partial agonist, depending upon receptor expression, at BLT receptors, and as a weak partial agonist at TRPV1 receptors. Secondly, the characterisation of novel compounds at BLT and TRPV1 receptors. These compounds were designed to exhibit antagonism of both these receptors. O-3367and O-3383 act as competitive BLT receptor antagonists with IC50 values of ~ 60 nM and ~ μM, respectively. O-3367 acts as a competitive antagonist at TRPV1 receptors with an IC50 values of ~ μM. Thirdly, the effect of cannabinoids have on human neutrophil migration was investigated. Anamdamide, N-arachidonyl dopamine, virodhamine, CP55940, cannabidiol, (+)-cannabidiol and abnormal-cannabidiol all inhibited N-formylmethyionylleucylphenylalainine (fMLP) – induced neutrophil migration in a concentration-dependent manner. Sphingosine-1 –phosphate, a compound structurally related to anandamide was also capable of inhibiting induced migration, whereas palmitoylethanolamide, 2-arachidonylglycerol, Δ9tetrahydrocannabinol, O-2654, SR141716A, SR144528, capsazepine and AM630 was not. O-2654 induced a concentration-dependent stimulation of neutrophil migration with an EC50 of 16.7 nM. The findings suggest cannabinoids function as anti-inflammatory or immunosuppressive agents, by interfering with chemoattractant-induced directional migration of neutrophils.