Biology subjects

Santiago, M. J.

Publications and source records attributed to Santiago, M. J..

3 recordsLinked to original sources

bioRxiv2019

Absence of entourage: Terpenoids commonly found in Cannabis sativa do not modulate the functional activity of Δ9-THC at human CB1 and CB2 receptors

IntroductionCompounds present in Cannabis sativa such as phytocannabinoids and terpenoids, may act in concert to elicit therapeutic effects. Cannabinoids such as {Delta}9-tetrahydrocannabinol ({Delta}9-THC) directly activate cannabinoid receptor 1 (CB1) and cannabinoid receptor 2 (CB2), however, it is not known if terpenoids present in Cannabis also affect cannabinoid receptor signalling. Therefore, we examined 6 common terpenoids alone, and in combination with cannabinoid receptor agonists, on CB1 and CB2 signalling in vitro.\n\nMaterials and MethodsPotassium channel activity in AtT20 FlpIn cells transfected with human CB1 or CB2 receptors was measured in real-time using FLIPR(R) membrane potential dye in a FlexStation 3 plate reader. Terpenoids were tested individually and in combination for periods up to 30 minutes. Endogenous somatostatin receptors served as a control for direct effects of drugs on potassium channels.\n\nResults-Pinene, {beta}-pinene, {beta}-caryophyllene, linalool, limonene and {beta}-myrcene (up to 30-100 {micro}M) did not change membrane potential in AtT20 cells expressing CB1 or CB2, or affect the response to a maximally effective concentration of the synthetic cannabinoid CP55,940. The presence of individual or a combination of terpenoids did not affect the hyperpolarization produced by {Delta}9-THC (10{micro}M): (CB1: control, 59{+/-}7%; with terpenoids (10 {micro}M each) 55{+/-}4%; CB2: {Delta}9-THC 16{+/-}5%, with terpenoids (10 {micro}M each) 17{+/-}4%). To investigate possible effect on desensitization of CB1 responses, all six terpenoids were added together with {Delta}9-THC and signalling measured continuously over 30 min. Terpenoids did not affect desensitization, after 30 minutes the control hyperpolarization recovered by 63{+/-}6%, in the presence of the terpenoids recovery was 61{+/-}5%.\n\nDiscussionNone of the six of the most common terpenoids in Cannabis directly activated CB1 or CB2, or modulated the signalling of the phytocannabinoid agonist {Delta}9-THC. These results suggest that if a phytocannabinoid-terpenoid entourage effect exists, it is not at the CB1 or CB2 receptor level. It remains possible that terpenoids activate CB1 and CB2 signalling pathways that do not involve potassium channels, however, it seems more likely that they may act at different molecular target(s) in the neuronal circuits important for the behavioural effect of Cannabis.

pharmacology and toxicology↗

bioRxiv2018

Cannabichromene is a cannabinoid CB2 receptor agonist

BACKGROUNDCannabichromene (CBC) is one of the most abundant phytocannabinoids in Cannabis spp. It has modest anti-nociceptive and anti-inflammatory effects and potentiates some effects of {Delta}9-tetrahydrocannabinol (THC) in vivo. How CBC exerts these effects is poorly defined and there is little information about its efficacy at cannabinoid receptors. We sought to determine the functional activity of CBC at CB1 and CB2 receptors.\n\nEXPERIMENTAL APPROACHAtT20 cells stably expressing HA-tagged human CB1 and CB2 receptors were used. Assays of cellular membrane potential and loss of cell surface receptors were performed.\n\nKEY RESULTSCBC activated CB2 but not CB1 receptors to produce a hyperpolarization of AtT20 cells. Activation of CB2 receptors was antagonised by the CB2 antagonist AM630 and sensitive to pertussis toxin. Co-application of CBC reduced activation of CB2 receptors CP55,940, a potent CB1 and CB2 agonist. Continuous CBC application induced loss of cell surface CB2 receptors and desensitisation of the CB2-induced hyperpolarization.\n\nCONCLUSIONS AND IMPLICATIONSCannabichromene is a selective CB2 receptor agonist displaying higher efficacy than THC in hyperpolarising AtT20 cells. CBC may contribute to the potential therapeutic effectiveness of some cannabis preparations, potentially through CB2-mediated modulation of inflammation.

pharmacology and toxicology↗

bioRxiv2018

In vitro determination of the CB1 efficacy of illicit synthetic cannabinoids

BACKGROUND AND PURPOSEThe morbidity and mortality associated with recreational use of synthetic cannabinoid receptor agonists (SCRAs) is a major health concern, and may involve over-activation of CB1 receptors. Thus, we sought to determine the efficacy of 13 SCRAs at CB1 using receptor depletion with the irreversible CB1 antagonist AM6544 followed by fitting the curve with the Black and Leff operational model to calculate efficacy.\n\nEXPERIMENTAL APPROACHReceptor depletion in mouse AtT-20 neuroblastoma cells stably expressing human CB1 was achieved by pre-treatment of cells with AM6544 (10 {micro}M, 60 mins). The CB1-mediated hyperpolarisation of AtT20 cells was measured using membrane potential dye. From data fit to the operational model, the efficacy (tau) and affinity (KA) parameters were obtained for each drug.\n\nKEY RESULTSAM6544 did not affect the potency or maximal effect of native somatostatin receptor-induced hyperpolarisation (Control, pEC50 9.13 {+/-} 0.05, Emax 38 {+/-} 1%; AM6544 treated pEC50 9.18 {+/-} 0.04, Emax 39 {+/-} 0.7%). The tau value of {triangleup}9-THC was 70-fold less than the reference CB-agonist CP55940, and 240-fold less than the highest efficacy SCRA, 5F-MDMB-PICA. Most of the SCRAs had about 50% of the efficacy of CP55940. There was no correlation between the tau and KA values for any SCRA.\n\nCONCLUSION AND IMPLICATIONSAll the SCRA tested showed substantially higher agonist activity at CB1 than {triangleup}9-THC, which may contribute to the adverse effects seen with these drugs but not {triangleup}9-THC, although the mechanisms underlying SCRA toxicity are still poorly defined.

pharmacology and toxicology↗