Biology subjects

Banister, S.

Publications and source records attributed to Banister, S..

4 recordsLinked to original sources

bioRxiv2020

Modulation of Human T-type Calcium Channels by Synthetic Cannabinoid Receptor Agonists in vitro

BACKGROUND AND PURPOSEConsumption of Synthetic Cannabinoid Receptor agonists (SCRAs) is associated with severe adverse reactions including seizures, arrhythmias and death, but the molecular mechanisms surrounding SCRA toxicity are not yet established. These disease-like symptoms are also synonymous with altered T-type calcium channel activity which controls rhythmicity in the heart and brain. This study examined whether SCRAs alter T-type activity and whether this represents a possible mechanism of toxicity. EXPERIMENTAL APPROACHFluorescence-based and electrophysiology assays were used to screen 16 structurally related synthetic cannabinoids for their ability to inhibit human T-type calcium channels expressed in HEK293 cells. The most potent compounds were then further examined using patch clamp electrophysiology. KEY RESULTSMDMB-CHMICA and AMB-CHMINACA potently blocked Cav3.2 with IC50 values of 1.5 and 0.74 M respectively. Current inhibition increased from 47 to 80% and 45 to 87% respectively when the channel was in slow-inactivated state. Both SCRAs had little effect on steady state inactivation, however MDMB-CHMICA significantly shifted the half activation potential by -7mV. Neither drug produced frequency dependent block, in contrast to the phytocannabinoid {Delta}9-THC. CONCLUSIONS and IMPLICATIONSSCRAs are potent agonists of CB1 receptors and can be extremely toxic, but observed toxicity also resembles symptoms associated with altered Cav3.2 activity. Many SCRAs tested were potent modulators of Cav3.2, raising the possibility that SC toxicity may be due in part to Cav3.2 modulation. This potent T-type channel modulation suggests the possibility of SCRAs as a new drug class with potential to treat diseases associated with altered T-type channel activity.

pharmacology and toxicology↗

bioRxiv2019

Differential activation of G protein-mediated signalling by synthetic cannabinoid receptor agonists

Synthetic cannabinoid receptor agonists (SCRAs) are new psychoactive substances associated with acute intoxication and even death. However, the molecular mechanisms through which SCRAs may exert their toxic effects remain unclear - including the potential differential activation of G protein subtypes by CB1, a major target of SCRA. We measured CB1-mediated activation of Gs and Gi/o proteins by SCRAs by examining stimulation (PTX-treated) as well as inhibition (non-PTX treated) of forskolin-induced cAMP accumulation in HEK cells stably expressing CB1. Real-time measurements of stimulation and inhibition of cAMP levels were made using a BRET biosensor. We found that the maximum concentration of SCRAs tested (10 M), increased cAMP levels 12 to 45% above that produced by forskolin alone, while the phytocannabinoid THC did not significantly alter cAMP levels in PTX-treated HEK-CB1 cells. All SCRAs had greater potency to inhibit of forskolin-induced cAMP levels than to stimulate cAMP levels. The rank order of potencies for SCRA stimulation of cAMP (Gs) was PB-22 > 5F-MDMB-PICA > JWH-018 > AB-FUBINACA > XLR-11. By contrast, the potency of SCRAs for inhibition of cAMP (Gi/o) was 5F-MDMB-PICA > AB-FUBINACA > PB-22 > JWH-018 > XLR-11. The different rank order of potency of the SCRAs to stimulate Gs-like signalling compared to Gi/o signalling suggests differences in G protein preference between SCRAs. Understanding the apparent differences among these drugs may contribute to unravelling their complex effects in humans.

pharmacology and toxicology↗

bioRxiv2018

The chemistry and pharmacology of putative synthetic cannabinoid receptor agonist (SCRA) new psychoactive substances (NPS) 5F-PY-PICA, 5F-PY-PINACA, and their analogues

The structural diversity of synthetic cannabinoid receptor agonist (SCRA) new psychoactive substances (NPS) has increased since the first examples were reported a decade ago. 5F-PY-PICA and 5F-PY-PINACA were identified in 2015 as putative SCRA NPS, although nothing is known of their pharmacology. 5F-PY-PICA, 5F-PY-PINACA, and analogues intended to explore structure-activity relationships within this class of SCRAs were synthesized and characterized by nuclear magnetic resonance spectroscopy and liquid chromatography-quadrupole time-of-flight-mass spectrometry. Using competitive binding experiments and fluorescence-based plate reader membrane potential assays, the affinities and activities of all analogues at cannabinoid type 1 and type 2 receptors (CB1 and CB2) were evaluated. All ligands showed minimal affinity for CB1 (pKi < 5), although several demonstrated moderate CB2 binding (pKi = 5.45-6.99). At 10 M none of the compounds produced an effect > 50% of CP55,950 at CB1, while several compounds showed a slightly higher relative efficacy at CB2. Unlike other SCRA NPS, 5F-PYPICA and 5F-PY-PINACA did not produce cannabimimetic effects in mice at doses up to 10 mg/kg.

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↗