Differential effects of delta-9-tetrahydrocannabinol and its 11-hydroxy metabolite on sodium current in neuroblastoma cells

Evaluation of Patient Reported Safety and Efficacy of Cannabis From a Survey of Medical Cannabis Patients in Canada

With the medical use of cannabis permitted in Canada since 2001, patients seek to use this botanical drug to treat a range of medical conditions. However, many healthcare practitioners express the need for further scientific evidence around the use of medical cannabis. This real-world evidence study aimed to address the paucity of scientific data by surveying newly registered medical cannabis patients, before beginning medical cannabis treatment, and at one follow up 6 weeks after beginning medical cannabis treatment. The goal was to collect data on efficacy, safety and cannabis product type information to capture the potential impact medical cannabis had on patient-reported quality of life (QOL) and several medical conditions over a 6-week period using validated questionnaires. The 214 participants were mainly male (58%) and 57% of the population was older than 50. The most frequently reported medical conditions were recurrent pain, post-traumatic stress disorder (PTSD), anxiety, sleep disorders [including restless leg syndrome (RLS)], and arthritis and other rheumatic disorders. Here we report that over 60% of our medical cannabis cohort self-reported improvements in their medical conditions. With the use of validated surveys, we found significant improvements in recurrent pain, PTSD, and sleep disorders after 6 weeks of medical cannabis treatment. Our findings from patients who reported arthritis and other rheumatic disorders are complex, showing improvements in pain and global activity sub-scores, but not overall changes in validated survey scores. We also report that patients who stated anxiety as their main medical condition did not experience significant changes in their anxiety after 6 weeks of cannabis treatment, though there were QOL improvements. While these results show that patients find cannabis treatment effective for a broad range of medical conditions, cannabis was not a remedy for all the conditions investigated. Thus, there is a need for future clinical research to support the findings we have reported. Additionally, while real-world evidence has not historically been utilized by regulatory bodies, we suggest changes in public policy surrounding cannabis should occur to reflect patient reported efficacy of cannabis from real-world studies due to the uniqueness of medical cannabis's path to legalization.

Neuromolecular Mechanisms of Cannabis Action

Most of our current understanding of the neuromolecular mechanisms of Cannabis action focusses on two plant cannabinoids, THC and CBD. THC acts primarily through presynaptic CB cannabinoid receptors to regulate neurotransmitter release in the brain, spinal cord and peripheral nerves. CBD action, on the other hand, is probably mediated through multiple molecular targets.

Human Pharmacokinetic Parameters of Orally Administered Δ9-Tetrahydrocannabinol Capsules Are Altered by Fed Versus Fasted Conditions and Sex Differences

Background: There is variability in the reported Δ⁹-tetrahydrocannabinol (THC) and 11-hydroxy-tetrahydrocannabinol (11-OH-THC) pharmacokinetic (PK) and pharmacodynamic (PD) parameters between studies and there is limited investigation into how the presence of food or sex affect these parameters. In this study, we examined the PK and PD parameters of an encapsulated THC extract and its major active metabolite, 11-OH-THC, under different fed states. Methods: The study was a single-dose, randomized, double-blinded, four-way crossover investigation. THC capsules (1 or 2×5 mg) were administered to 28 healthy adults (13 females: 15 males) under a fasted condition or after a high-fat meal. Blood samples were collected and PK parameters were determined through noncompartmental analysis. Adverse events (AEs), cognitive function (through completion of digit symbol substitution tests), blood pressure, and heart rate were also recorded. Results: The presence of high-fat food significantly enhanced time to peak plasma concentration (T _max) and area under the curve (AUC_0-24) for both THC and 11-OH-THC and reduced THC's apparent volume of distribution (V _z/F) and apparent clearance (Cl/F). Females had a significantly greater peak plasma concentration (C _max) compared with males after 5 mg THC in a fasted state. No cardiovascular or cognitive effects and only mild AEs (somnolence, fatigue, and euphoric mood) were reported. Conclusion: These findings may help to inform the guidelines provided by governing health bodies on the effects of cannabis, such as time to onset and duration of action, and aid health care practitioners in their prescribing practices. Furthermore, the doses used in this study are safe to consider for future interventional studies in disease conditions where THC has been shown to have therapeutic efficacy.

Phytocannabinoids as novel therapeutic agents in CNS disorders

The Cannabis sativa herb contains over 100 phytocannabinoid (pCB) compounds and has been used for thousands of years for both recreational and medicinal purposes. In the past two decades, characterisation of the body's endogenous cannabinoid (CB) (endocannabinoid, eCB) system (ECS) has highlighted activation of central CB(1) receptors by the major pCB, Δ(9)-tetrahydrocannabinol (Δ(9)-THC) as the primary mediator of the psychoactive, hyperphagic and some of the potentially therapeutic properties of ingested cannabis. Whilst Δ(9)-THC is the most prevalent and widely studied pCB, it is also the predominant psychotropic component of cannabis, a property that likely limits its widespread therapeutic use as an isolated agent. In this regard, research focus has recently widened to include other pCBs including cannabidiol (CBD), cannabigerol (CBG), Δ(9)tetrahydrocannabivarin (Δ(9)-THCV) and cannabidivarin (CBDV), some of which show potential as therapeutic agents in preclinical models of CNS disease. Moreover, it is becoming evident that these non-Δ(9)-THC pCBs act at a wide range of pharmacological targets, not solely limited to CB receptors. Disorders that could be targeted include epilepsy, neurodegenerative diseases, affective disorders and the central modulation of feeding behaviour. Here, we review pCB effects in preclinical models of CNS disease and, where available, clinical trial data that support therapeutic effects. Such developments may soon yield the first non-Δ(9)-THC pCB-based medicines.

Receptor-independent actions of cannabinoids on cell membranes: Focus on endocannabinoids

Cannabinoids are a structurally diverse group of mostly lipophilic molecules that bind to cannabinoid receptors. In fact, endogenous cannabinoids (endocannabinoids) are a class of signaling lipids consisting of amides and esters of long-chain polyunsaturated fatty acids. They are synthesized from lipid precursors in plasma membranes via Ca(2+) or G-protein-dependent processes and exhibit cannabinoid-like actions by binding to cannabinoid receptors. However, endocannabinoids can produce effects that are not mediated by these receptors. In pharmacologically relevant concentrations, endocannabinoids modulate the functional properties of voltage-gated ion channels including Ca(2+) channels, Na(+) channels, various types of K(+) channels, and ligand-gated ion channels such as serotonin type 3, nicotinic acetylcholine, and glycine receptors. In addition, modulatory effects of endocannabinoids on other ion-transporting membrane proteins such as transient potential receptor-class channels, gap junctions and transporters for neurotransmitters have also been demonstrated. Furthermore, functional properties of G-protein-coupled receptors for different types of neurotransmitters and neuropeptides are altered by direct actions of endocannabinoids. Although the mechanisms of these effects are currently not clear, it is likely that these direct actions of endocannabinoids are due to their lipophilic structures. These findings indicate that additional molecular targets for endocannabinoids exist and that these targets may represent novel sites for cannabinoids to alter either the excitability of the neurons or the response of the neuronal systems. This review focuses on the results of recent studies indicating that beyond their receptor-mediated effects, endocannabinoids alter the functions of ion channels and other integral membrane proteins directly.

Cannabinoid receptor signaling

The cannabinoid receptor family currently includes two types: CB1, characterized in neuronal cells and brain, and CB2, characterized in immune cells and tissues. CB1 and CB2 receptors are members of the superfamily of seven-transmembrane-spanning (7-TM) receptors, having a protein structure defined by an array of seven membrane-spanning helices with intervening intracellular loops and a C-terminal domain that can associate with G proteins. Cannabinoid receptors are associated with G proteins of the Gi/o family (Gi1, 2 and 3, and Go1 and 2). Signal transduction via Gi inhibits adenylyl cyclase in most tissues and cells, although signaling via Gs stimulates adenylyl cyclase in some experimental models. Evidence exists for cannabinoid receptor-mediated Ca2+ fluxes and stimulation of phospholipases A and C. Stimulation of CB1 and CB2 cannabinoid receptors leads to phosphorylation and activation of p42/p44 mitogen-activated protein kinase (MAPK), p38 MAPK and Jun N-terminal kinase (JNK) as signaling pathways to regulate nuclear transcription factors. The CB1 receptor regulates K+ and Ca2+ ion channels, probably via Go. Ion channel regulation serves as an important component of neurotransmission modulation by endogenous cannabinoid compounds released in response to neuronal depolarization. Cannabinoid receptor signaling via G proteins results from interactions with the second, third and fourth intracellular loops of the receptor. Desensitization of signal transduction pathways that couple through the G proteins probably entails phosphorylation of critical amino acid residues on these intracellular surfaces.

Anandamide suppression of Na+ currents in rat dorsal root ganglion neurons

Anandamide, the ethanolamide of arachidonic acid, is an endogenous cannabinoid. It is an agonist at CB1 and CB2 cannabinoid receptors as well as the vanilloid receptor, VR1. It is analgesic in inflammatory and neuropathic pain. Both central and peripheral mechanisms are considered to participate in its analgesia. Primary sensory neurons express Na+ currents that are involved in the pathogenesis of pain. We examined the effect of anandamide on tetrodotoxin-sensitive (TTX-S) and tetrodotoxin-resistant (TTX-R) Na+ currents in rat dorsal root ganglion neurons. Anandamide inhibited both Na+ currents in a concentration-dependent manner. At a membrane potential of -80 mV, the current inhibition was greater in TTX-S than TTX-R currents (K(d); 5.4 microM vs. 38.4 microM). The activation and inactivation became faster in TTX-R current but not in TTX-S current. Anandamide did not alter the activation voltage in either type of current. It, however, produced a hyperpolarizing shift of the steady-state inactivation voltage in both types of currents. The maximum availability at a large negative potential was not reduced by anandamide. Thus, anandamide seems to affect inactivated Na+ channels rather than resting channels. The inhibition of Na+ currents was not reversed by AM 251 (a CB1 antagonist), AM 630 (a CB2 antagonist) or capsazepine (a VR1 antagonist), suggestive of a direct action of anandamide on Na+ channels. The inhibition of Na+ currents in sensory neurons may contribute to the anandamide analgesia.

Dose and behavioral context dependent inhibition of movement and basal ganglia neural activity by ??9-tetrahydrocannabinol during spontaneous and treadmill locomotion tasks in rats

The effects of Delta-9-tetrahydrocannabinole (Delta-9-THC) on locomotor activities and related basal ganglia neural responses were investigated in rats. A multiple-channel, single unit recording method was used to record neuronal activity in the dorsal lateral striatum, the globus pallidus, the subthalamic nucleus, and the substantia nigra pars reticulata simultaneously during spontaneous movement and treadmill locomotion. Delta-9-THC treatment (0.05-2.0 mg/kg, i.p.) dose-dependently decreased spontaneous motor activity and altered walking patterns in treadmill locomotion in that stance time was increased and step number was decreased. In parallel with the behavioral effects, Delta-9-THC treatment inhibited neural activity across all four basal ganglia areas recorded during both motor tests. Further, this inhibition of basal ganglia neural activity was behavioral context-dependent. Greater inhibition was found during resting than during walking periods in the treadmill locomotion test. Delta-9-THC treatment also changed firing patterns in the striatum and globus pallidus. More neurons in these regions discharged in an oscillatory pattern during treadmill walking with Delta-9-THC, and the oscillatory frequency was similar to that of the step cycle. Synchronized firing patterns were found in few basal ganglia neurons in the control condition (approximately 1%). Synchronized firing patterns increased during the treadmill resting phase after Delta-9-THC treatment, but still represented a very small proportion of the total neural population (1.9%). The drug treatment did not change neural responses to the tone cue proceeding treadmill locomotion. This study demonstrates dose-dependent inhibitory effects of cannabinoid injection on motor activity. This effect may be related to the behavioral context-dependent inhibition observed in the basal ganglia system where CB1 receptors are densely distributed.

Pharmacology of cannabinoid CB1 and CB2 receptors

There are at least two types of cannabinoid receptors, CB1 and CB2, both coupled to G-proteins. CB1 receptors are present in the central nervous system and CB1 and CB2 receptors in certain peripheral tissues. The existence of endogenous cannabinoid receptor agonists has also been demonstrated. These discoveries have led to the development of selective cannabinoid CB1 and CB2 receptor ligands. This review focuses on the classification, binding properties, effector systems and distribution of cannabinoid receptors. It also describes the various cannabinoid receptor agonists and antagonists now available and considers the main in vivo and in vitro bioassay methods that are generally used.

Neuronal responses to delta 9-tetrahydrocannabinol in the solitary tract nucleus

The effects of delta 9-tetrahydrocannabinol on single-unit activity in the subpostremal division of the nucleus tractus solitarii were investigated by extracellular recording in rat brain slices. The spontaneous firing rate of 54.8% of the recorded neurons was significantly changed after bath applications of delta 9-tetrahydrocannabinol. Putative nutrition-related neurons responding to a moderate increase in glucose concentration were selectively sensitive to delta 9-tetrahydrocannabinol. The delta 9-tetrahydrocannabinol-sensitive neurons were depressed by clonidine and are therefore likely to be adrenergic or noradrenergic. These observations suggest that some catecholaminergic, glucose-responsive neurons in the subpostremal nucleus tractus solitarii might mediate the influence of cannabinoids on feeding behaviour. Furthermore, most delta 9-tetrahydrocannabinol-sensitive neurons in the nucleus tractus solitarii showed opposite responses to delta 9-tetrahydrocannabinol and the 5-HT3 receptor agonist 1-phenylbiguanide, and might therefore be involved in the nausea-reducing effects of cannabinoids.

Cannabinoids inhibit agonist-stimulated formation of inositol phosphates in rat hippocampal cultures

The effect of cannabinoids on phosphoinositide metabolism stimulated by activation of muscarinic receptors, alpha 1-adrenoceptors or glutamate receptors was examined in rat hippocampal cultures. Carbachol stimulated phosphoinositide turnover by 5.5-fold over basal level, whereas glutamate and norepinephrine stimulated phosphoinositide turnover by 2-fold. Addition of cannabinoids, such as delta 8-tetrahydrocannabinol, delta 9-tetrahydrocannabinol or the psychoinactive cannabidiol inhibited formation of inositol phosphates evoked by carbachol, glutamate or norepinephrine by 55-90%. The cannabinoids alone only slightly inhibited the basal unstimulated formation of inositol phosphates. The inhibitory effect of the cannabinoids was dose-dependent and was achieved within the range of pharmacologically relevant concentrations. IC50 values for delta 8-tetrahydrocannabinol, delta 9-tetrahydrocannabinol and cannabidiol were 9.6 +/- 1.0, 9.7 +/- 0.3 and 7.9 +/- 0.4 microM, respectively. Pretreatment with pertussis toxin (100 ng/ml, 18 h) did not affect the carbachol-induced stimulation of phosphoinositide turnover or its inhibition by the cannabinoids. This suggests that the inhibition by the cannabinoids of the stimulated formation of inositol phosphates is not mediated through a pertussis toxin-sensitive GTP-binding protein nor through the known effect of the cannabinoids on adenylate cyclase inhibition.