Medicinal cannabis: is delta9-tetrahydrocannabinol necessary for all its effects?

Cannabis is under clinical investigation to assess its potential for medicinal use, but the question arises as to whether there is any advantage in using cannabis extracts compared with isolated Delta9-trans-tetrahydrocannabinol (Delta9THC), the major psychoactive component. We have compared the effect of a standardized cannabis extract (SCE) with pure Delta9THC, at matched concentrations of Delta9THC, and also with a Delta9THC-free extract (Delta9THC-free SCE), using two cannabinoid-sensitive models, a mouse model of multiple sclerosis (MS), and an in-vitro rat brain slice model of epilepsy. Whilst SCE inhibited spasticity in the mouse model of MS to a comparable level, it caused a more rapid onset of muscle relaxation, and a reduction in the time to maximum effect compared with Delta9THC alone. The Delta9THC-free extract or cannabidiol (CBD) caused no inhibition of spasticity. However, in the in-vitro epilepsy model, in which sustained epileptiform seizures were induced by the muscarinic receptor agonist oxotremorine-M in immature rat piriform cortical brain slices, SCE was a more potent and again more rapidly-acting anticonvulsant than isolated Delta9THC, but in this model, the Delta9THC-free extract also exhibited anticonvulsant activity. Cannabidiol did not inhibit seizures, nor did it modulate the activity of Delta9THC in this model. Therefore, as far as some actions of cannabis were concerned (e.g. antispasticity), Delta9THC was the active constituent, which might be modified by the presence of other components. However, for other effects (e.g. anticonvulsant properties) Delta9THC, although active, might not be necessary for the observed effect. Above all, these results demonstrated that not all of the therapeutic actions of cannabis herb might be due to the Delta9THC content

Investigation of the effects of the novel anticonvulsant compound carisbamate(RWJ-333369) on rat piriform cortical neurones in vitro

Background and purpose: Carisbamate is being developed for adjuvant treatment of partial onset epilepsy. Carisbamate produces anticonvulsant effects in primary generalized, complex partial and absence-type seizure models, and exhibits neuroprotective and antiepileptogenic properties in rodent epilepsy models. Phase IIb clinical trials of carisbamate demonstrated efficacy against partial onset seizures; however, its mechanisms of action remain unknown. Here, we report the effects of carisbamate on membrane properties, evoked and spontaneous synaptic transmission and induced epileptiform discharges in layer II-III neurones in piriform cortical brain slices. Experimental approach: Effects of carisbamate were investigated in rat piriform cortical neurones by using intracellular electrophysiological recordings. Key results: Carisbamate (50–400 mmol·L-1) reversibly decreased amplitude, duration and rise-time of evoked action potentials and inhibited repetitive firing, consistent with use-dependent Na+ channel block; 150–400 mmol·L-1 carisbamate reduced neuronal input resistance, without altering membrane potential. After microelectrode intracellular Cl- loading, carisbamate depolarized cells, an effect reversed by picrotoxin. Carisbamate (100–400 mmol·L-1) also selectively depressed lateral olfactory tract-afferent evoked excitatory synaptic transmission (opposed by picrotoxin), consistent with activation of a presynaptic Cl conductance. Lidocaine (40–320 mmol·L-1) mimicked carisbamate, implying similar modes of action. Carisbamate (300–600 mmol·L-1) had no effect on spontaneous GABAA miniature inhibitory postsynaptic currents and at lower concentrations (50–200 mmol·L-1) inhibited Mg2+-free or 4-aminopyridine-induced seizure-like discharges. Conclusions and implications: Carisbamate blocked evoked action potentials use-dependently, consistent with a primary action on Na+ channels and increased Cl- conductances presynaptically and, under certain conditions, postsynaptically to selectively depress excitatory neurotransmission in piriform cortical layer Ia-afferent terminals.

The double triangular test in practice

The double triangular test was introduced twenty years ago, and the purpose of this paper is to review applications that have been made since then. In fact, take-up of the method was rather slow until the late 1990s, but in recent years several clinical trial reports have been published describing its use in a wide range of therapeutic areas. The core of this paper is a detailed account of five trials that have been published since 2000 in which the method was applied to studies of pancreatic cancer, breast cancer, myocardial infarction, epilepsy and bedsores. Before those accounts are given, the method is described and the history behind its evolution is presented. The future potential of the method for sequential case-control and equivalence trials is also discussed. Copyright © 2004 John Wiley & Sons, Ltd.

Active control comparisons: the ideal trial design

This report describes the concept for a clinical trial that uses carbamazepine as the gold-standard active control for a study of newly diagnosed patients. The authors describe an endpoint including efficacy and tolerability, and a stopping rule that uses a series of interim analyses in order to reach a conclusion as efficiently as possible without sacrificing reliability.

Regression, developmental trajectory and associated problems in disorders in the autism spectrum: the SNAP study

We report rates of regression and associated findings in a population derived group of 255 children aged 9-14 years, participating in a prevalence study of autism spectrum disorders (ASD); 53 with narrowly defined autism, 105 with broader ASD and 97 with non-ASD neurodevelopmental problems, drawn from those with special educational needs within a population of 56,946 children. Language regression was reported in 30% with narrowly defined autism, 8% with broader ASD and less than 3% with developmental problems without ASD. A smaller group of children were identified who underwent a less clear setback. Regression was associated with higher rates of autistic symptoms and a deviation in developmental trajectory. Regression was not associated with epilepsy or gastrointestinal problems.

Loss of language in early development of autism and specific language impairment

Background:  Several authors have highlighted areas of overlap in symptoms and impairment among children with autism spectrum disorder (ASD) and children with specific language impairment (SLI). By contrast, loss of language and broadly defined regression have been reported as relatively specific to autism. We compare the incidence of language loss and language progression of children with autism and SLI. Methods:  We used two complementary studies: the Special Needs and Autism Project (SNAP) and the Manchester Language Study (MLS) involving children with SLI. This yielded a combined sample of 368 children (305 males and 63 females) assessed in late childhood for autism, history of language loss, epilepsy, language abilities and nonverbal IQ. Results:  language loss occurred in just 1% of children with SLI but in 15% of children classified as having autism or autism spectrum disorder. Loss was more common among children with autism rather than milder ASD and is much less frequently reported when language development is delayed. For children who lost language skills before their first phrases, the phrased speech milestone was postponed but long-term language skills were not significantly lower than children with autism but without loss. For the few who experienced language loss after acquiring phrased speech, subsequent cognitive performance is more uncertain. Conclusions:  Language loss is highly specific to ASD. The underlying developmental abnormality may be more prevalent than raw data might suggest, its possible presence being hidden for children whose language development is delayed.

Autobiographical memory and the self in a case of transient epileptic amnesia

Transient epileptic amnesia (TEA) is characterized by deficits in autobiographical memory (AM). One of the functions of AM is to maintain the self, suggesting that the self may undergo changes as a result of memory loss in temporal lobe epilepsy. To examine this, we used a modification of a task used to assess the relationship between self and memory (the IAM task) in a single case, E.B. Despite complaints of AM loss, E.B. had no difficulty in producing a range of self-images (e.g., I am a husband) and collections of self-defining AMs in support of these statements. E.B. produced fewer episodic memories at times of self-formation, but this did not seem to impact on the maintenance of self. The results support recent work suggesting the self may be maintained in the absence of episodic memory. The application of tasks such as that used here will further elucidate AM impairment in temporal lobe epilepsy. (C) 2011 Elsevier Inc. All rights reserved.

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 CB1 receptors by the major pCB, Δ9-tetrahydrocannabinol (Δ9-THC) as the primary mediator of the psychoactive, hyperphagic and some of the potentially therapeutic properties of ingested cannabis. Whilst Δ9-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), Δ9tetrahydrocannabivarin (Δ9-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-Δ9-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-Δ9-THC pCB-based medicines.

Cannabidiol exerts anti-convulsant effects in animal models of temporal lobe and partial seizures

Cannabis sativa has been associated with contradictory effects upon seizure states despite its medicinal use by numerous people with epilepsy. We have recently shown that the phytocannabinoid cannabidiol (CBD) reduces seizure severity and lethality in the well-established in vivo model of pentylenetetrazoleinduced generalised seizures, suggesting that earlier, small-scale clinical trials examining CBD effects in people with epilepsy warrant renewed attention. Here, we report the effects of pure CBD (1, 10 and 100 mg/kg) in two other established rodent seizure models, the acute pilocarpine model of temporal lobe seizure and the penicillin model of partial seizure. Seizure activity was video recorded and scored offline using model-specific seizure severity scales. In the pilocarpine model CBD (all doses) significantly reduced the percentage of animals experiencing the most severe seizures. In the penicillin model, CBD (�10 mg/kg) significantly decreased the percentage mortality as a result of seizures; CBD (all doses) also decreased the percentage of animals experiencing the most severe tonic–clonic seizures. These results extend the anticonvulsant profile of CBD; when combined with a reported absence of psychoactive effects, this evidence strongly supports CBD as a therapeutic candidate for a diverse range of human epilepsies.

Cannabidivarin is anticonvulsant in mouse and rat in vitro and in seizure models

Summary Background and purpose: Phytocannabinoids in Cannabis sativa have diverse pharmacological targets extending beyond cannabinoid receptors and several exert notable anticonvulsant effects. For the first time, we investigated the anticonvulsant profile of the phytocannabinoid cannabidivarin (CBDV) in vitro and in in vivo seizure models. Experimental approach: The effect of CBDV (1-100μM) on epileptiform local field potentials (LFPs) induced in rat hippocampal brain slices by 4-AP application or Mg2+-free conditions was assessed by in vitro multi-electrode array recordings. Additionally, the anticonvulsant profile of CBDV (50-200 mg kg-1) in vivo was investigated in four rodent seizure models: maximal electroshock (mES) and audiogenic seizures in mice, and pentylenetetrazole (PTZ) and pilocarpine-induced seizures in rat. CBDV effects in combination with commonly-used antiepileptic drugs were investigated in rat seizures. Finally, the motor side effect profile of CBDV was investigated using static beam and gripstrength assays. Key results: CDBV significantly attenuated status epilepticus-like epileptiform LFPs induced by 4-AP and Mg2+-free conditions. CBDV had significant anticonvulsant effects in mES (≥100 mg kg-1), audiogenic (≥50 mg kg-1) and PTZ-induced seizures (≥100 mg kg-1). CBDV alone had no effect against pilocarpine-induced seizures, but significantly attenuated these seizures when administered with valproate or phenobarbital at 200 mg kg-1 CBDV. CBDV had no effect on motor function. Conclusions and Implications: These results indicate that CBDV is an effective anticonvulsant across a broad range of seizure models, does not significantly affect normal motor function and therefore merits further investigation in chronic epilepsy models to justify human trials.

The anti-epileptic drug Valproic Acid (VPA) inhibits steroidogenesis in bovine theca and granulosa cells in vitro

Valproic acid (VPA) is used widely to treat epilepsy and bipolar disorder. Women undergoing VPA treatment reportedly have an increased incidence of polycystic ovarian syndrome (PCOS)-like symptoms including hyperandrogenism and oligo- or amenorrhoea. To investigate potential direct effects of VPA on ovarian steroidogenesis we used primary bovine theca (TC) and granulosa (GC) cells maintained under conditions that preserve their 'follicular' phenotype. Effects of VPA (7.8-500 µg/ml) on TC were tested with/without LH. Effects of VPA on GC were tested with/without FSH or IGF analogue. VPA reduced (P<0.0001) both basal (70% suppression; IC(50) 67±10 µg/ml) and LH-induced (93% suppression; IC(50) 58±10 µg/ml) androstenedione secretion by TC. VPA reduced CYP17A1 mRNA abundance (>99% decrease; P<0.0001) with lesser effects on LHR, STAR, CYP11A1 and HSD3B1 mRNA (<90% decrease; P<0.05). VPA only reduced TC progesterone secretion induced by the highest (luteinizing) LH dose tested; TC number was unaffected by VPA. At higher concentrations (125-500 µg/ml) VPA inhibited basal, FSH- and IGF-stimulated estradiol secretion (P<0.0001) by GC without affecting progesterone secretion or cell number. VPA reversed FSH-induced upregulation of CYP19A1 and HSD17B1 mRNA abundance (P<0.001). The potent histone deacetylase (HDAC) inhibitors trichostatin A and scriptaid also suppressed TC androstenedione secretion and granulosal cell oestrogen secretion suggesting that the action of VPA reflects its HDAC inhibitory properties. In conclusion, these findings refute the hypothesis that VPA has a direct stimulatory action on TC androgen output. On the contrary, VPA inhibits both LH-dependent androgen production and FSH/IGF-dependent estradiol production in this in vitro bovine model, likely by inhibition of HDAC.

Cannabidivarin-rich cannabis extracts are anticonvulsant in mouse and rat via a CB 1 receptor-independent mechanism

BACKGROUND AND PURPOSE Epilepsy is the most prevalent neurological disease and is characterized by recurrent seizures. Here, we investigate (i) the anticonvulsant profiles of cannabis-derived botanical drug substances (BDSs) rich in cannabidivarin (CBDV) and containing cannabidiol (CBD) in acute in vivo seizure models and (ii) the binding of CBDV BDSs and their components at cannabinoid CB 1 receptors. EXPERIMENTAL APPROACH The anticonvulsant profiles of two CBDV BDSs (50–422 mg·kg −1 ) were evaluated in three animal models of acute seizure. Purified CBDV and CBD were also evaluated in an isobolographic study to evaluate potential pharmacological interactions. CBDV BDS effects on motor function were also investigated using static beam and grip strength assays. Binding of CBDV BDSs to cannabinoid CB 1 receptors was evaluated using displacement binding assays. KEY RESULTS CBDV BDSs exerted significant anticonvulsant effects in the pentylenetetrazole (≥100 mg·kg −1 ) and audiogenic seizure models (≥87 mg·kg −1 ), and suppressed pilocarpine-induced convulsions (≥100 mg·kg −1 ). The isobolographic study revealed that the anticonvulsant effects of purified CBDV and CBD were linearly additive when co-administered. Some motor effects of CBDV BDSs were observed on static beam performance; no effects on grip strength were found. The Δ 9 -tetrahydrocannabinol and Δ 9 -tetrahydrocannabivarin content of CBDV BDS accounted for its greater affinity for CB 1 cannabinoid receptors than purified CBDV. CONCLUSIONS AND IMPLICATIONS CBDV BDSs exerted significant anticonvulsant effects in three models of seizure that were not mediated by the CB 1 cannabinoid receptor and were of comparable efficacy with purified CBDV. These findings strongly support the further clinical development of CBDV BDSs for the treatment of epilepsy.

Nonpsychotropic plant cannabinoids, cannabidivarin (CBDV) and cannabidiol (CBD), activate and desensitize transient receptor potential vanilloid 1 (TRPV1) channels in vitro: potential for the treatment of neuronal hyperexcitability

Epilepsy is the most common neurological disorder, with over 50 million people worldwide affected. Recent evidence suggests that the transient receptor potential cation channel subfamily V member 1 (TRPV1) may contribute to the onset and progression of some forms of epilepsy. Since the two nonpsychotropic cannabinoids cannabidivarin (CBDV) and cannabidiol (CBD) exert anticonvulsant activity in vivo and produce TRPV1-mediated intracellular calcium elevation in vitro, we evaluated the effects of these two compounds on TRPV1 channel activation and desensitization and in an in vitro model of epileptiform activity. Patch clamp analysis in transfected HEK293 cells demonstrated that CBD and CBDV dose-dependently activate and rapidly desensitize TRPV1, as well as TRP channels of subfamily V type 2 (TRPV2) and subfamily A type 1 (TRPA1). TRPV1 and TRPV2 transcripts were shown to be expressed in rat hippocampal tissue. When tested on epileptiform neuronal spike activity in hippocampal brain slices exposed to a Mg2+-free solution using multielectrode arrays (MEAs), CBDV reduced both epileptiform burst amplitude and duration. The prototypical TRPV1 agonist, capsaicin, produced similar, although not identical effects. Capsaicin, but not CBDV, effects on burst amplitude were reversed by IRTX, a selective TRPV1 antagonist. These data suggest that CBDV antiepileptiform effects in the Mg2+-free model are not uniquely mediated via activation of TRPV1. However, TRPV1 was strongly phosphorylated (and hence likely sensitized) in Mg2+-free solution-treated hippocampal tissue, and both capsaicin and CBDV caused TRPV1 dephosphorylation, consistent with TRPV1 desensitization. We propose that CBDV effects on TRP channels should be studied further in different in vitro and in vivo models of epilepsy.

Effective interventions: 25 years outside the mainstream

25 years ago when the Durham conferences were in full swing, I presented results of investigations on language and behaviour in autism. I tentatively proposed that early language in autism might tell us about the cognitive skills of people with ASD and the behaviour might lead to greater understanding of which brain systems might be affected. In this presentation, I will update these topics and present a summary of other work I have been involved with in attempting to improve the lives of people with autism and their families. Data on three people with autism at the early stages of speech development showed an unusual pattern of learning colour and number names early. One possibility was that this skill represented a sign of weak central coherence – they only attended to one dimension. Colleagues of mine were equally puzzled so we tried to find out if my results could be replicated – they were not (see Schafer, Williams & Smith, 2014). Instead we found this pattern was also seen in Down Syndrome, but that early vocabulary in autism was associated with low Colorado Meaningfulness at least in comprehension. The Colorado Meaningfulness of a word is a measure of how many words can be associated with it and often involve extensive use of context. Our data suggest that the number of contexts in which a particular word can appear has a role in determining vocabulary in ASD which is consistent with the weak central coherence theory of autism. In the course of this work I also came across a group of young people with autism who appeared to have a written vocabulary but not a spoken one. It seems possible that print might be a medium of communication when speech is not. Repetitive behaviour in autism remains a mystery. We can use functional analysis to determine why the behaviour occurs, but a worryingly large percentage of behaviours are described as being internally driven or sensory reinforced. What does that mean in terms of brain activity – could it be system analogous to epilepsy, where brain activity becomes inappropriately synchronised? At the moment I cannot claim to have solved this problem, but if sensation is a driver then sensory interventions should make a difference. Data from a recent study will be presented to suggest that for some individuals this is the case. Social behaviour remains the key however, and it remains to be seen whether it is possible for social behaviour to be aided. One route that has potential is direct teaching of skills through drama and working with others who do not have social difficulties of the same type. The picture is complicated by changes in social skills with age and experience, but the failure of people with ASD to interact when in settings of social contact is little researched.

Coupling between gamma-band power and cerebral blood volume during recurrent acute neocortical seizures

Characterization of neural and hemodynamic biomarkers of epileptic activity that can be measured using noninvasive techniques is fundamental to the accurate identification of the epileptogenic zone (EZ) in the clinical setting. Recently, oscillations at gamma-band frequencies and above (N30 Hz) have been suggested to provide valuable localizing information of the EZ and track cortical activation associated with epileptogenic processes. Although a tight coupling between gamma-band activity and hemodynamic-based signals has been consistently demonstrated in non-pathological conditions, very little is known about whether such a relationship is maintained in epilepsy and the laminar etiology of these signals. Confirmation of this relationship may elucidate the underpinnings of perfusion-based signals in epilepsy and the potential value of localizing the EZ using hemodynamic correlates of pathological rhythms. Here, we use concurrent multi-depth electrophysiology and 2- dimensional optical imaging spectroscopy to examine the coupling between multi-band neural activity and cerebral blood volume (CBV) during recurrent acute focal neocortical seizures in the urethane-anesthetized rat. We show a powerful correlation between gamma-band power (25–90 Hz) and CBV across cortical laminae, in particular layer 5, and a close association between gamma measures and multi-unit activity (MUA). Our findings provide insights into the laminar electrophysiological basis of perfusion-based imaging signals in the epileptic state and may have implications for further research using non-invasive multi-modal techniques to localize epileptogenic tissue