Haloperidol, but not clozapine, produces dramatic catalepsy in delta9-THC-treated rats: possible clinical implications

Cannabinoids in the management of behavioral, psychological, and motor symptoms of neurocognitive disorders: a mixed studies systematic review

Aim

We undertook this systematic review to determine the efficacy and safety of cannabis-based medicine as a treatment for behavioral, psychological, and motor symptoms associated with neurocognitive disorders.

Methods

We conducted a PRISMA-guided systematic review to identify studies using cannabis-based medicine to treat behavioral, psychological, and motor symptoms among individuals with Alzheimer's disease (AD) dementia, Parkinson’s disease (PD), and Huntington’s disease (HD). We considered English-language articles providing original data on three or more participants, regardless of design.

Findings

We identified 25 studies spanning 1991 to 2021 comprised of 14 controlled trials, 5 pilot studies, 5 observational studies, and 1 case series. In most cases, the cannabinoids tested were dronabinol, whole cannabis, and cannabidiol, and the diagnoses included AD (n = 11), PD (n = 11), and HD (n = 3). Primary outcomes were motor symptoms (e.g., dyskinesia), sleep disturbance, cognition, balance, body weight, and the occurrence of treatment-emergent adverse events.

Conclusions

A narrative summary of the findings from the limited number of studies in the area highlights an apparent association between cannabidiol-based products and relief from motor symptoms in HD and PD and an apparent association between synthetic cannabinoids and relief from behavioral and psychological symptoms of dementia across AD, PD, and HD. These preliminary conclusions could guide using plant-based versus synthetic cannabinoids as safe, alternative treatments for managing neuropsychiatric symptoms in neurocognitive vulnerable patient populations.

Vortioxetine ameliorates motor and cognitive impairments in the rotenone-induced Parkinson's disease via targeting TLR-2 mediated neuroinflammation

Parkinson's disease (PD) is characterized by motor and non-motor symptoms associated with dopaminergic and non-dopaminergic injury. Vortioxetine is a multimodal serotonergic antidepressant with potential procognitive effects. This study aimed to explore the effects of vortioxetine on motor functions, spatial learning and memory, and depression-like behavior in the rotenone-induced rat model of PD. Male Sprague-Dawley rats were daily administered with the rotenone (2 mg·kg^-1, s.c.) and/or vortioxetine (10 mg·kg^-1, s.c.) for 28 days. Motor functions (rotarod, catalepsy, open-field), depression-like behaviors (sucrose preference test), anxiety (elevated plus maze), and spatial learning and memory abilities (novel object recognition and Morris water maze) were evaluated in behavioral tests. Then immunohistochemical, neurochemical, and biochemical analysis on specific brain areas were performed. Vortioxetine treatment markedly reduced rotenone-induced neurodegeneration, improved motor and cognitive dysfunction, decreased depression-like behaviors without affecting anxiety-like parameters. Vortioxetine also restored the impaired inflammatory response and affected neurotransmitter levels in brain tissues. Interestingly, vortioxetine was thought to trigger a sort of dysfunction in basal ganglia as evidenced by increased Toll-like receptor-2 (TLR-2) and decreased TH immunoreactivity only in substantia nigra tissue of PD rats compared to the control group. The present study indicates that vortioxetine has beneficial effects on motor dysfunction as well as cognitive impairment associated with neurodegeneration in the rotenone-induced PD model. Possible mechanisms underlying these beneficial effects cover TLR-2 inhibition and neurochemical restoration of vortioxetine.

Oral quetiapine treatment results in time-dependent alterations of recognition memory and brain-derived neurotrophic factor-related signaling molecules in the hippocampus of rats

Antipsychotic drugs (APDs) have a variety of important therapeutic applications for neuropsychiatric disorders. However, they are routinely prescribed off-label across all age categories, a controversial practice given their potential for producing metabolic and extrapyramidal side effects. Evidence also suggests that chronic treatment with some APDs may lead to impairments in cognition and decreases in brain volume, although these findings are controversial. The purpose of the studies described here was to evaluate one of the most commonly prescribed APDs, quetiapine, for chronic effects on recognition memory, brain-derived neurotrophic factor (BDNF), its precursor proBDNF, as well as relevant downstream signaling molecules that are known to influence neuronal plasticity and cognition. Multiple cohorts of adult rats were treated with quetiapine (25.0 mg/kg/day) for 30 or 90 days in their drinking water then evaluated for drug effects on motor function in a catalepsy assessment, recognition memory in a spontaneous novel object recognition (NOR) task, and BDNF-related signaling molecules in the post mortem hippocampus via Western Blot. The results indicated that oral quetiapine at a dose that did not induce catalepsy, led to time-dependent impairments in NOR performance, increases in the proBDNF/BDNF ratio, and decreases in Akt and CREB phosphorylation in the hippocampus. These results indicate that chronic treatment with quetiapine has the potential to adversely affect recognition memory and neurotrophin-related signaling molecules that support synaptic plasticity and cognitive function. Given the widespread use this APD across multiple conditions and patient populations, such long-term effects observed in animals should be considered.

Chronic oral treatment with risperidone impairs recognition memory and alters brain-derived neurotrophic factor and related signaling molecules in rats

Antipsychotic drugs (APDs) are essential for the treatment of schizophrenia and other neuropsychiatric illnesses such as bipolar disease. However, they are also extensively prescribed off-label for many other conditions, a practice that is controversial given their potential for long-term side effects. There is clinical and preclinical evidence that chronic treatment with some APDs may lead to impairments in cognition and decreases in brain volume, although the molecular mechanisms of these effects are unknown. The purpose of the rodent studies described here was to evaluate a commonly prescribed APD, risperidone, for chronic effects on recognition memory, brain-derived neurotrophic factor (BDNF), its precursor proBDNF, as well as relevant downstream signaling molecules that are known to influence neuronal plasticity and cognition. Multiple cohorts of adult rats were treated with risperidone (2.5 mg/kg/day) or vehicle (dilute acetic acid solution) in their drinking water for 30 or 90 days. Subjects were then evaluated for drug effects on recognition memory in a spontaneous novel object recognition task and protein levels of BDNF-related signaling molecules in the hippocampus and prefrontal cortex. The results indicated that depending on the treatment period, a therapeutically relevant daily dose of risperidone impaired recognition memory and increased the proBDNF/BDNF ratio in the hippocampus and prefrontal cortex. Risperidone treatment also led to a decrease in Akt and CREB phosphorylation in the prefrontal cortex. These results indicate that chronic treatment with a commonly prescribed APD, risperidone, has the potential to adversely affect recognition memory and neurotrophin-related signaling molecules that support synaptic plasticity and cognitive function.

Effects of haloperidol on the delta-9-tetrahydrocannabinol response in humans: a responder analysis

RATIONALE

Δ-9-Tetrahydrocannabinol (Δ-9-THC) produces psychotomimetic effects in humans. However, the role of dopamine signaling in producing such effects is unclear. We hypothesized that dopaminergic antagonism would reduce the psychotomimetic effect of Δ-9-THC.

OBJECTIVE

The objective of this study was to evaluate whether pre-treatment with haloperidol would alter the psychotomimetic and perceptual-altering effects of Δ-9-THC, measured by the Positive and Negative Syndrome Scale for Schizophrenia (PANSS) and the Clinician-Administered Dissociative Symptom Scale (CADSS) in humans.

METHODS

In a two-test-day double-blind study, 28 healthy individuals were administered with active (0.057 mg/kg) or placebo oral haloperidol, followed 90 and 215 min later by intravenous administration of active (0.0286 mg/kg) Δ-9-THC and placebo, respectively. This secondary analysis was conducted because of the observation in other studies and in our data that a significant proportion of individuals may not have an adequate response to THC (floor effect), thus limiting the ability to test an interaction. Therefore, this analysis was performed including only responders to THC (n = 10), defined as individuals who had an increase of at least one point on the PANSS positive scale, consistent with prior human laboratory studies.

RESULTS

In the 10 responders, Δ-9-THC-induced increases in PANSS positive scores were significantly lower in the haloperidol condition (1.1 + 0.35) compared with the placebo condition (2.9 + 0.92).

CONCLUSION

This responder analysis showed that haloperidol did reduce the psychotomimetic effect of Δ-9-THC, supporting the hypothesis that dopaminergic signaling may participate in the psychosis-like effects of cannabinoids.

Role of vasopressin V1a receptor in ∆9-tetrahydrocannabinol-induced cataleptic immobilization in mice

RATIONALE

Cannabis is a widely used illicit substance. ∆⁹-tetrahydrocannabinol (THC), the major psychoactive component of cannabis, is known to cause catalepsy in rodents. Recent studies have shown that vasopressin V1a and V1b receptors are widely distributed in the central nervous system and are capable of influencing a wide variety of brain functions such as social behavior, emotionality, and learning and memory.

OBJECTIVES

The present study was designed to examine the possible involvement of V1a and V1b receptors in THC-induced catalepsy-like immobilization.

METHODS

The induction of catalepsy following treatment with THC (10 mg/kg, i.p.) or haloperidol (1 mg/kg, i.p.) was evaluated in wild-type (WT), V1a receptor knockout (V1aRKO), and V1b receptor knockout (V1bRKO) mice. The effect of treatment with the selective 5-hydroxytryptamine_1A receptor antagonist WAY100635 (0.1 mg/kg, i.p.) on THC-induced catalepsy was also evaluated in V1aRKO mice. Moreover, the effects of the V1a receptor antagonist VMAX-357 and the V1b receptor antagonist ORG-52186 on THC-induced catalepsy were evaluated in ddY mice.

RESULTS

THC and haloperidol markedly caused catalepsy in V1bRKO mice as well as in WT mice. However, V1aRKO mice exhibited a reduction in catalepsy induced by THC but not by haloperidol. WAY100635 dramatically enhanced THC-induced catalepsy in V1aRKO mice. Although VMAX-357 (10 mg/kg, p.o.) but not ORG-52186 significantly attenuated THC-induced catalepsy, it had no significant effect on the enhancement of THC-induced catalepsy by WAY100635 in ddY mice.

CONCLUSIONS

These findings suggest that V1a receptor regulates THC-induced catalepsy-like immobilization.

CB1 cannabinoid receptor-mediated anandamide signaling mechanisms of the inferior colliculus modulate the haloperidol-induced catalepsy

The inferior colliculus (IC), a midbrain structure that processes acoustic information of aversive nature, is distinguished from other auditory nuclei in the brainstem by its connections with structures of the motor system. Previous evidence relating the IC to motor behavior shows that glutamatergic and GABAergic mechanisms in the IC exert influence on systemic haloperidol-induced catalepsy. There is substantial evidence supporting a role played by the endocannabinoid system as a modulator of the glutamatergic neurotransmission, as well as the dopaminergic activity in the basal nuclei and therefore it may be considered as a potential pharmacological target for the treatment of movement disorders. The present study evaluated if the endocannabinoid system in the IC plays a role in the elaboration of systemic haloperidol-induced catalepsy. Male Wistar rats received intracollicular microinjection of either the endogenous cannabinoid anandamide (AEA) at different concentrations (5, 50 or 100pmol/0.2μl), the CB₁ cannabinoid receptor antagonist AM251 at 50, 100 or 200pmol/0.2μl or vehicle, followed by intraperitoneal (IP) administration of either haloperidol at 0.5 or 1mg/kg or physiological saline. Systemic injection of haloperidol at both doses (0.5 or 1mg/kg, IP) produced a cataleptic state, compared to vehicle/physiological saline-treated group, lasting 30 and 50min after systemic administration of the dopaminergic receptors non-selective antagonist. The midbrain microinjection of AEA at 50pmol/0.2μl increased the latency for stepping down from the horizontal bar after systemic administration of haloperidol. Moreover, the intracollicular administration of AEA at 50pmol/0.2μl was able to increase the duration of catalepsy as compared to AEA at 100pmol/0.2-μl-treated group. Intracollicular pretreatment with AM251 at the intermediate concentration (100pmol/0.2μl) was able to decrease the duration of catalepsy after systemic administration of haloperidol. However, neither the intracollicular microinjection of AM251 at the lowest (50pmol/0.2μl) nor at the highest (200pmol/0.2μl) concentration was able to block the systemic haloperidol-induced catalepsy. Furthermore, the intracollicular administration of AM251 at 100pmol/0.2μl was able to decrease the duration of catalepsy as compared to AM251 at 50pmol/0.2μl- and AM251 at 200pmol/0.2-μl-treated group. The latency for stepping down from the horizontal bar - induced by haloperidol administration - was decreased when microinjection of AEA at 50pmol/0.2μl was preceded with blockade of CB1 receptor with AM251 (100pmol/0.2μl). Our results strengthen the involvement of CB1-signaled endocannabinoid mechanisms of the IC in the neuromodulation of catalepsy induced by systemic administration of the dopaminergic receptors non-selective antagonist haloperidol.

Pharmacological characteristics of zolpidem-induced catalepsy in the rat

Zolpidem is a non-benzodiazepine hypnotic drug acting preferentially at α1-containing GABAA receptors expressed in various parts of the brain, including the basal ganglia. The aim of the present study was to provide preliminary characteristics of zolpidem-induced catalepsy in Wistar rats. Zolpidem (2.5-10.0mg/kg), but not diazepam and midazolam, produced dose-dependent cataleptic responses in the bar test, which were similar to those produced by a reference antipsychotic drug, haloperidol. Zolpidem-induced catalepsy was abolished by a benzodiazepine site antagonist, flumazenil (5.0mg/kg), D2/3 receptor agonist, quinpirole (1.0mg/kg), and a non-competitive NMDA receptor antagonist, MK-801 (0.1mg/kg), but not by a non-selective opioid receptor antagonist, naltrexone (3.0mg/kg). The present results indicate that systemic injections of zolpidem may produce short-lasting, neuroleptic-like catalepsy in the rat.

Cannabidiol attenuates catalepsy induced by distinct pharmacological mechanisms via 5-HT1A receptor activation in mice

Cannabidiol (CBD) is a non-psychotomimetic compound from Cannabis sativa plant that produces antipsychotic effects in rodents and humans. It also reverses L-dopa-induced psychotic symptoms and improves motor function in Parkinson's patients. This latter effect raised the possibility that CBD could have beneficial effects on motor related striatal disorders. To investigate this possibility we evaluated if CBD would prevent catalepsy induced by drugs with distinct pharmacological mechanisms. The catalepsy test is largely used to investigate impairments of motor function caused by interference on striatal function. Male Swiss mice received acute pretreatment with CBD (5, 15, 30 or 60mg/kg, ip) 30min prior to the D2 receptor antagonist haloperidol (0.6mg/kg), the non-selective nitric oxide synthase (NOS) inhibitor L-nitro-N-arginine (L-NOARG, 80mg/kg) or the CB1 receptor agonist WIN55,212-2 (5mg/kg). The mice were tested 1, 2 or 4h after haloperidol, L-NOARG or WIN55,212-2 injection. These drugs significantly increased catalepsy time and this effect was attenuated dose-dependently by CBD. CBD, by itself, did not induce catalepsy. In a second set of experiments the mechanism of CBD effects was investigated. Thirty minutes before CBD (30mg/kg) the animals received the 5-HT1A receptor antagonist WAY100635 (0.1mg/kg). The anticataleptic effect of CBD was prevented by WAY100635. These findings indicate that CBD can attenuate catalepsy caused by different mechanisms (D2 blockade, NOS inhibition and CB1 agonism) via 5-HT1A receptor activation, suggesting that it could be useful in the treatment of striatal disorders.

Targeting the endocannabinoid system with cannabinoid receptor agonists: pharmacological strategies and therapeutic possibilities

Human tissues express cannabinoid CB(1) and CB(2) receptors that can be activated by endogenously released 'endocannabinoids' or exogenously administered compounds in a manner that reduces the symptoms or opposes the underlying causes of several disorders in need of effective therapy. Three medicines that activate cannabinoid CB(1)/CB(2) receptors are now in the clinic: Cesamet (nabilone), Marinol (dronabinol; Δ(9)-tetrahydrocannabinol (Δ(9)-THC)) and Sativex (Δ(9)-THC with cannabidiol). These can be prescribed for the amelioration of chemotherapy-induced nausea and vomiting (Cesamet and Marinol), stimulation of appetite (Marinol) and symptomatic relief of cancer pain and/or management of neuropathic pain and spasticity in adults with multiple sclerosis (Sativex). This review mentions several possible additional therapeutic targets for cannabinoid receptor agonists. These include other kinds of pain, epilepsy, anxiety, depression, Parkinson's and Huntington's diseases, amyotrophic lateral sclerosis, stroke, cancer, drug dependence, glaucoma, autoimmune uveitis, osteoporosis, sepsis, and hepatic, renal, intestinal and cardiovascular disorders. It also describes potential strategies for improving the efficacy and/or benefit-to-risk ratio of these agonists in the clinic. These are strategies that involve (i) targeting cannabinoid receptors located outside the blood-brain barrier, (ii) targeting cannabinoid receptors expressed by a particular tissue, (iii) targeting upregulated cannabinoid receptors, (iv) selectively targeting cannabinoid CB(2) receptors, and/or (v) adjunctive 'multi-targeting'.

Gaafar A. Effects of Cannabis sativa extract on haloperidol-induced catalepsy and oxidative stress in the mice

Haloperidol is a classic antipsychotic drug known for its propensity to cause extrapyramidal symptoms due to blockade of dopamine D2 receptors in the striatum. Interest in medicinal uses of cannabis is growing. Cannabis sativa has been suggested as a possible adjunctive in treatment of Parkinson's disease. The present study aimed to investigate the effect of repeated administration of an extract of Cannabis sativa on catalepsy and brain oxidative stress induced by haloperidol administration in mice. Cannabis extract was given by subcutaneous route at 5, 10 or 20 mg/kg (expressed as Δ(9)-tetrahydrocannabinol) once daily for 18 days and the effect on haloperidol (1 mg/kg, i.p.)-induced catalepsy was examined at selected time intervals using the bar test. Mice were euthanized 18 days after starting cannabis injection when biochemical assays were carried out. Malondialdehyde (MDA), reduced glutathione (GSH) and nitric oxide (the concentrations of nitrite/nitrate) were determined in brain and liver. In saline-treated mice, no catalepsy was observed at doses of cannabis up to 20 mg/kg. Mice treated with haloperidol at the dose of 1 mg/kg, exhibited significant cataleptic response. Mice treated with cannabis and haloperidol showed significant decrease in catalepsy duration, compared with the haloperidol only treated group. This decrease in catalepsy duration was evident on days 1-12 after starting cannabis injection. Later the effect of cannabis was not apparent. The administration of only cannabis (10 or 20 mg/kg) decreased brain MDA by 17.5 and 21.8 %, respectively. The level of nitric oxide decreased by 18 % after cannabis at 20 mg/kg. Glucose in brain decreased by 20.1 % after 20 mg/kg of cannabis extract. The administration of only haloperidol increased MDA (22.2 %), decreased GSH (25.7 %) and increased brain nitric oxide by 44.1 %. The administration of cannabis (10 or 20 mg/kg) to haloperidol-treated mice resulted in a significant decrease in brain MDA and nitric oxide as well as a significant increase in GSH and glucose compared with the haloperidol-control group. Cannabis had no significant effects on liver MDA, GSH, nitric oxide in saline or haloperidol-treated mice. It is concluded that cannabis improves catalepsy induced by haloperidol though the effect is not maintained on repeated cannabis administration. Cannabis alters the oxidative status of the brain in favor of reducing lipid peroxidation, but reduces brain glucose, which would impair brain energetics.

Pallidal hyperdopaminergic innervation underlying D2 receptor-dependent behavioral deficits in the schizophrenia animal model established by EGF

Epidermal growth factor (EGF) is one of the ErbB receptor ligands implicated in schizophrenia neuropathology as well as in dopaminergic development. Based on the immune inflammatory hypothesis for schizophrenia, neonatal rats are exposed to this cytokine and later develop neurobehavioral abnormality such as prepulse inhibition (PPI) deficit. Here we found that the EGF-treated rats exhibited persistent increases in tyrosine hydroxylase levels and dopamine content in the globus pallidus. Furthermore, pallidal dopamine release was elevated in EGF-treated rats, but normalized by subchronic treatment with risperidone concomitant with amelioration of their PPI deficits. To evaluate pathophysiologic roles of the dopamine abnormality, we administered reserpine bilaterally to the globus pallidus to reduce the local dopamine pool. Reserpine infusion ameliorated PPI deficits of EGF-treated rats without apparent aversive effects on locomotor activity in these rats. We also administered dopamine D1-like and D2-like receptor antagonists (SCH23390 and raclopride) and a D2-like receptor agonist (quinpirole) to the globus pallidus and measured PPI and bar-hang latencies. Raclopride (0.5 and 2.0 µg/site) significantly elevated PPI levels of EGF-treated rats, but SCH23390 (0.5 and 2.0 µg/site) had no effect. The higher dose of raclopride induced catalepsy-like changes in control animals but not in EGF-treated rats. Conversely, local quinpirole administration to EGF-untreated control rats induced PPI deficits and anti-cataleptic behaviors, confirming the pathophysiologic role of the pallidal hyperdopaminergic state. These findings suggest that the pallidal dopaminergic innervation is vulnerable to circulating EGF at perinatal and/or neonatal stages and has strong impact on the D2-like receptor-dependent behavioral deficits relevant to schizophrenia.

Pattern of acute induction of Homer1a gene is preserved after chronic treatment with first- and second-generation antipsychotics: effect of short-term drug discontinuation and comparison with Homer1a-interacting genes

Homer1a is a glutamate-related gene whose expression is induced by antipsychotics acutely (i.e. 90 min after treatment). Acute Homer1a expression is preserved after prolonged antipsychotic treatments, while the effects of short-term discontinuation after chronic antipsychotic treatment have not yet been assessed. Here, we studied early and long-term effects on gene expression by antipsychotics for Homer1a and other components of glutamatergic synapses. In the first paradigm, we evaluated Homer1a acute expression by single administration of antipsychotics (haloperidol 0.8 mg/kg, ziprasidone 10 and 4 mg/kg, clozapine 15 mg/kg). Haloperidol and ziprasidone induced Homer1a in the striatum. Induction by ziprasidone was dose-dependent. These results suggest that acute Homer1a expression correlates with dopaminergic affinity and motor side effects of antipsychotics. In the second paradigm, we studied antipsychotic-mediated long-term changes in Homer1a and glutamate-related genes. Rats were treated (21 days) with haloperidol 0.8 mg/kg, ziprasidone 4 mg/kg, or vehicle, and then sacrificed at 90 min (early time-point) or 24 h (delayed time-point) after last injection. Gene expression at these two time-points was compared. Homer1a preserved its pattern of expression at the early but not at the delayed time-point. Significant changes were also observed for PSD-95. The results suggest that Homer1a preserves its expression profile after chronic antipsychotics.

Emerging strategies for exploiting cannabinoid receptor agonists as medicines

Medicines that activate cannabinoid CB(1) and CB(2) receptor are already in the clinic. These are Cesamet (nabilone), Marinol (dronabinol; Delta(9)-tetrahydrocannabinol) and Sativex (Delta(9)-tetrahydrocannabinol with cannabidiol). The first two of these medicines can be prescribed to reduce chemotherapy-induced nausea and vomiting. Marinol can also be prescribed to stimulate appetite, while Sativex is prescribed for the symptomatic relief of neuropathic pain in adults with multiple sclerosis and as an adjunctive analgesic treatment for adult patients with advanced cancer. One challenge now is to identify additional therapeutic targets for cannabinoid receptor agonists, and a number of potential clinical applications for such agonists are mentioned in this review. A second challenge is to develop strategies that will improve the efficacy and/or the benefit-to-risk ratio of a cannabinoid receptor agonist. This review focuses on five strategies that have the potential to meet either or both of these objectives. These are strategies that involve: (i) targeting cannabinoid receptors located outside the blood-brain barrier; (ii) targeting cannabinoid receptors expressed by a particular tissue; (iii) targeting up-regulated cannabinoid receptors; (iv) targeting cannabinoid CB(2) receptors; or (v) 'multi-targeting'. Preclinical data that justify additional research directed at evaluating the clinical importance of each of these strategies are also discussed.

Reasons for cannabis use: patients with schizophrenia versus matched healthy controls

OBJECTIVE

The aim of the present study was to compare self-reported reasons for cannabis use in patients with schizophrenia with those of matched healthy controls.

METHODS

Thirty-six stable outpatients with schizophrenia treated with atypical antipsychotics and 36 matched controls were included. They completed a questionnaire exploring 15 common reasons for use, established in other studies. results: Overall, patients more frequently agreed with the proposed reasons for use than controls. More specifically, patients with schizophrenia more often stated that they consumed cannabis to fight boredom and to ease social contacts.

CONCLUSIONS

Stable schizophrenia outpatients treated with atypicals do not use cannabis in order to reduce side-effects of medication or symptoms of their disorder. Rather, they used cannabis to overcome a feeling of social exclusion. Therefore, enhancing social participation of cannabis-using patients might be an effective strategy for reducing consumption.

Cannabis using schizophrenia patients treated with atypical neuroleptics: do their symptoms differ from those of cannabis abstainers?

Several studies have found that symptom patterns of cannabis-using schizophrenia patients differ from those of nonusers. However, these investigations have mostly included patients treated with typical neuroleptics (TN). Since differing symptoms could also result from a TN-cannabis combination and might not be due to cannabis use per se, this study examined schizophrenia symptoms in a group of cannabis-using outpatients treated with atypical antipsychotics. Forty-two schizophrenia outpatients participated and were divided into three groups: cannabis abstainers, moderate users, and daily users. Patients with any substance use disorder other than cannabis abuse/dependence, or patients meeting criteria for schizotypal, schizoaffective, affective, anxiety, delusional, or personality disorders were excluded from the study. All patients completed a self-constructed questionnaire assessing demographic and drug use characteristics and were interviewed using the semistandardized Positive and Negative Syndrome Scale (PANSS). Cannabis use was assessed by self-declaration. No differences were found between the abstainers, the moderate, and the daily users on the PANSS scores. Thus, schizophrenia patients treated with atypical neuroleptics do not differ in symptom patterns whether using or not using cannabis. The study's limitations are noted.

Antipsychotic-induced alterations in CB1 receptor-mediated G-protein signaling and in vivo pharmacology in rats

Dysregulation of the endocannabinoid and dopamine systems has been implicated in schizophrenia. The purpose of this study was to examine the effects of sub-chronic treatment with two antipsychotics on CB1 receptor-mediated in vitro and in vivo effects. Adult and adolescent male and female rats were injected twice daily with haloperidol (0.3 mg/kg), clozapine (10 mg/kg), or saline for 10 days. Subsequently, CB1 receptor number and function were assessed by [3H]SR141716 and WIN55,212-2-stimulated [35S]GTPgammaS binding, respectively. The effects of sub-chronic antipsychotic treatment on the in vivo actions of Delta9-tetrahydrocannabinol (Delta9-THC) were also evaluated. In adult female rats, antipsychotic treatment attenuated maximal stimulation of CB1 receptor-mediated G-protein activity in the striatum (clozapine) and prefrontal cortex (both antipsychotics), but not in the ventral midbrain. Associated changes in CB1 receptor number were not observed, suggesting that this attenuation was not due to downregulation. In vivo, sub-chronic treatment with clozapine, but not haloperidol, attenuated Delta9-THC-induced suppression of activity in adult females, whereas neither drug altered hypothermia or catalepsy. In contrast, antipsychotic treatment did not change CB1 receptor-mediated G-protein activation in any brain region in adult male rats and in adolescents of either sex. In vivo, haloperidol, but not clozapine, enhanced Delta9-THC-mediated suppression of activity and hypothermia in adult male rats whereas neither antipsychotic affected Delta9-THC-induced in vivo effects in adolescent rats. These findings suggest that modulation of the endocannabinoid system might contribute in a sex- and age-selective manner to differences in motor side effects of clozapine versus haloperidol.

Effects of haloperidol on the behavioral, subjective, cognitive, motor, and neuroendocrine effects of Delta-9-tetrahydrocannabinol in humans

INTRODUCTION

Cannabinoids produce a spectrum of effects in humans including euphoria, cognitive impairments, psychotomimetic effects, and perceptual alterations. The extent to which dopaminergic systems contribute to the effects of Delta-9-tetrahydrocannabinol (Delta-9-THC) remains unclear. This study evaluated whether pretreatment with a dopamine receptor antagonist altered the effects of Delta-9-THC in humans.

MATERIALS AND METHODS

In a 2-test-day double-blind study, 28 subjects including healthy subjects (n = 17) and frequent users of cannabis (n = 11) were administered active (0.057 mg/kg) or placebo oral haloperidol in random order followed 90 and 215 min later by fixed order intravenous administration of placebo (vehicle) and active (0.0286 mg/kg) Delta-9-THC, respectively.

RESULTS

Consistent with previous reports, intravenous Delta-9-THC produced psychotomimetic effects, perceptual alterations, and subjective effects including "high." Delta-9-THC also impaired verbal recall and attention. Haloperidol pretreatment did not reduce any of the behavioral effects of Delta-9-THC. Haloperidol worsened the immediate free and delayed free and cued recall deficits produced by Delta-9-THC. Haloperidol and Delta-9-THC worsened distractibility and vigilance. Neither drug impaired performance on a motor screening task, the Stockings of Cambridge task, or the delayed match to sample task. Frequent users had lower baseline plasma prolactin levels and blunted Delta-9-THC induced memory impairments.

CONCLUSIONS

The deleterious effects of haloperidol pretreatment on the cognitive effects of Delta-9-THC are consistent with the preclinical literature in suggesting crosstalk between DAergic and CBergic systems. However, it is unlikely that DA D(2) receptor mechanisms play a major role in mediating the psychotomimetic and perceptual altering effects of Delta-9-THC. Further investigation is warranted to understand the basis of the psychotomimetic effects of Delta-9-THC and to better understand the crosstalk between DAergic and CBergic systems.

The CNR1 gene as a pharmacogenetic factor for antipsychotics rather than a susceptibility gene for schizophrenia

Neurobiological research suggests a significant role of the endocannabinoid system in schizophrenia vulnerability and also in the quality of response to antipsychotics. Genetics offer an opportunity to disentangle its involvement in the disease vulnerability vs an influence on antipsychotics' effects. The possible role of a tag SNP (the 1359G/A polymorphism) of the gene encoding the cannabinoid receptor type 1 (CNR1) in schizophrenia and/or therapeutic response to atypical antipsychotics was assessed in a cohort of 133 French schizophrenic patients compared to 141 normal control subjects. No difference in 1359G/A polymorphism was observed between patients and control subjects, and no relationships were noted between this polymorphism and any clinical parameter considered as potential intermediate factor. However, the G allele frequency was significantly higher among non-responsive vs responsive patients, with a dose effect of the G allele. In contrast, no association was found for three other genetic polymorphisms of the CNR1 gene. The G allele of the CNR1 gene polymorphisms could be a psychopharmacogenetic rather than a vulnerability factor regarding schizophrenia and its treatment.

Delta 9-tetrahydrocannabinol-induced catalepsy-like immobilization is mediated by decreased 5-HT neurotransmission in the nucleus accumbens due to the action of glutamate-containing neurons

Delta(9)-tetrahydrocannabinol (THC) has been reported to induce catalepsy-like immobilization, but the mechanism underlying this effect remains unclear. In the present study, in order to fully understand the neural circuits involved, we determined the brain sites involved in the immobilization effect in rats. THC dose-dependently induced catalepsy-like immobilization. THC-induced catalepsy-like immobilization is mechanistically different from that induced by haloperidol (HPD), because unlike HPD-induced catalepsy, animals with THC-induced catalepsy became normal again following sound and air-puff stimuli. THC-induced catalepsy was reversed by SR141716, a selective cannabinoid CB(1) receptor antagonist. Moreover, THC-induced catalepsy was abolished by lesions in the nucleus accumbens (NAc) and central amygdala (ACE) regions. On the other hand, HPD-induced catalepsy was suppressed by lesions in the caudate putamen (CP), substantia nigra (SN), globus pallidus (GP), ACE and lateral hypothalamus (LH) regions. Bilateral microinjection of THC into the NAc region induced catalepsy-like immobilization. This THC-induced catalepsy was inhibited by serotonergic drugs such as 5-hydroxy-L-tryptophan (5-HTP), a 5-HT precursor, and 5-methoxy-N,N-dimethyltryptamine (5-MeODMT), a 5-HT receptor agonist, as well as by anti-glutamatergic drugs such as MK-801 and amantadine, an N-methyl-d-aspartate (NMDA) receptor antagonist. THC significantly decreased 5-HT and glutamate release in the NAc, as shown by in vivo microdialysis. SR141716 reversed and MK-801 inhibited this decrease in 5-HT and glutamate release. These findings suggest that the THC-induced catalepsy is mechanistically different from HPD-induced catalepsy and that the catalepsy-like immobilization induced by THC is mediated by decreased 5-HT neurotransmission in the nucleus accumbens due to the action of glutamate-containing neurons.

Involvement of 5-hydroxytryptamine1A receptors in Delta9-tetrahydrocannabinol-induced catalepsy-like immobilization in mice

The present study investigated the involvement of 5-hydroxytryptamine(1A) (5-HT(1A)) receptors in Delta(9)-tetrahydrocannabinol (THC)-induced catalepsy-like immobilization in mice. THC (10 mg/kg, i.p.) induced catalepsy-like immobilization but had no effect on motor coordination in the rota-rod test. The selective cannabinoid CB(1) receptor antagonist rimonabant (3 mg/kg, i.p.) completely antagonized THC-induced catalepsy-like immobilization. The 5-HT(1A)/5-HT(7) receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 0.3 and 1 mg/kg, i.p.) and 5-HT(1A) receptor partial agonist buspirone (0.06 and 0.1 mg/kg, i.p.) inhibited this THC-induced catalepsy-like immobilization. Moreover, the selective 5-HT(1A) receptor antagonist N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridinyl) cyclohezane carboxamide dihydrochloride (WAY100635; 0.3 or 1 mg/kg, i.p.) reversed the inhibition of THC-induced catalepsy-like immobilization by 8-OH-DPAT (1 mg/kg) or buspirone (0.06 mg/kg). In contrast, the selective 5-HT(7) receptor antagonist (R)-3-[2-[2-(4-methylpiperidin-1-yl)ethyl]pyrrolidine-1-sulfonyl]phenol hydrochloride (SB269970) had no effect on this inhibitory effect of 8-OH-DPAT. On the other hand, WAY100635 (0.3 and 1 mg/kg, i.p.) enhanced the catalepsy-like immobilization induced by THC (6 mg/kg, i.p.). These findings suggest that the 5-HT(1A) receptors are involved in THC-induced catalepsy-like immobilization.

Antipsychotics improve Delta9-tetrahydrocannabinol-induced impairment of the prepulse inhibition of the startle reflex in mice

Recently, cannabinoid receptor agonists have been reported to impair prepulse inhibition (PPI) of the startle reflex. In the current study, we examined the effect of Delta9-tetrahydrocannabinol (THC), the principal psychoactive component of cannabis, on the PPI, and found that THC (10 mg/kg, i.p.) impaired the PPI concomitant with a decrease in the startle response. Antipsychotics such as haloperidol (0.3 mg/kg, i.p.) and risperidone (0.1 mg/kg, i.p.), which are potent dopamine D2 receptor antagonists, and SR141716 (10 mg/kg, i.p.), a CB1 cannabinoid receptor antagonist, reversed these THC-induced PPI deficits. Moreover, THC (10 mg/kg) increased dopamine (DA) release in the nucleus accumbens but not medial prefrontal cortex over a 50-100-min period (time of PPI test) after treatment, and SR141716 (10 mg/kg) reversed this increase in DA release induced by THC. These results suggest that dopaminergic hyperfunction in the nucleus accumbens may be involved in THC-induced PPI deficits.

Molecular mapping of striatal subdivisions in juvenile Macaca Mulata

The striatum of the primate brain can be subdivided into three distinct anatomical subregions: caudate (CAU), putamen (PUT), and ventral striatum (VS). Although these subregions share several anatomical connections, cell morphological, and histochemical features, they differ considerably in their vulnerability to different neurological and psychiatric diseases, and these brain regions have significantly different functions in health and disease. In order to better understand the molecular underpinnings of the different disease and functional vulnerabilities, transcriptional profiles were generated from the CAU, PUT, and VS of five juvenile rhesus macaques (Macaca mulatta) using human cDNA neuromicroarrays containing triplicate spots of 1227 cDNAs. Differences in microarray gene expression were assessed using z score analysis and 1.5-fold change between paired subregions. Clustering of genes based on dissimilarity of expression patterns between regions revealed subregion specific expression profiles encoding G-protein-coupled receptor signaling transcripts, transcription factors, kinases and phosphatases, and cell signaling and signal transduction transcripts. Twelve transcripts were examined using quantitative real-time PCR (qPCR), and 81% demonstrated alterations similar to those seen with microarray analysis, some of which were statistically significant. Subregion specific transcription profiles support the anatomical differentiation and potential disease vulnerabilities of the respective subregions.

Harm reduction--the cannabis paradox

This article examines harm reduction from a novel perspective. Its central thesis is that harm reduction is not only a social concept, but also a biological one. More specifically, evolution does not make moral distinctions in the selection process, but utilizes a cannabis-based approach to harm reduction in order to promote survival of the fittest. Evidence will be provided from peer-reviewed scientific literature that supports the hypothesis that humans, and all animals, make and use internally produced cannabis-like products (endocannabinoids) as part of the evolutionary harm reduction program. More specifically, endocannabinoids homeostatically regulate all body systems (cardiovascular, digestive, endocrine, excretory, immune, nervous, musculo-skeletal, reproductive). Therefore, the health of each individual is dependant on this system working appropriately.

Streptozotocin-induced diabetes differentially modifies haloperidol- and γ-hydroxybutyric acid (GHB)-induced catalepsy

To examine whether dopamine-mediated behavioral effects are altered in diabetes, this study compared the cataleptic effects of the dopamine receptor antagonist haloperidol (0.032-0.56 mg/kg) and gamma-hydroxybutyric acid (GHB; 56-1000 mg/kg) in control and streptozotocin (STZ)-treated rats. Haloperidol and GHB produced catalepsy in control and diabetic rats; haloperidol was less potent in diabetic rats (D(50)=0.44 mg/kg) than in controls (D(50)=0.19 mg/kg), while GHB was more potent in diabetic rats (D(50)=392 mg/kg) than in controls (D(50)=550 mg/kg). In diabetic rats, the non-competitive N-methyl-d-aspartate (NMDA) receptor antagonist dizocilpine (0.32 mg/kg) further attenuated haloperidol-induced catalepsy (D(50)=1.2 mg/kg) and further enhanced GHB-induced catalepsy (D(50)=248 mg/kg). That haloperidol is less potent to produce catalepsy in diabetic rats is consistent with reports of altered dopamine receptor binding in diabetes.