Despite increased prevalence of maternal cannabis use, little is understood regarding potential long-term effects of prenatal cannabis exposure (PCE) on neurodevelopmental outcomes. While neurodevelopmental cannabis exposure increases the risk of developing affective/mood disorders in adulthood, the precise neuropathophysiological mechanisms in male and female offspring are largely unknown. Given the interconnectivity of the endocannabinoid (ECb) system and the brain’s fatty acid pathways, we hypothesized that prenatal exposure to Δ9-tetrahydrocannabinol (THC) may dysregulate fetal neurodevelopment through alterations of fatty-acid dependent synaptic and neuronal function in the mesolimbic system. To investigate this, pregnant Wistar rats were exposed to vehicle or THC (3 mg/kg) from gestational day (GD)7 until GD22. Anxiety-like, depressive-like, and reward-seeking behavior, electrophysiology, and molecular assays were performed on adult male/female offspring. Imaging of fatty acids using matrix-assisted ...

Cannabis and ecstasy (MDMA) are two of the most widely used recreational drugs often taken in combination by drug users. The aim of the present study was to investigate whether subthreshold doses of MDMA and delta9-tetrahydrocannabinol (THC) produced synergistic rewarding effects in mice. A conditioned place preference paradigm (CPP) was used to assess the rewarding properties of MDMA (0, 3, and 10 mg/kg, i.p.) alone and in combination with THC (0 and 0.3 mg/kg, i.p.). In addition, in vivo microdialysis in freely moving mice was performed in order to evaluate changes in extracellular dopamine levels in the nucleus accumbens following single or combined administration of MDMA (0 and 3 mg/kg) and THC (0 and 0.3 mg/kg). MDMA at the dose of 10 mg/kg produced a significant CPP, while neither MDMA (3 mg/kg) nor THC (0.3 m/kg) produced this effect. The combination of ineffective doses of MDMA and THC induced a significant CPP compared to each drug given by itself. However, THC did not potentiate the CPP produced ...

Marijuana consumption elicits diverse physiological and psychological effects in humans, including memory loss. Here we report that Δ9-tetrahydrocannabinol (THC), the major psychoactive component of marijuana, is toxic for hippocampal neurons. Treatment of cultured neurons or hippocampal slices with THC caused shrinkage of neuronal cell bodies and nuclei as well as genomic DNA strand breaks, hallmarks of neuronal apoptosis. Neuron death induced by THC was inhibited by nonsteroidal anti-inflammatory drugs, including indomethacin and aspirin, as well as vitamin E and other antioxidants. Furthermore, treatment of neurons with THC stimulated a significant increase in the release of arachidonic acid. We hypothesize that THC neurotoxicity is attributable to activation of the prostanoid synthesis pathway and generation of free radicals by cyclooxygenase. These data suggest that some of the memory deficits caused by cannabinoids may be caused by THC neurotoxicity.

Current findings demonstrate that cannabinoids (CBs) can elicit both neuroprotection and neuromodulation, although detailed mechanisms remain to be elucidated. Here we investigated whether the non-psychotropic plant cannabinoid, cannabidiol (CBD), can modulate Ca2+ signalling in hippocampal cells. Hippocampi of Sprague-Dawley neonates (1-3 days) were dissected and the tissue enzymatically dissociated. Cultures were matured for 5-12 days and loaded with the fluorescent Ca2+ indicator Fura-2AM (6–10 µM). Dishes were perfused with HEPES buffered solution (containing 0.5 µM TTX) and images captured at 350 and 380 nm to calculate [Ca2+]i measurements as ratio units. CBD application (1 µM) induced a Ca2+ response in both neurones and glia (46% and 83%, respectively). Interestingly, the CBD-induced Ca2+ response was significantly enhanced by the CB1 antagonist AM281 (1 µM, 400%) and in cultures pre-incubated with the Gi/o protein blocker, pertussis toxin (PTX, 100 ng/ml, 300%), indicative of a CB1 receptor depend...

The non-psychoactive phytocannabinoid cannabidiol (CBD) has been shown to have analgesic effects in animal studies but little is known about its mechanism of action. We examined effects of CBD on intrinsic excitability of primary pain-sensing neurons. Studying acutely-dissociated capsaicin-sensitive mouse DRG neurons at 37°C, we found that CBD effectively inhibited repetitive action potential firing, from 15-20 action potentials evoked by 1-s current injections in control to 1-3 action potentials with 2 μM CBD. Reduction of repetitive firing was accompanied by reduction of action potential height, widening of action potentials, reduction of the afterhyperpolarization, and increased propensity to enter depolarization block. Voltage clamp experiments showed that CBD inhibited both TTX-sensitive (TTX-S) and TTX-resistant (TTX-R) sodium currents in a use-dependent manner. CBD showed strong state-dependent inhibition of TTX-R channels, with fast binding to inactivated channels during depolarizations and slow un...

Chronic cannabinoid exposure results in tolerance to cannabinoid-induced locomotor effects which are mediated by the cannabinoid receptors (CB1R) located in motor control region, such as cerebellum. In cerebellar cortex, acute activation of presynaptic CB1R suppresses parallel fibers (PF) synaptic inputs to Purkinje cells (PC). Whole-cell patch-clamp recordings have been carried out in PC to analyze the properties of evoked excitatory synaptic transmission in mice chronically exposed to Δ9-THC or to its vehicle. Paired-pulse facilitation (PPF) was used to analyze PF-PC short-term synaptic plasticity. We observed a decreased PPF in mice chronically treated with THC, indicating an increased release probability after prolonged cannabinoid exposure. In addition, inhibition of PF-PC synaptic transmission induced by the selective CB1R agonist CP55940 is decreased in THC-treated mice. This suggests that, following chronic THC treatment, functional tolerance to the CB1R agonist occurs at cerebellar PF-PC synapses,...

Objective: Cannabidiol (CBD) a non-psychoactive component of marijuana, prevents glutamate-mediated neurotoxicity and reactive oxygen species induced cell death in neuronal culture. This study was designed to evaluate the neuroprotective efficacy of CBD in a model of global cerebral ischemia in dogs. Methods: 18 adult female Beagles underwent 10 min Cardiac Arrest. then restoration of spontaneous circulation followed by 24 hours of intensive care. Immediately following resuscitation, half of the animals received CBD (5 mg/kg IV) while the others received drug vehicle only. 23 hr after resuscitation, dogs were awakened and examined for neurologic deficit by blinded examiners using a standardized neurologic deficit scoring (NDS) system, measuring level of consciousness, respiration, cranial nerves, motor/sensory function and behavior. (0 = nl, 100 = brain death). NDS has previously been shown to correlate with neuronal histopathology. Results: No differences were noted between experimental groups in terms of...

Δ9-Tetrahydrocannabinol (Δ9-THC), the major psychoactive compound of marijuana, exerts direct cellular effects through the activation of G-protein-coupled CB1 and CB2 receptors located mainly in the brain and the immune system, respectively. The molecular mechanism by which cannabinoids alter gene expression in the brain is not well understood. The CB1 receptors coupled to Gi proteins activate both potassium channels and members of the mitogen-associated protein kinase family, and also inhibit adenylate cyclase and voltage-gated calcium channels. Moreover, there is evidence for an alternative CB1-mediated signalling pathway involving the activation of adenylate cyclase through stimulatory Gs proteins. The modulation of the phosphorylated cAMP-response element binding protein (p-CREB) by Δ9-THC was investigated in cerebellar granule cells, known to display an high distribution of CB1 receptors, to elucidate the cellular mechanism involved in CB1 receptors activation. Different concentrations (0, 0.3, 3, 30,...

Despite increased prevalence of maternal cannabis use, little is understood regarding potential long-term effects of prenatal cannabis exposure (PCE) on neurodevelopmental outcomes. While neurodevelopmental cannabis exposure increases the risk of developing affective/mood disorders in adulthood, the precise neuropathophysiological mechanisms in male and female offspring are largely unknown. Given the interconnectivity of the endocannabinoid system and the brain's fatty acid pathways, we hypothesized that prenatal exposure to Δ9-tetrahydrocannabinol (THC) may dysregulate fetal neurodevelopment through alterations of fatty-acid dependent synaptic and neuronal function in the mesolimbic system. To investigate this, pregnant Wistar rats were exposed to vehicle or THC (3mg/kg) from gestational day (GD) 7 until GD22. Anxiety-like, depressive-like, and reward-seeking behaviour, electrophysiology, and molecular assays were performed on adult male/female offspring. Imaging of fatty acids using matrix-assisted laser...

The chronic administration of Δ9-tetrahydrocannabinol (Δ9-THC) produces tolerance to its behavioral effects, and such tolerance can be associated with changes in cannabinoid receptor number as well as function. The purpose of the present study was to identify patterns of functional activity that accompany chronic Δ9-THC administration utilizing quantitative 2-[14C]deoxyglucose autoradiography (2DG). Male Sprague-Dawley rats were treated with Δ 9-THC (10 mg/kg, i.p.) or vehicle for either one or 21 days. Metabolic mapping with the 2DG method was applied 15 minutes after the final drug treatment. The single administration of Δ9-THC produced a global effect, significantly depressing rates of glucose utilization in 35 of 39 brain structures measured. In contrast, the administration of Δ9-THC, following repeated exposure, did not significantly alter rates of glucose utilization in the majority of structures analyzed. These data demonstrate that tolerance develops to the cerebral metabolic effects of Δ9-THC foll...