A characteristic pattern of behavioral and physiological effects is produced by marijuana and its principal psychoactive component, THC, in humans. However, THC’s sites of action in the human brain and their relationships to the drug’s actions are not well described. We have now studied in frequent marijuana users, the effects of two doses of THC (1 and 3 mg iv over 1 min) that produce effects similar to those seen with marijuana use in a social situation, on regional brain activity using BOLD fMRI. The subjects reported that the intensity of the “high” produced by the 3 mg dose was twice that of the lower dose (8/10 vs. 4.5/10). A modest dose-related tachycardia was also observed.Both increases and decreases in brain activity as measured by BOLD fMRI were seen in discrete brain regions. The 3 mg dose of THC produced time-related decreases in fMRI signal in the cerebellum including the region of the dentate nucleus, the middle temporal gyrus and the orbitofrontal region. Decreases were also seen in several...

As the market for cannabis concentrate products continues to grow, the lack of research regarding the combined and differential effects of concentrated forms of the two most prominent cannabinoids, THC and CBD, becomes more glaring. The present study an...

The aim of this study was to evaluate the effects of cannabidiol (CBD) in alcohol reinforcement, motivation and relapse in C57BL/6J mice. To this purpose, the effects of CBD (60 mg/kg i.p.) and ethanol on rectal temperature (3 g/kg p.o.), ethanol-handli...

Cannabidiol, one of the main compounds present in the plant Cannabis sativa, has recently emerged as a potential drug for the treatment of different psychiatric disorders, based on its anxiolytic, antidepressant and antipsychotic properties. However, so...

Altered time perception is one of the most frequently-reported subjective experiences associated with the “high” induced by marijuana (MJ). Intoxicated subjects typically experience time as passing more quickly relative to real time i.e., MJ increases the subjective time rate. We assessed the acute and chronic effects of smoking MJ or placebo cigarettes (provided by NIDA) on a self-paced finger tapping task using a double-blind, placebo-control design. Volunteers (n = 10) who smoked marijuana recreationally an average of 3 times a month (low-use group) were compared with chronic users (n = 15) who smoked marijuana daily for an average duration of 5 years. A tone was presented for 50s with a beat to beat interval of 730ms, and was then turned off. Subjects were instructed to tap in time with the tone and to continue tapping at the same pace for 50s after it terminated. Tone-paced tapping did not change in either group after smoking placebo or MJ, indicating that MJ did not cause sensory-motor impairment on ...

Excitotoxicity is a paradigm used to explain the biochemical events in both acute neuronal damage and in slowly progressive, neurodegenerative diseases. Here, we show in a longitudinal magnetic resonance imaging study that Δ9-tetrahydrocannabinol (Δ9-THC), the main active compound in marijuana, reduces neuronal injury in neonatal rats injected intracerebrally with the Na+/K+-ATPase inhibitor ouabain to elicit excitotoxicity. In the acute phase Δ9-THC reduced the volume of cytotoxic edema by 22%. After 7 d, 36% less neuronal damage was observed in treated rats compared with control animals. Coadministration of the CB1 cannabinoid receptor antagonist SR141716 prevented the neuroprotective actions of Δ9-THC, indicating that Δ9-THC afforded protection to neurons via the CB1 receptor. In Δ9-THC-treated rats the volume of astrogliotic tissue was 36% smaller. The CB1 receptor antagonist did not block this effect. These results provide evidence that the cannabinoid system can serve to protect the brain against neu...

Epidemiological and clinical studies suggest that a neurodevelopmental dysfunction could be one of the main exploratory hypotheses of schizophrenia (SCZ), which symptoms lead to severe personal and social dysfunctions. A variety of animal and human stud...

Recent clinical trials suggest that cannabidiol (CBD), a non-psychoactive component of cannabis, can reduce seizure frequency in several forms of pediatric epilepsy. While the exact anti-seizure mechanism of CBD is unclear, one leading hypothesis predic...

Migraine affects 15% of the world’s population, yet treatment options are either ineffective or accompanied by adverse effects such as medication overuse headache. Anecdotal and clinical evidence suggest that cannabinoids present in marijuana have anti-...

Marijuana is the most widely used illicit drug world-wide because of its psychoactive compound, ∆9-tetrahydrocannabinol (THC). The plant, Cannabis sativa, however contains a myriad of other non-psychoactive cannabinoids. In Jamaica, it is smoked, drank ...