Marihuana: Effects on Neuronal Excitability and Seizure Threshold
- Elisabeth Gordon
- Orrin Devinsky
In the late 19th century, British neurologists found that cannabis had a limited role in epilepsy therapy. Cannabinoid receptors are found in the brainstem, limbic and neocortical areas that modulate seizure activity. The recent studies of the effects of THC, CBD, and related cannabinoids in animal models of epilepsy reveal that (1) the effects vary significantly in different models, in different species, and for the different derivatives; (2) the mechanisms by which the cannabinoids exert their anti-or proconvulsant effects is not well-defined; and (3) the effects of acute administration (e.g., increasing seizure threshold) may be followed, in certain models, by a rebound effect (e.g., decreasing seizure threshold).
No well-controlled studies have evaluated cannabinoids in the treatment of epilepsy patients. However, clinical anecdotes and single case reports suggest that marijuana may reduce seizure frequency or, conversely may provoke seizure activity in select cases, while in most instances it has no significant effect on seizure activity. Several clinical studies have examined the efficacy of CBD on seizure frequency. These studies found either some reduction in seizure frequency or no statistically significant reduction compared to placebo. The few epidemiological studies that have been conducted suggest that marijuana use may protect against seizures induced by illicit drugs such as heroin and cocaine. The limited evidence therefore suggest that marijuana and the cannabinoids may have antiepileptic effects in man, but these effects may be specific to partial or tonic-clonic seizures.
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In the late 19th century, British neurologists found that cannabis had a limited role in epilepsy therapy. Cannabinoid receptors are found in the brainstem, limbic and neocortical areas that modulate…
AsianScientist (Sep. 26, 2017) – The dangers of cannabinoid abuse have been exposed by researchers in Japan who identified compounds in natural and synthetic marijuana that cause life-threatening seizures. The researchers report their findings in the journal Scientific Reports.
Marijuana is the most commonly abused drug in the world, and the advent of synthetic cannabinoids creates additional challenges to society because of their higher potency and ability to escape drug detection screenings. There is currently minimal information on the pharmacology and potential harm of synthetic cannabinoids. As several governments proceed with legalization of cannabinoids for both medical and recreational use, studies on the adverse side-effects of canniboids are warranted.
In this study, a team of researchers led by Professors Olga Malyshevskaya and Yoshihiro Urade of the International Institute for Integrative Sleep Medicine at the University of Tsukuba discovered that seizures, a life-threatening condition, can be induced by natural Δ9-tetrahydrocannabinol (Δ9-THC, main constituent of marijuana) or the synthetic cannabinoid JWH-018 (main component of synthetic blend “Spice”) in mice.
This was demonstrated by video monitoring and movement activity tracking of mice, alongside continuous recording of the animals’ electrical brain activity when exposed to the compounds. Based on their data, the researchers proposed a potential preventive measure against cannabinoid overdose. The pretreatment of mice with a cannabinoid-1-receptor specific antagonist, AM-251, prevented cannabinoid-induced seizures.
“Our study is quite important because people see marijuana as a soft drug and are unaware of the particularly severe effects caused by those cannabinoids,” said Malyshevskaya.
Considering the recent irreversible spread of synthetic cannabinoids and their impact on human health, this data should serve as a public health alert, informing the decision-making of healthcare professionals and policy makers. Clinicians in the emergency departments of hospitals should therefore suspect seizure activity in patients who have a history of cannabinoid intoxication.
The article can be found at: Malyshevskaya et al. (2017) Natural (∆ 9 -THC) and Synthetic (JWH-018) Cannabinoids Induce Seizures by Acting Through the Cannabinoid CB1 Receptor.
Source: University of Tsukuba; Photo: Pixabay.
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