The dual neuroprotective–neurotoxic profile of cannabinoid drugs

Extensive in vitro and in vivo studies have shown that cannabinoid drugs have neuroprotective properties and suggested that the endocannabinoid system may be involved in endogenous neuroprotective mechanisms. On the other hand, neurotoxic effects of cannabinoids in vitro and in vivo were also descri...

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Bibliographic Details
Published in:British journal of pharmacology 2011-08, Vol.163 (7), p.1391-1401
Main Authors: Sarne, Yosef, Asaf, Fadi, Fishbein, Miriam, Gafni, Mikhal, Keren, Ora
Format: Article
Language:English
Subjects:
Animals
Brain - drug effects
Brain damage
Cannabinoids - adverse effects
Cannabinoids - pharmacology
carbon monoxide intoxication
Dose-Response Relationship, Drug
Drug dosages
Humans
neuroprotection
Neuroprotective Agents - adverse effects
Neuroprotective Agents - pharmacology
Neurotoxicity
Neurotoxicity Syndromes - etiology
postconditioning
preconditioning
PTZ (pentylenetetrazole)
Reviews
Rodents
seizures
THC (Δ9‐tetrahydrocannabinol)
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Summary:Extensive in vitro and in vivo studies have shown that cannabinoid drugs have neuroprotective properties and suggested that the endocannabinoid system may be involved in endogenous neuroprotective mechanisms. On the other hand, neurotoxic effects of cannabinoids in vitro and in vivo were also described. Several possible explanations for these dual, opposite effects of cannabinoids on cellular fate were suggested, and it is conceivable that various factors may determine the final outcome of the cannabinoid effect in vivo. In the current review, we focus on one of the possible reasons for the dual neuroprotective/neurotoxic effects of cannabinoids in vivo, namely, the opposite effects of low versus high doses of cannabinoids. While many studies reported neuroprotective effects of the conventional doses of cannabinoids in various experimental models for acute brain injuries, we have shown that a single administration of an extremely low dose of Δ9‐tetrahydrocannabinol (THC) (3–4 orders of magnitude lower than the conventional doses) to mice induced long‐lasting mild cognitive deficits that affected various aspects of memory and learning. These findings led to the idea that this low dose of THC, which induces minor damage to the brain, may activate preconditioning and/or postconditioning mechanisms and thus will protect the brain from more severe insults. Indeed, our recent findings support this assumption and show that a pre‐ or a postconditioning treatment with extremely low doses of THC, several days before or after brain injury, provides effective long‐term cognitive neuroprotection. The future therapeutical potential of these findings is discussed. LINKED ARTICLES This article is part of a themed issue on Cannabinoids in Biology and Medicine. To view the other articles in this issue visit http://dx.doi.org/10.1111/bph.2011.163.issue‐7
ISSN:0007-1188
1476-5381
1476-5381
DOI:10.1111/j.1476-5381.2011.01280.x