A role for endocannabinoids in viral-induced dyskinetic and convulsive phenomena.
Dyskinesias and seizures are both medically refractory disorders for which cannabinoid-based treatments have shown early promise as primary or adjunctive therapy. Using the Borna disease (BD) virus rat, an animal model of viral encephalopathy with spontaneous hyperkinetic movements and seizure susceptibility, we identified a key role for endocannabinoids in the maintenance of a balanced tone of activity in extrapyramidal and limbic circuits. BD rats showed significant elevations of the endocannabinoid anandamide in subthalamic nucleus, a relay nucleus compromised in hyperkinetic disorders. While direct and indirect cannabinoid agonists had limited motor effects in BD rats, abrupt reductions of endocannabinoid tone by the CB1 antagonist SR141716A (0.3 mg/kg, i.p.) caused seizures characterized by myoclonic jerks time-locked to periodic spike/sharp wave discharges on hippocampal electroencephalography. The general opiate antagonist naloxone (NLX) (1 mg/kg, s.c.), another pharmacologic treatment with potential efficacy in dyskinesias or L-DOPA motor complications, produced similar seizures. No changes in anandamide levels in hippocampus and amygdala were found in convulsing NLX-treated BD rats. In contrast, NLX significantly increased anandamide levels in the same areas of normal uninfected animals, possibly protecting against seizures. Pretreatment with the anandamide transport blocker AM404 (20 mg/kg, i.p.) prevented NLX-induced seizures. These findings are consistent with an anticonvulsant role for endocannabinoids, counteracting aberrant firing produced by convulsive agents, and with a functional or reciprocal relation between opioid and cannabinoid tone with respect to limbic convulsive phenomena.
Solbrig
Marylou V
MV
Department of Neurology, 3226 Gillespie Neuroscience Research Bldg., University of California-Irvine, Irvine, CA 92697-4292, USA. msolbrig@uci.edu
Adrian
Russell
R
Baratta
Janie
J
Piomelli
Daniele
D
Giuffrida
Andrea
A
D000818:Animals; D000927:Anticonvulsants / Q000494:pharmacology / Q000627:therapeutic use; D001095:Arachidonic Acids / Q000378:metabolism / Q000494:pharmacology; D001479:Basal Ganglia / Q000187:drug effects / Q000503:physiopathology / Q000821:virology; D001890:Borna Disease / Q000188:drug therapy* / Q000503:physiopathology / Q000821:virology; D063385:Cannabinoid Receptor Modulators / Q000494:pharmacology* / Q000627:therapeutic use; D003292:Convulsants / Q000037:antagonists & inhibitors; D004195:Disease Models, Animal; D063388:Endocannabinoids; D008032:Limbic System / Q000187:drug effects / Q000503:physiopathology / Q000821:virology; D008297:Male; D009069:Movement Disorders / Q000188:drug therapy* / Q000503:physiopathology / Q000821:virology; D009270:Naloxone / Q000037:antagonists & inhibitors; D009292:Narcotic Antagonists / Q000494:pharmacology; D010880:Piperidines / Q000037:antagonists & inhibitors; D053284:Polyunsaturated Alkamides; D011720:Pyrazoles / Q000037:antagonists & inhibitors; D051381:Rats; D011917:Rats, Inbred Lew; D043884:Receptor, Cannabinoid, CB1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D000077285:Rimonabant; D012640:Seizures / Q000188:drug therapy* / Q000503:physiopathology / Q000821:virology
D000927:Anticonvulsants; D001095:Arachidonic Acids; D063385:Cannabinoid Receptor Modulators; D003292:Convulsants; D063388:Endocannabinoids; D009292:Narcotic Antagonists; D010880:Piperidines; D053284:Polyunsaturated Alkamides; D011720:Pyrazoles; D043884:Receptor, Cannabinoid, CB1; D009270:Naloxone; D000077285:Rimonabant; C078814:anandamide; C107594:N-(4-hydroxyphenyl)arachidonylamide