Cannabinoids produce neuroprotection by reducing intracellular calcium release from ryanodine-sensitive stores.
Exogenously administered cannabinoids are neuroprotective in several different cellular and animal models. In the current study, two cannabinoid CB1 receptor ligands (WIN 55,212-2, CP 55,940) markedly reduced hippocampal cell death, in a time-dependent manner, in cultured neurons subjected to high levels of NMDA (15 microM). WIN 55,212-2 was also shown to inhibit the NMDA-induced increase in intracellular calcium concentration ([Ca2+](i)) indicated by FURA-2 fluorescence imaging in the same cultured neurons. Changes in [Ca2+](i) occurred with similar concentrations (25-100 nM) and in the same time-dependent manner (pre-exposure 1-15 min) as CB1 receptor mediated neuroprotective actions. Both effects were blocked by the CB1 receptor antagonist SR141716A. An underlying mechanism was indicated by the fact that (1) the NMDA-induced increase in [Ca2+](i) was inhibited by ryanodine, implicating a ryanodine receptor (RyR) coupled intracellular calcium channel, and (2) the cannabinoid influence involved a reduction in cAMP cAMP-dependent protein kinase (PKA) dependent phosphorylation of the same RyR levels that regulate channel. Moreover the time course of CB1 receptor mediated inhibition of PKA phosphorylation was directly related to effective pre-exposure intervals for cannabinoid neuroprotection. Control studies ruled out the involvement of inositol-trisphosphate (IP3) pathways, enhanced calcium reuptake and voltage sensitive calcium channels in the neuroprotective process. The results suggest that cannabinoids prevent cell death by initiating a time and dose dependent inhibition of adenylyl cyclase, that outlasts direct action at the CB1 receptor and is capable of reducing [Ca2+](i) via a cAMP/PKA-dependent process during the neurotoxic event.
Zhuang
Shou-Yuan
SY
Department of Physiology and Pharmacology, Wake Forest University Health Sciences, Winston-Salem, NC 27157, USA.
Bridges
Daniel
D
Grigorenko
Elena
E
McCloud
Stephen
S
Boon
Andrew
A
Hampson
Robert E
RE
Deadwyler
Sam A
SA
D000818:Animals; D048588:Benzoxazines / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D018929:Cell Culture Techniques; D016923:Cell Death / Q000187:drug effects; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D003511:Cyclohexanols / Q000494:pharmacology; D003620:Dantrolene / Q000494:pharmacology; D004347:Drug Interactions; D004963:Estrenes / Q000494:pharmacology; D005333:Fetus; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism; D047028:Macrocyclic Compounds / Q000494:pharmacology; D009025:Morpholines / Q000494:pharmacology; D016202:N-Methylaspartate / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D019319:Okadaic Acid / Q000494:pharmacology; D010080:Oxazoles / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D011720:Pyrazoles / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D043884:Receptor, Cannabinoid, CB1 / Q000819:agonists* / Q000037:antagonists & inhibitors*; D000077285:Rimonabant; D012433:Ryanodine / Q000494:pharmacology*; D013873:Thionucleotides / Q000494:pharmacology
D048588:Benzoxazines; D003511:Cyclohexanols; D004963:Estrenes; D047028:Macrocyclic Compounds; D009025:Morpholines; D009281:Naphthalenes; D018696:Neuroprotective Agents; D010080:Oxazoles; D010880:Piperidines; D011720:Pyrazoles; D011760:Pyrrolidinones; D043884:Receptor, Cannabinoid, CB1; D013873:Thionucleotides; C108644:xestospongin A; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; C074854:U 73343; D012433:Ryanodine; D019319:Okadaic Acid; C016957:adenosine-3',5'-cyclic phosphorothioate; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; D016202:N-Methylaspartate; C054649:3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl)-4-(3-hydroxypropyl)cyclohexanol; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D003620:Dantrolene; D000077285:Rimonabant; D002118:Calcium