title: Cannabinoid receptor type 1 protects nigrostriatal dopaminergic neurons against MPTP neurotoxicity by inhibiting microglial activation.
abstract: This study examined whether the cannabinoid receptor type 1 (CB(1)) receptor contributes to the survival of nigrostriatal dopaminergic (DA) neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson's disease. MPTP induced significant loss of nigrostriatal DA neurons and microglial activation in the substantia nigra (SN), visualized with tyrosine hydroxylase or macrophage Ag complex-1 immunohistochemistry. Real-time PCR, ELISA, Western blotting, and immunohistochemistry disclosed upregulation of proinflammatory cytokines, activation of microglial NADPH oxidase, and subsequent reactive oxygen species production and oxidative damage of DNA and proteins in MPTP-treated SN, resulting in degeneration of DA neurons. Conversely, treatment with nonselective cannabinoid receptor agonists (WIN55,212-2 and HU210) led to increased survival of DA neurons in the SN, their fibers and dopamine levels in the striatum, and improved motor function. This neuroprotection by cannabinoids was accompanied by suppression of NADPH oxidase reactive oxygen species production and reduced expression of proinflammatory cytokines from activated microglia. Interestingly, cannabinoids protected DA neurons against 1-methyl-4-phenyl-pyridinium neurotoxicity in cocultures of mesencephalic neurons and microglia, but not in neuron-enriched mesencephalic cultures devoid of microglia. The observed neuroprotection and inhibition of microglial activation were reversed upon treatment with CB(1) receptor selective antagonists AM251 and/or SR14,716A, confirming the involvement of the CB(1) receptor. The present in vivo and in vitro findings clearly indicate that the CB(1) receptor possesses anti-inflammatory properties and inhibits microglia-mediated oxidative stress. Our results collectively suggest that the cannabinoid system is beneficial for the treatment of Parkinson's disease and other disorders associated with neuroinflammation and microglia-derived oxidative damage.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Kyung Hee University, Seoul 130-701, Korea.
authors.forename: Young C
authors.initials: YC
authors.lastname: Chung
authors.forename: Eugene
authors.initials: E
authors.lastname: Bok
authors.forename: Sue H
authors.initials: SH
authors.lastname: Huh
authors.forename: Ju-Young
authors.initials: JY
authors.lastname: Park
authors.forename: Sung-Hwa
authors.initials: SH
authors.lastname: Yoon
authors.forename: Sang R
authors.initials: SR
authors.lastname: Kim
authors.forename: Yoon-Seong
authors.initials: YS
authors.lastname: Kim
authors.forename: Sungho
authors.initials: S
authors.lastname: Maeng
authors.forename: Sung Hyun
authors.initials: SH
authors.lastname: Park
authors.forename: Byung K
authors.initials: BK
authors.lastname: Jin
mesh_terms: D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000008:administration & dosage / Q000009:adverse effects* / Q000037:antagonists & inhibitors; D000818:Animals; D048588:Benzoxazines / Q000494:pharmacology; D002478:Cells, Cultured; D018920:Coculture Techniques; D003342:Corpus Striatum / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D015259:Dopamine Agents / Q000008:administration & dosage / Q000009:adverse effects; D013759:Dronabinol / Q000031:analogs & derivatives / Q000494:pharmacology; D006131:Growth Inhibitors / Q000502:physiology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D017628:Microglia / Q000187:drug effects* / Q000276:immunology* / Q000473:pathology; D009025:Morpholines / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009474:Neurons / Q000187:drug effects / Q000276:immunology / Q000473:pathology; D009498:Neurotoxins / Q000008:administration & dosage / Q000009:adverse effects*; D020734:Parkinsonian Disorders / Q000276:immunology / Q000473:pathology / Q000517:prevention & control; D043884:Receptor, Cannabinoid, CB1 / Q000378:metabolism / Q000502:physiology*; D013378:Substantia Nigra / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism
chemical_list: D048588:Benzoxazines; D015259:Dopamine Agents; D006131:Growth Inhibitors; D009025:Morpholines; D009281:Naphthalenes; D009498:Neurotoxins; D043884:Receptor, Cannabinoid, CB1; C070417:(3R)-((2,3-dihydro-5-methyl-3-((4-morpholinyl)methyl)pyrrolo-(1,2,3-de)-1,4-benzoxazin-6-yl)(1-naphthalenyl))methanone; D013759:Dronabinol; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine; C062018:HU 211