8-(3-Chlorostyryl)caffeine may attenuate MPTP neurotoxicity through dual actions of monoamine oxidase inhibition and A2A receptor antagonism.
Caffeine and more specific antagonists of the adenosine A(2A) receptor recently have been found to be neuroprotective in the MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) model of Parkinson's disease. Here we show that 8-(3-chlorostyryl)caffeine (CSC), a specific A(2A) antagonist closely related to caffeine, also attenuates MPTP-induced neurotoxicity. Because the neurotoxicity of MPTP relies on its oxidative metabolism to the mitochondrial toxin MPP(+), we investigated the actions of CSC on striatal MPTP metabolism in vivo. CSC elevated striatal levels of MPTP but lowered levels of the oxidative intermediate MPDP(+) and of MPP(+), suggesting that CSC blocks the conversion of MPTP to MPDP(+) in vivo. In assessing the direct effects of CSC and A(2A) receptors on monoamine oxidase (MAO) activity, we found that CSC potently and specifically inhibited mouse brain mitochondrial MAO-B activity in vitro with a K(i) value of 100 nm, whereas caffeine and another relatively specific A(2A) antagonist produced little or no inhibition. The A(2A) receptor independence of MAO-B inhibition by CSC was further supported by the similarity of brain MAO activities derived from A(2A) receptor knockout and wild-type mice and was confirmed by demonstrating potent inhibition of A(2A) receptor knockout-derived MAO-B by CSC. Together, these data indicate that CSC possesses dual actions of MAO-B inhibition and A(2A) receptor antagonism, a unique combination suggesting a new class of compounds with the potential for enhanced neuroprotective properties.
Chen
Jiang-Fan
JF
Department of Neurology, Molecular Neurobiology Laboratory, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts 02129, USA. chenjf@bu.edu
Steyn
Salome
S
Staal
Roland
R
Petzer
Jacobus P
JP
Xu
Kui
K
Van Der Schyf
Cornelis J
CJ
Castagnoli
Kay
K
Sonsalla
Patricia K
PK
Castagnoli
Neal
N
Schwarzschild
Michael A
MA
D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine / Q000494:pharmacology*; D000818:Animals; D001921:Brain / Q000378:metabolism; D002110:Caffeine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D015259:Dopamine Agents / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004347:Drug Interactions; D007700:Kinetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008996:Monoamine Oxidase Inhibitors / Q000494:pharmacology*; D009474:Neurons / Q000187:drug effects*; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D013997:Time Factors
D015259:Dopamine Agents; D008996:Monoamine Oxidase Inhibitors; D043705:Receptor, Adenosine A2A; D018047:Receptors, Purinergic P1; C081320:8-(3-chlorostyryl)caffeine; D002110:Caffeine; D015632:1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine