Inhibition of excessive neuronal apoptosis by the calcium antagonist amlodipine and antioxidants in cerebellar granule cells.
Neuronal cell death as a result of apoptosis is associated with cerebrovascular stroke and various neurodegenerative disorders. Pharmacological agents that maintain normal intracellular Ca2+ levels and inhibit cellular oxidative stress may be effective in blocking abnormal neuronal apoptosis. In this study, a spontaneous (also referred to as age-induced) model of apoptosis consisting of rat cerebellar granule cells was used to evaluate the antiapoptotic activities of voltage-sensitive Ca2+ channel blockers and various antioxidants. The results of these experiments demonstrated that the charged, dihydropyridine Ca2+ channel blocker amlodipine had very potent neuroprotective activity in this system, compared with antioxidants and neutral Ca2+ channel blockers (nifedipine and nimodipine). Within its effective pharmacological range (10-100 nM), amlodipine attenuated intracellular neuronal Ca2+ increases elicited by KCl depolarization but did not affect Ca2+ changes triggered by N-methyl-D-aspartate receptor activation. Amlodipine also inhibited free radical-induced damage to lipid constituents of the membrane in a dose-dependent manner, independent of Ca2+ channel modulation. In parallel experiments, spontaneous neuronal apoptosis was inhibited in dose- and time-dependent manners by antioxidants (U-78439G, alpha-tocopherol, and melatonin), nitric oxide synthase inhibitors (N-nitro-L-arginine and N-nitro-D-arginine), and a nitric oxide chelator (hemoglobin) in the micromolar range. These results suggest that spontaneous neuronal apoptosis is associated with excessive Ca2+ influx, leading to further intracellular Ca2+ increases and the generation of reactive oxygen species. Agents such as amlodipine that block voltage-sensitive Ca2+ channels and inhibit cellular oxidative stress may be effective in the treatment of cerebrovascular stroke and neurodegenerative diseases associated with excessive apoptosis.
Mason
R P
RP
Cardiovascular and Pulmonary Research Institute, MCP-Hahnemann School of Medicine, Allegheny University of the Health Sciences, Pittsburgh, Pennsylvania 15212-4772, USA.
Leeds
P R
PR
Jacob
R F
RF
Hough
C J
CJ
Zhang
K G
KG
Mason
P E
PE
Chuang
D M
DM
D017311:Amlodipine / Q000494:pharmacology*; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000502:physiology; D002478:Cells, Cultured; D016922:Cellular Senescence / Q000187:drug effects; D002531:Cerebellum / Q000166:cytology; D002843:Chromatin / Q000378:metabolism; D053938:DNA Fragmentation / Q000187:drug effects; D006454:Hemoglobins / Q000494:pharmacology; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology; D015227:Lipid Peroxidation / Q000187:drug effects / Q000502:physiology; D008081:Liposomes / Q000187:drug effects / Q000502:physiology; D008550:Melatonin / Q000494:pharmacology; D009474:Neurons / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D009553:Nimodipine / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D019335:Nitroarginine / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014810:Vitamin E / Q000494:pharmacology
D000975:Antioxidants; D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002843:Chromatin; D006454:Hemoglobins; D008081:Liposomes; D014810:Vitamin E; D017311:Amlodipine; D019335:Nitroarginine; D009569:Nitric Oxide; D009553:Nimodipine; D008550:Melatonin