Inhibition of methamphetamine-induced apoptosis by the calcium channel blocker verapamil in rat cerebellar neurons.
OBJECTIVE
To study protective effects of verapamil on neurotoxicity induced by methamphetamine (MA) in rat cerebellar neuronal cells (R2 cells) and explore the possible mechanisms.


METHODS
MA neurotoxicity to R2 cells was examined by MTT reduction and LDH leakage assays. Using flow cytometer and agarose gel electrophoresis, apoptosis induced by MA in R2 cells was observed. The effects of verapamil on neurotoxicity and apoptosis induced by MA in R2 cells were determined.


RESULTS
(1) Incubation of the R2 cells with MA (0.25-3.00 mmol/L) for 48 h or 60 h concentration-dependently increased the LDH content in the extra-cellular bathing medium by 48.2%-89.3% and 62.5%-97.3%, respectively. Exposure to MA elicited the apoptotic DNA peak of the R2 cells (i.e. sub-G1-peak) in a concentration- and time-dependent manner by the use of flow cytometer. Agarose gel electrophoresis showed a typical DNA laddering pattern. (2) Verapamil (0.5-5.0 micromol/L) reduced the number of dead cells and the LDH content in the extra-cellular bathing medium, ameliorated morphological changes, and inhibited apoptosis induced by MA in R2 cells.


CONCLUSIONS
These results suggest that verapamil has a neuroprotective effect on MA-induced apoptosis, and that L-type voltage dependent calcium channel may be involved in the neurotoxitic effect of MA.
National Institute on Drug Dependence, Peking University of Basic Medical School, Beijing 100083, China.
Jun-lan
JL
Zhou
Jian-hui
JH
Liang
Chang-ling
CL
Li
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D004305:Dose-Response Relationship, Drug; D004587:Electrophoresis, Agar Gel; D005434:Flow Cytometry; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008694:Methamphetamine / Q000633:toxicity*; D009474:Neurons / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000235:genetics; D013997:Time Factors; D014700:Verapamil / Q000494:pharmacology*
D002121:Calcium Channel Blockers; C409466:NR1 NMDA receptor; D018696:Neuroprotective Agents; D012333:RNA, Messenger; D016194:Receptors, N-Methyl-D-Aspartate; D008694:Methamphetamine; D014700:Verapamil; D007770:L-Lactate Dehydrogenase