Dopamine release in PC12 cells is mediated by Ca(2+)-dependent production of ceramide via sphingomyelin pathway.
A presynaptic membrane disturbance is an essential process for the release of various neurotransmitters. Ceramide, which is a tumor suppressive lipid, has been shown to act as a channel-forming molecule and serve as a precursor of ceramide-1-phosphate, which can disturb the cellular membrane. This study found that while permeable ceramide increases the rate of dopamine release in the presence of a Ca(2+)-ionophore, A23187, permeable ceramide-1-phosphate provoked its release even without the ionophore. The treatment of PC12 cells with the ionophore at concentrations < 2 microM produced ceramide via the sphingomyelin (SM) pathway with a concomitant release of dopamine, and no cell damage was observed. The addition of a Ca(2+) chelator, EGTA, to the medium inhibited the increase in the release of both the ceramide and dopamine. This suggests that ceramide might be produced by Ca(2+) and is implicated in the membrane disturbance associated with the release of dopamine as a result of its conversion to ceramide-1-phosphate. Consistent with these results, this study detected a membrane-associated and neutral pH optimum sphingomyelinase (SMase) whose activity was increased by Ca(2+). Together, these results demonstrate that ceramide can be produced via the activation of a neutral form of SMase through Ca(2+), and is involved in the dopamine release in concert with Ca(2+).
Jeon
Hyung Jun
HJ
Department of Environmental and Health Chemistry, College of Pharmacy, Chung-Ang University, Dongjakgu, Seoul, Korea.
Lee
Dong Hoon
DH
Kang
Mi Sun
MS
Lee
Mi-Ock
MO
Jung
Kwang Mook
KM
Jung
Sung Yun
SY
Kim
Dae Kyong
DK
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability; D002518:Ceramides / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D009474:Neurons / Q000166:cytology / Q000378:metabolism*; D016716:PC12 Cells; D017729:Presynaptic Terminals / Q000378:metabolism; D051381:Rats; D013108:Sphingomyelin Phosphodiesterase / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism*
D002518:Ceramides; D007476:Ionophores; D013109:Sphingomyelins; D000001:Calcimycin; D013108:Sphingomyelin Phosphodiesterase; D002118:Calcium; D004298:Dopamine