MEK inhibitor PD98059 acutely inhibits synchronized spontaneous Ca2+ oscillations in cultured hippocampal networks.
OBJECTIVE
To investigate the changes in synchronized spontaneous Ca2+ oscillations induced by mitogen-activated protein kinase kinase (MEK) inhibitor PD98059 at different concentrations in cultured hippocampal network.


METHODS
Hippocampal neurons in culture for 1-2 weeks were used for this study. Spontaneous synaptic activities of these hippocampal neurons were examined by Ca2+ imaging using calcium-sensitive dye. MEK inhibitor PD98059 (10, 30, and 60 micromol/L) and SB202474 (10 and 60 micromol/L), a negative control for mitogen-activated protein kinase (MAPK) cascade study, were applied to the cells under the microscope while imaging was taking place.


RESULTS
PD98059 at a lower concentration of 10 micromol/L had little effect on the Ca2+ oscillation. At the higher concentration of 30 micromol/L, 5 min after application of PD98059, the spike frequency was decreased to 25.38% +/-7.40% (mean+/-SEM, n=16, P<0.01 vs medium control) of that of the control period. At an even higher concentration of 60 micromol/L, 5 min after application of PD98059, the spike frequency was decreased to 14.53%+/-5.34% (mean+/-SEM, n=16, P< 0.01 vs medium control) of that of the control period. The spike amplitude underwent a corresponding decrease. However, the negative control SB202474 at concentrations of 10 and 60 micromol/L had little inhibition effect on the Ca2+ oscillation.


CONCLUSIONS
These results indicate that PD98059 inhibits synchronized spontaneous Ca2+ oscillation through inhibition of MEK, which hints that the MAPK cascade is required to maintain synchronized spontaneous Ca2+ oscillation.
Rui
Yan-fang
YF
Department of Biological Science and Biotechnology, State Key Laboratory of Biomembrane and Membrane Biotechnology, Tsinghua University, Beijing 100084, China.
Sun
Zhao-hui
ZH
Gu
Jia-ping
JP
Shen
Zhong-hua
ZH
He
Xiang-ping
XP
Xie
Zuo-ping
ZP
D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects*; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D005333:Fetus; D005419:Flavonoids / Q000008:administration & dosage / Q000494:pharmacology*; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects*; D007093:Imidazoles / Q000494:pharmacology; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors*; D009474:Neurons / Q000166:cytology / Q000187:drug effects; D051381:Rats
D005419:Flavonoids; D007093:Imidazoles; C465539:SB202494; D020929:Mitogen-Activated Protein Kinase Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one