抄録
Prostaglandin E2 (PGE2), one of the major lipid mediators produced by the arachidonic acid cascade, is involved in various physiological effects. We demonstrated previously that PGE2 suppressed cell proliferation and promoted neurite outgrowth, a morphological marker of neuronal cell differentiation, in NSC-34 cells, a hybrid cell line produced by fusion of motor neuron-enriched spinal cord cells with mouse neuroblastoma cells and that E-prostanoid receptor 2 subtype plays a role in the PGE2-induced differentiation of NSC-34 cells. However, electrophysiological characteristics of differentiated NSC-34 cells by PGE2 still remains to be elucidated. In the present study, we compared the electrophysiological properties of the NSC-34 cells differentiated by PGE2 to those by retinoic acid (RA) using whole-cell patch clamp techniques.
NSC-34 cells were maintained in DMEM containing 10% fetal bovine serum (FBS). For cell differentiation, NSC-34 cells were treated with 30 µM PGE2 in DMEM containing 10% FBS for 2 days or with 10 µM RA in DMEM/F12 containing 0.5% FBS and 1% MEM non-essential amino acid for 7 days. For the patch clamp recording, grass electrodes (5-9 MΩ) filled with an intracellular solution were used for whole-cell patch clamp with a standard extracellular solution (ECS).
Significant increases in membrane capacitance and the inward current density recorded under voltage-clamp conditions were observed in NSC-34 cells subjected to PGE2- as well as RA-induced differentiation. There were no significant differences in these parameters between PGE2- and RA-treated NSC-34 cells. Inward currents of PGE2- and RA-treated NSC-34 cells were completely suppressed by switching the standard ECS to Na+-free ECS or by the addition of 1 µM tetrodotoxin into the standard ECS. Switching the standard ECS to Ca2+-free ECS tended to reduce the amplitude of PGE2- and RA-treated NSC-34 cells. Under the current-clamp condition, action potentials were observed in NSC-34 cells subjected to PGE2- and RA-induced differentiation.
These results suggest that PGE2 induces differentiation of NSC-34 cells with neuron-like features to generate action potentials and that Na+ channels play an important role in neuron-like features in differentiated NSC-34 cells.
