Calcium signals activated by arachidonic acid in embryonic chick ciliary ganglion neurons.
Arachidonic acid (AA, 20:4) has been reported to modulate a variety of calcium-permeable ionic channels, both in the plasma membrane and in the endoplasmic reticulum. We have studied the effects of AA on calcium signaling in a well-characterized model of developing peripheral neurons, embryonic chick ciliary ganglion neurons in culture. When given at low non-micellar concentrations (5 microM), in the majority of cells AA directly activated a delayed and long-lasting increase in [Ca2+]i, involving both the cytoplasm and the nucleoplasm, that was completely reversed by abolition of extracellular calcium. Other fatty acids (FAs), either saturated like arachidic acid (20:0), or unsaturated like linoleic (18:2) and docosahexaenoic acid (22:6), shared its ability to activate calcium influx. This entry was not suppressed by voltage-dependent calcium channel inhibitors omega-conotoxin and nifedipine, by the voltage-independent calcium channel antagonist LOE-908, by pre-treatment with blockers of AA metabolic pathways or with pertussis toxin. The arachidonate-activated calcium pathway was permeable to Mn2+ and blocked by La3+, Gd3+ and Ni2+. In a neuronal subpopulation, AA at the same concentration was also able to elicit calcium release from thapsigargin-sensitive intracellular stores; we provide evidence that cytochrome P450 epoxygenase is involved in this process.
Erriquez
Jessica
J
Dipartimento di Scienze Chimiche Alimentari Farmaceutiche e Farmacologiche, Università del Piemonte Orientale A. Avogadro, Novara, Italy.
Gilardino
Alessandra
A
Ariano
Paolo
P
Munaron
Luca
L
Lovisolo
Davide
D
Distasi
Carla
C
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling / Q000187:drug effects*; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002642:Chick Embryo; D005456:Fluorescent Dyes; D016257:Fura-2; D005726:Ganglia, Parasympathetic / Q000166:cytology / Q000196:embryology / Q000502:physiology*; D008670:Metals / Q000494:pharmacology; D018613:Microscopy, Confocal; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D013347:Subcellular Fractions / Q000378:metabolism
D005456:Fluorescent Dyes; D008670:Metals; D016718:Arachidonic Acid; D002118:Calcium; D016257:Fura-2