title: The biphasic effect of phospholipase A2 inhibitors on axon elongation.
abstract: We have analyzed changes in axon elongation rate in vitro induced by three different phospholipase A2 inhibitors, namely, bromophenacyl bromide (BPB), quinacrine and Sr2+. Spinal ganglia were obtained from 19.5-day-old rat fetuses and explanted onto polyornithine substrata. Axon length was measured at 1, 2 and 3 days in vitro (d.i.v.). We have previously shown that BPB added at 5 hr in vitro (h.i.v.) modifies the structure of growth cones and inhibits or promotes axon elongation according to its concentration. Now, we have observed that 0.5 x 10(-6) M BPB also stimulates axon elongation when added at 1 d.i.v. Culture media with different Ca2+ concentrations were used to test Sr2+ added at 1 d.i.v. In 2.3 mM Ca2+ only an inhibitory effect was observed with 8 mM Sr2+. On the other hand, in 0.3 mM Ca2+, axon growth was stimulated by 0.6-1.2 mM Sr2+ but inhibited by 6 mM Sr2+. Quinacrine, added at 5 h.i.v. was inhibitory at 10(-5) M and showed no effects at 10(-6) M. However, after washing quinacrine, normal elongation rate was recovered by those previously treated with 10(-5) M and axon growth was enhanced in those treated with 10(-6) M. Since three different phospholipase A2 inhibitors, tested in different situations, produce a similar biphasic effect on axon elongation rate, we postulate that this enzymatic activity is involved in the motility of axon growth cones.
authors.affiliation: Instituto de Neurobiologia, Buenos Aires, Argentina.
authors.forename: A
authors.initials: A
authors.lastname: Suburo
authors.forename: C
authors.initials: C
authors.lastname: Cei de Job
mesh_terms: D000098:Acetophenones / Q000494:pharmacology; D000818:Animals; D001369:Axons / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005727:Ganglia, Spinal / Q000166:cytology* / Q000187:drug effects; D010740:Phospholipases / Q000502:physiology*; D010741:Phospholipases A / Q000378:metabolism / Q000502:physiology*; D054467:Phospholipases A2; D011796:Quinacrine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D013324:Strontium / Q000494:pharmacology
chemical_list: D000098:Acetophenones; D004791:Enzyme Inhibitors; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2; D011796:Quinacrine; C006821:4-bromophenacyl bromide; D013324:Strontium