Acute Administration of Imipramine and Citalopram Increases Activity of Striatal-Enriched Tyrosine Protein Phosphatase (STEP) in Brain of Zebrafish Danio rerio.

Effects of acute treatment with antidepressant drugs, imipramine and citalopram, on behavior and activity of striatal-enriched tyrosine protein phosphatase (STEP) in the whole brain of zebrafish Danio rerio were studied. Mature zebrafish were exposed for 3 h to water (control) or to solutions of 0.25, 0.5, or 1 mg/liter of imipramine or citalopram, and then their behavior was studied in novel tank test. STEP activity was assayed in the brain of animals by the difference between the rates of transformation of p-nitrophenyl phosphate to 4-nitrophenol in the absence or presence of a selective STEP inhibitor. In novel tank test, imipramine and citalopram reduced locomotor activity and increased freezing time; at this, imipramine increased the total time spent in top of the tank. Citalopram (all concentrations) and imipramine (0.5 and 1 mg/liter) increased STEP activity in zebrafish brain.