Effect of potassium channel modulators in mouse forced swimming test

1 The effect of intracerebroventricular (i.c.v.) administration of different potassium channel blockers (tetraethylammonium, apamin, charybdotoxin, gliquidone), potassium channel openers (pinacidil, minoxidil, cromakalim) and aODN to mKv1.1 on immobility time was evaluated in the mouse forced swimming test, an animal model of depression. 2 Tetraethylammonium (TEA; 5 mu g per mouse i.c.v.), apamin (3 ng per mouse i.c.v.), charybdotoxin (1 mu g per mouse i.c.v.) and gliquidone (6 mu g per mouse i.c.v.) administered 20 min before the test produced anti-immobility comparable to that induced by the tricyclic antidepressants amitriptyline (15 mg kg(-1) s.c.) and imipramine (30 mg kg(-1) s.c.). 3 By contrast pinacidil (10-20 mu g per mouse i.c.v.), minoxidil (10-20 mu g per mouse i.c.v.) and cromakalim (20-30 mu g per mouse i.c.v.) increased immobility time when administered in the same experimental conditions. 4 Repeated administration of an antisense oligonucleotide (aODN) to the mKv1.1 gene (1 and 3 nmol per single i.c.v. injection) produced a dose-dependent increase in immobility time of mice 72 h after the last injection. At day 7, the increasing effect produced by aODN disappeared. A degenerate mKv1.1 oligonucleotide (dODN), used as control, did not produce any effect in comparison with saline- and vector-treated mice. 5 At the highest effective dose, potassium channels modulators and the mKv1.1 aODN did not impair motor coordination, as revealed by the rota rod test, nor did they modify spontaneous motility as revealed by the Animex apparatus. 6 These results suggest that modulation of potassium channels plays an important role in the regulation of immobility time in the mouse forced swimming test.