[Strain differences of mice in learning of swimming behavior and effect of hemicholinium and vasopressin. Observation by a simple water maze apparatus].

In order to determine the strain differences in learning of swimming behavior and to study the influence of vasopressin or its derivatives on hemicholinium-3-induced impairment of water maze learning in mice, we designed a new apparatus using water maze which has three panels in small fish breeding water bath (L60 x W30 x H36 cm). In the first swimming, six strains of adult male mice, ICR, ddY, ddN, C3H/He, BALB/C and C57BL were subjected to learn swimming behavior twice a day for 6 d in a straight course. Only ICR, ddN, C57BL and BALB/C strain mice were chosen for the next experiment. In the second swimming, mice (ICR, ddN, C57BL, BALB/C) were swum in the water maze apparatus. Scopolamine-induced impairment of water maze learning was produced only in ICR, BALB/C mice, but not in C57BL and ddN strain, which was recovered by physostigmine. Amnesia was not obtained by intracerebroventricular injection (i.c.v.) of cycloheximide and AlCl3 in mice (ICR). Hemicholinium-induced amnesia was improved by vasopressin and desmopressin. Lysine-vasopressin and oxytocin were without affecting hemicholinium-induced amnesia. Pretreatment with a vasopressin antagonist, ([1-(beta-mercapto-beta,beta-cyclopenta-methylene propionic acid), 2-(o-methyl)tyrosine arginine]-vasopressin) resulted in a reversible effect on the improvement of hemicholinium-induced amnesia by vasopressin. Of four different strain mice, ICR mice were the most preferable to the presently used test. They were also more responsive to hemicholinium and vasopressin than the other strains. These results suggest that the simple water maze apparatus may be useful for a pre-examination of nootropics or a study of learning of swimming behavior in mice.