Comparison of CD-1 and ICR mouse strains for impulsivity in the enriched cross-maze test: Effects of atomoxetine

Abstract

Introduction: Attention deficit hyperactivity disorder (ADHD) in children and adults is a neuropsychiatric condition that is characterized by difficulty sustaining attention and behavioral impulsivity. It is one of the problems of modern medicine requiring development of appropriate treatments and valid animal models. Previously, we have developed a model of the enriched cross-maze test suitable for express-evaluation of attention deficiency in rodents. Recently, we have also revealed that while employing spontaneously hypertensive rats it is possible to estimate impulsivity indices in the test. The present study is aimed at evaluation of the impulsivity indicators in the enriched cross-maze test employing mice of outbred CD-1 and ICR strains, belonging to different breeding cores.

Materials and Method: Adult male mice of the both outbred CD-1 (n=199) and ICR (n=148) strains were used in the study. Atomoxetine (3 mg/kg) as the drug of choice for ADHD was administered intraperitoneally once daily for 6 consecutive days.

Results and Discussion: Frequency distribution of the impulsivity index obtained from mice of both strains had a clear bimodal shape that statistically significantly differed from the normal distribution. The outcome indicates existence of subpopulations of individuals with high and low impulsivity. In inattentive mice, the subchronic atomoxetine administration selectively improved impulsivity indicators in the second enriched cross-maze test.

Conclusion: The enriched cross-maze test may be useful in neurobiology studies of ADHD and for screening new drug candidates for the ADHD treatment.

 

Graphical Abstract