Comparison of the validity of the use of the spontaneously hypertensive rat as a model of attention deficit hyperactivity disorder in males and females.

The spontaneously hypertensive rat (SHR) is a commonly used and well-studied rodent model of attention deficit hyperactivity disorder (ADHD). Sex differences in the cognitive symptoms of ADHD are reported. However, the female SHR rat is much less studied than its male counterpart. The goal of the current study was to assess the validity of the SHR rodent model of ADHD by examining attentional performance, inhibitory control, and hyperactivity in both male and female SHR rats. Adult SHR and control Wistar-Kyoto rats were trained on the 5-choice serial reaction time task, a self-paced test of attention and inhibitory control. This task requires animals to identify the location of a brief light stimulus among five possible locations under several challenging conditions. Analyses of percent correct revealed that attentional performance in SHR females was not significantly different from control females, whereas attentional performance in SHR males was significantly different from control males. Analyses of the number of premature responses revealed that SHR rats made more inhibitory control errors than did control rats and that this decrease in inhibitory control was present in both SHR males and females. Analyses of activity in the open field revealed that SHR rats were more hyperactive than were control rats and that this increased hyperactivity was present in both SHR males and females. The current findings have implications for the study of sex differences in ADHD and for the use of SHR rats as a model of ADHD in females.