Abstract: Objective To study the brain cell injuries and behavioral changes of newborn rats with kernicterus. Methods Twenty-five 5-day-old Sprague-Dawley rats were divided into control group (n=11) and model group (n=14) radomly. The model group was injected with bilirubin solution 10 μg/g in the cisterna magna, while the control group was injected with equal volume of normal saline. The neurobehavioral changes were observed and the body mass were recorded. TUNEL staining was used to check the apoptosis of striatal nerve cells of basal ganglia in the model group (n=3) on the first day after modeling. The remaining rats were assessed by gait analysis and beam-walking test 19 days after birth, and Morris water maze test was performed 30 days after birth. Results The model group showed apparently abnormal neurobehavioral changes, such as clenched fists, opisthotonos and the body mass were significantly lower in the model group than in the control group (F>27.707, P<0.001). TUNEL staining showed striatal nerve cells apoptosis in the model group. For the gait analysis, the step lengths of both hind legs were shorter (t>4.129, P<0.01), and the difference of step length was longer (t=-4.415, P<0.001) in the model group than in the control group, however, there was no significantly difference in the step width between two groups (t=0.462, P=0.649). For the beam-walking test, the score was lower in the model group than in the control group (t=-3.644, P=0.004). For the Morris water maze test, the escape latency was longer (F>6.206, P<0.05), and the number of crossing platform was less (t=3.297, P=0.004) in the model group than in the control group. Conclusion The newborn rats' model of kernicterus showed deficits in multiple motor functions and learning and memory ability, which could be assessed by gait analysis, beam-walk test and Morris water maze test, respectively.

Key words: kernicterus, gait analysis, beam-walking test, Morris water maze test, rats