Takasuna M, Iwasaki T
Institute of Psychology, University of Tsukuba, Japan.
Yakubutsu Seishin Kodo. 1990 Jun;10(2):315-21.
At 2 and 4 days of age, rat pups were treated with 6-hydroxydopamine (6-OHDA; 70 micrograms, ivt) following desmethylimipramine (20 mg/kg, sc) pretreatment. Spontaneous activity test in a novel cage at 16 and 17 days of age revealed a sustained higher level of locomotor activity in 6-OHDA-treated rats, which was characterized by a deficit of habituation. For right/left discrimination learning trained from 18 days of age, "homing" was used as an reinforcer, i.e., pups could enter the goal area adjacent to home cage if they chose a predetermined correct arm of T-maze. Rats were trained 10 trials a day until they attained the learning criterion (at least 17 correct choices in 2 days). Thereafter, they were re-trained for the reversal learning to the criterion (at least 8 correct choices in a day). 6-OHDA-treated rats were required significantly more trials to attain the learning criterion both in the original and the reversal learnings. Biochemical assay confirmed a marked depletion of brain dopamine contents in striatum, cortex and midbrain with thalamus in 6-OHDA-treated rats. Therefore, the neonatal depletion of brain dopamine produced hyperactivity (habituation deficit) and a discrimination deficit during the developmental period.
在2日龄和4日龄时，对大鼠幼崽进行去甲丙咪嗪（20 mg/kg，皮下注射）预处理后，用6-羟基多巴胺（6-OHDA；70微克，脑室内注射）进行处理。在16日龄和17日龄时，在新笼子中进行的自发活动测试显示，6-OHDA处理的大鼠的运动活动水平持续较高，其特征是缺乏习惯化。对于从18日龄开始训练的左右辨别学习，“归巢”被用作强化物，即如果幼崽选择T型迷宫的预定正确臂，它们可以进入与家笼相邻的目标区域。大鼠每天训练10次，直到达到学习标准（2天内至少17次正确选择）。此后，它们再次训练以达到逆向学习标准（一天内至少8次正确选择）。6-OHDA处理的大鼠在原始学习和逆向学习中达到学习标准都需要显著更多的试验次数。生化分析证实，6-OHDA处理的大鼠纹状体、皮质、中脑以及丘脑的脑多巴胺含量明显减少。因此，新生儿期脑多巴胺的耗竭在发育期间产生了多动（习惯化缺陷）和辨别缺陷。
