Green Thomas A, Cain Mary E, Thompson Michael, Bardo Michael T
Department of Psychology, University of Kentucky, 115 Kastle Hall, Lexington, KY 40506, USA.
Psychopharmacology (Berl). 2003 Nov;170(3):235-241. doi: 10.1007/s00213-003-1538-3. Epub 2003 Jul 4.
Previous research has determined that rats reared in an enriched condition (EC) are more sensitive to the effects of acute systemic amphetamine than rats raised in an impoverished condition (IC).
The present experiments examined the effect of environmental enrichment on locomotor activity following repeated injections of nicotine. Experiment 1 assessed differences in locomotor activity in EC and IC rats and experiment 2 assessed differences between EC rats and rats housed in pairs without novel objects or daily handling (social condition; SC) to determine whether enrichment causes changes beyond that of social contact alone.
In experiment 1, EC and IC rats were treated with saline, 0.2 mg/kg or 0.8 mg/kg nicotine, and locomotor activity was assessed for 60 min. Nicotine-induced activity was measured every 48 h for a total of eight sessions. All rats were challenged with 0.8 mg/kg nicotine on session 9. In experiment 2, EC and SC rats were treated with saline or 0.2 mg/kg nicotine, and locomotor activity was assessed using the same regimen as in experiment 1.
In experiment 1, EC rats exhibited less sensitivity than IC rats to the psychostimulant effect of nicotine upon both acute and repeated administration. On the nicotine challenge session (session 9), EC rats were again less sensitive to the hyperactive effects of nicotine. In experiment 2, EC rats were also less sensitive than SC rats to nicotine-induced hyperactivity across repeated injections.
These results suggest that environmental enrichment during development reduces the stimulant effect of nicotine.
先前的研究已确定，在丰富环境（EC）中饲养的大鼠比在贫瘠环境（IC）中饲养的大鼠对急性全身性苯丙胺的影响更敏感。
本实验研究了环境丰富对重复注射尼古丁后运动活动的影响。实验1评估了EC组和IC组大鼠运动活动的差异，实验2评估了EC组大鼠与成对饲养且无新物体或日常处理的大鼠（社交环境；SC）之间的差异，以确定丰富环境是否会导致超出单纯社交接触的变化。
在实验1中，EC组和IC组大鼠分别接受生理盐水、0.2mg/kg或0.8mg/kg尼古丁处理，并评估60分钟的运动活动。每48小时测量一次尼古丁诱导的活动，共进行八次实验。所有大鼠在第9次实验时接受0.8mg/kg尼古丁刺激。在实验2中，EC组和SC组大鼠分别接受生理盐水或0.2mg/kg尼古丁处理，并采用与实验1相同的方案评估运动活动。
在实验1中，无论是急性给药还是重复给药，EC组大鼠对尼古丁的精神兴奋作用的敏感性均低于IC组大鼠。在尼古丁刺激实验（第9次实验）中，EC组大鼠对尼古丁的多动效应同样不敏感。在实验2中，在重复注射过程中，EC组大鼠对尼古丁诱导的多动也比SC组大鼠不敏感。
这些结果表明，发育期间的环境丰富会降低尼古丁的刺激作用。
