Fulford A J, Marsden C A
CNS Neuropharmacology Group, Department of Physiology, Queen's Medical Centre, Nottingham, England.
J Neurochem. 1998 Jan;70(1):384-90. doi: 10.1046/j.1471-4159.1998.70010384.x.
Intracerebral microdialysis in conjunction with HPLC coupled to electrochemical detection was used to investigate the effect of isolation-rearing in the rat on extracellular dopamine (DA) and its metabolites in vivo, in the shell region of the nucleus accumbens, in response to footshock and in relation to a conditioned emotional response. Male Lister hooded rats were reared from weaning for 6-8 weeks in either social isolation or groups of five. In the training phase, rats were exposed to a novel environment for 10 min where they experienced mild footshock. Footshock caused an immediate increase in basal extracellular DA levels in both rearing groups relative to control rats. However, the increase in extracellular DA was prolonged in the case of the isolation-reared rats and significantly greater than in group-reared rats. Exposure to the novel environment without shock (control groups) did not significantly alter basal extracellular DA in the nucleus accumbens shell; 140 min later rats were returned to the testing box (contextual stimulus) without receiving footshock. The contextual stimulus increased basal extracellular DA in the nucleus accumbens of both groups of rats with respect to controls; however, this increase was significantly greater and more prolonged in isolates. Extracellular levels of the metabolites 3,4-dihydroxyphenylacetic acid and homovanillic acid did not differ between isolation- and group-reared rats, and they were not significantly affected by either footshock or the contextual stimulus. These results suggest that exposure to footshock and a contextual stimulus are associated with increases in basal extracellular DA levels in the nucleus accumbens shell. The results also support evidence in favour of an isolation-induced enhancement in dopaminergic activity in the nucleus accumbens, which probably underlies aspects of the behavioural syndrome associated with isolation.
采用脑内微透析技术结合高效液相色谱-电化学检测法，研究大鼠隔离饲养对伏隔核壳区细胞外多巴胺（DA）及其代谢产物的影响，观察其在遭受足部电击时以及与条件性情绪反应相关的体内变化。雄性利斯特戴帽大鼠自断奶后，分别在社会隔离环境或五只一组的群体环境中饲养6 - 8周。在训练阶段，大鼠被置于新环境中10分钟，期间遭受轻度足部电击。与对照大鼠相比，足部电击使两个饲养组的基础细胞外DA水平立即升高。然而，隔离饲养大鼠的细胞外DA升高持续时间更长，且显著高于群体饲养大鼠。暴露于无电击的新环境（对照组）并未显著改变伏隔核壳区的基础细胞外DA水平；140分钟后，大鼠在未接受足部电击的情况下被放回测试箱（情境刺激）。情境刺激使两组大鼠伏隔核的基础细胞外DA相对于对照组均有所升高；然而，这种升高在隔离饲养大鼠中更为显著且持续时间更长。隔离饲养和群体饲养大鼠的代谢产物3,4 - 二羟基苯乙酸和高香草酸的细胞外水平无差异，且它们均未受到足部电击或情境刺激的显著影响。这些结果表明，暴露于足部电击和情境刺激与伏隔核壳区基础细胞外DA水平升高有关。结果还支持了隔离诱导伏隔核多巴胺能活性增强的证据，这可能是与隔离相关行为综合征某些方面的基础。
