Sorg B A, Kalivas P W
Department of Veterinary and Comparative Anatomy, Washington State University, Pullman 99165-6520.
Neuroscience. 1993 Apr;53(3):695-703. doi: 10.1016/0306-4522(93)90617-o.
The interaction between cocaine and footshock stress was evaluated by determining changes in extracellular dopamine and metabolite levels by in vivo microdialysis in the medial prefrontal cortex. In the first experiment, rats were given one of three treatments: no pretreatment (naive); or five daily injections of cocaine (15 mg/kg, i.p.); or daily saline. Six to seven days later, animals had a microdialysis probe implanted into the medial prefrontal cortex and an acute 20-min footshock stress (0.45 mA/200 ms per s) or sham shock was delivered. The results showed that acute footshock in daily saline pretreated rats increased medial prefrontal cortex extracellular dopamine concentrations to 203% of baseline levels. In rats pretreated with daily cocaine, this stress-induced response was completely abolished and extracellular dopamine was reduced 38% below baseline levels by 100 min post-shock. Naive animals showed a response to footshock that was intermediate between cocaine and saline pretreated rats (156% of baseline). In the second experiment, rats were given either no pretreatment (naive) or five daily 20-min footshock treatments (as above) or daily sham shock. Six to seven days later, an acute cocaine or saline injection was given. In daily sham-pretreated rats, extracellular dopamine levels were increased to 500% of baseline in response to acute cocaine. Pretreatment with daily footshock significantly reduced the response to acute cocaine (216% of baseline). Naive rats showed an intermediate increase that was not significantly different from footshock-pretreated animals (265% of baseline). Locomotor activity measured concurrently with dialysis showed a non-significant trend towards enhanced activity in daily footshock animals.(ABSTRACT TRUNCATED AT 250 WORDS)
通过体内微透析法测定内侧前额叶皮质细胞外多巴胺及其代谢产物水平的变化，来评估可卡因与足部电击应激之间的相互作用。在第一个实验中，大鼠接受三种处理之一：无预处理（未处理组）；或连续五天注射可卡因（15毫克/千克，腹腔注射）；或每天注射生理盐水。六至七天后，将微透析探针植入动物的内侧前额叶皮质，并施加20分钟的急性足部电击应激（0.45毫安/每秒200毫秒）或假电击。结果显示，每天注射生理盐水预处理的大鼠，急性足部电击使内侧前额叶皮质细胞外多巴胺浓度增加至基线水平的203%。在用可卡因每日预处理的大鼠中，这种应激诱导的反应完全被消除，且电击后100分钟时细胞外多巴胺比基线水平降低了38%。未处理组动物对足部电击的反应介于可卡因和生理盐水预处理的大鼠之间（为基线水平的156%）。在第二个实验中，大鼠要么不做预处理（未处理组），要么接受五天每天20分钟的足部电击处理（如上所述），要么每天接受假电击。六至七天后，给予急性可卡因或生理盐水注射。在每天接受假电击预处理的大鼠中，急性注射可卡因后细胞外多巴胺水平增加至基线水平的500%。每天接受足部电击预处理显著降低了对急性可卡因的反应（为基线水平的216%）。未处理组大鼠的增加幅度介于两者之间，与足部电击预处理的动物无显著差异（为基线水平的265%）。与透析同时测量的运动活动显示，每天接受足部电击的动物活动增强的趋势不显著。（摘要截选至250词）
