Gresch P J, Sved A F, Zigmond M J, Finlay J M
Department of Behavioral Neuroscience, University of Pittsburgh, Pittsburgh 15260.
J Neurochem. 1994 Aug;63(2):575-83. doi: 10.1046/j.1471-4159.1994.63020575.x.
We examined whether prior exposure to chronic cold (17-28 days, 5 degrees C) alters basal or stress-evoked (30-min tail shock) catecholamine release in medial prefrontal cortex, nucleus accumbens, and striatum, using in vivo microdialysis. Basal norepinephrine (NE) concentrations in medial prefrontal cortex did not differ between chronically cold-exposed rats and naive control rats (2.7 +/- 0.3 vs. 2.5 +/- 0.2 pg/20 microliters respectively). Basal dopamine (DA) efflux in any of the brain regions was not significantly different between chronically cold-exposed rats and naive rats. However, a trend for lower basal DA efflux in the cold-exposed relative to naive rats was observed in medial prefrontal cortex (1.5 +/- 0.2 vs. 2.2 +/- 0.3 pg/20 microliters, respectively), nucleus accumbens (3.7 +/- 0.8 vs. 5.4 +/- 0.9 pg/20 microliters, respectively), and striatum (4.4 +/- 0.5 vs. 7.2 +/- 1.5 pg/20 microliters, respectively). In medial prefrontal cortex of rats previously exposed to cold, tail shock elicited a greater increase from baseline in both DA and NE efflux relative to that measured in naive rats (DA, 2.3 +/- 0.3 vs. 1.2 +/- 0.1 pg, respectively; NE, 3.8 +/- 0.4 vs. 1.4 +/- 0.2 pg, respectively). However, in nucleus accumbens or striatum of rats previously exposed to cold, the stress-induced increase in DA efflux was not significantly different from that of naive rats (nucleus accumbens, 1.8 +/- 0.7 vs. 1.5 +/- 0.3 pg, respectively; striatum, 1.9 +/- 0.4 vs. 2.6 +/- 0.7 pg, respectively). Thus, both cortical NE projections and cortically projecting DA neurons sensitize after chronic exposure to cold. In contrast, subcortical DA projections do not sensitize under these conditions.
我们使用体内微透析技术，研究了先前暴露于慢性寒冷环境（17 - 28天，5摄氏度）是否会改变内侧前额叶皮质、伏隔核和纹状体中基础或应激诱发（30分钟尾部电击）的儿茶酚胺释放。慢性寒冷暴露大鼠和未处理的对照大鼠内侧前额叶皮质中的基础去甲肾上腺素（NE）浓度没有差异（分别为2.7±0.3与2.5±0.2 pg/20微升）。慢性寒冷暴露大鼠和未处理大鼠在任何脑区的基础多巴胺（DA）流出均无显著差异。然而，在慢性寒冷暴露大鼠中，相对于未处理大鼠，内侧前额叶皮质（分别为1.5±0.2与2.2±0.3 pg/20微升）、伏隔核（分别为3.7±0.8与5.4±0.9 pg/20微升）和纹状体（分别为4.4±0.5与7.2±1.5 pg/20微升）中观察到基础DA流出有降低的趋势。在先前暴露于寒冷环境的大鼠内侧前额叶皮质中，尾部电击引起的DA和NE流出相对于未处理大鼠从基线的增加幅度更大（DA分别为2.3±0.3与1.2±0.1 pg；NE分别为3.8±0.4与1.4±0.2 pg）。然而，在先前暴露于寒冷环境的大鼠伏隔核或纹状体中，应激诱导的DA流出增加与未处理大鼠没有显著差异（伏隔核分别为1.8±0.7与1.5±0.3 pg；纹状体分别为1.9±0.4与2.6±0.7 pg）。因此，慢性暴露于寒冷后，皮质NE投射和皮质投射的DA神经元均会敏感化。相比之下，在这些条件下，皮质下DA投射不会敏感化。
