Exposito I, Mora F, Oaknin S
Department of Biochemistry and Molecular Biology, Faculty of Biology, University of La Laguna, Tenerife, Spain.
Neuroreport. 1995 Mar 7;6(4):661-5. doi: 10.1097/00001756-199503000-00019.
The aim of the present study was to investigate the role of melatonin as neuromodulator. For that, the effects of melatonin on the extracellular concentrations of excitatory amino acids, glutamic and aspartic acids, were investigated in the anterior hypothalamus and parieto-temporal cortex of the conscious rat using an intracerebral perfusion system. Melatonin at doses of 250 nM and 1 microM produced no effects on extracellular glutamate and aspartate concentrations in these two areas of the brain. Since amphetamine releases dopamine we perfused melatonin into the anterior hypothalamus and parieto-temporal cortex after a previous injection of amphetamine. Interestingly, we found a release of glutamic acid (p < 0.01) and aspartic acid (p < 0.01) produced by melatonin only when the increase (157%) of the extracellular dopamine concentration evoked by amphetamine was inhibited by melatonin in the anterior hypothalamus. The possibility is discussed of melatonin exerting its effects when the dopaminergic system is activated.
本研究的目的是调查褪黑素作为神经调节剂的作用。为此，使用脑内灌注系统，在清醒大鼠的下丘脑前部和顶颞叶皮质中研究了褪黑素对兴奋性氨基酸（谷氨酸和天冬氨酸）细胞外浓度的影响。250 nM和1 microM剂量的褪黑素对大脑这两个区域的细胞外谷氨酸和天冬氨酸浓度没有影响。由于苯丙胺会释放多巴胺，我们在先前注射苯丙胺后将褪黑素灌注到下丘脑前部和顶颞叶皮质中。有趣的是，我们发现仅当下丘脑前部中苯丙胺引起的细胞外多巴胺浓度增加（157%）被褪黑素抑制时，褪黑素才会导致谷氨酸（p < 0.01）和天冬氨酸（p < 0.01）的释放。文中讨论了多巴胺能系统被激活时褪黑素发挥其作用的可能性。
