MacMillan S J, Mark M A, Duggan A W
Department of Preclinical Veterinary Sciences, Royal (Dick) School of Veterinary Studies, University of Edinburgh, Summerhall, Edinbúrgh EH9 1QH, UK.
Brain Res. 1998 May 25;794(1):127-36. doi: 10.1016/s0006-8993(98)00223-6.
Microprobes bearing immobilized antibodies to the carboxy-terminus of beta-endorphin were used to study the release of beta-endorphin in the urethane anaesthetized rat following electrical stimulation of the ipsilateral arcuate nucleus. The microprobes were inserted through the cerebral hemisphere, the superior colliculus and the midbrain periaqueductal grey. Since such microprobes detect extracellular molecules along their entire length they give information on the persistence and spread of compounds following release. Little immunoreactive-beta-endorphin was detected in the areas of brain sampled during electrical stimulation of arcuate nucleus but a remarkable spread throughout the midbrain and cerebral cortex occurred within 30 min of the cessation of stimulation. The results suggest that although beta-endorphin-containing fibres are absent in many parts of the brain, this neuropeptide can access receptors in these sites and it is not necessary for release to be directly adjacent to opiate receptors. As such it is important evidence supporting the hypothesis of volume transmission as a means of neuronal communication. The results also suggest that an important mechanism of the transport of beta-endorphin is the cerebrospinal fluid.
携带固定有针对β-内啡肽羧基末端抗体的微探针，被用于研究在对同侧弓状核进行电刺激后，乌拉坦麻醉大鼠体内β-内啡肽的释放情况。微探针穿过大脑半球、上丘和中脑导水管周围灰质插入。由于此类微探针沿其全长检测细胞外分子，它们能提供有关化合物释放后持久性和扩散情况的信息。在对弓状核进行电刺激期间所采集的脑区中，几乎检测不到免疫反应性β-内啡肽，但在刺激停止后的30分钟内，其在整个中脑和大脑皮层出现了显著扩散。结果表明，尽管大脑许多部位不存在含β-内啡肽的纤维，但这种神经肽可作用于这些部位的受体，且释放并不一定直接邻近阿片受体。因此，这是支持容积传递作为神经元通讯方式这一假说的重要证据。结果还表明，β-内啡肽运输的一个重要机制是脑脊液。
