Studies on developing and transplanted monoaminergic neurons using an "ultra-thin" slice preparation

为了研究移植单胺能神经元发育过程中功能成熟过程中可能发生的一系列事件，我们尝试在脑片制片中鉴定出活的单胺能神经元。用5，7-二羟色胺(5，7-DHT)类似物5，7-二羟色胺(5，7-DHT)处理幼鼠脑干薄片(厚80-100亩)。积累这种物质的神经元在紫外光下发出荧光。标记细胞在中缝核内的定位表明它们是5-羟色胺能神经元。在含有多巴胺神经元的黑质内未见标记细胞。细胞内记录还显示，标记神经元的反应与报道的5-羟色胺能中缝神经元一致；神经元的峰电位在时间过程中较慢，在其下降相显示一个驼峰，其膜时间常数较长。应用5，7-二羟色胺(5，7-DHT)使标记神经元的棘波宽度略有增加，并抑制了标记神经元的瞬间外向整流，但仍可根据其反应模式识别神经元。即使在出生后早期，神经元也表现出其主要特征。这些数据，以及从多巴胺能黑质神经元获得的数据，表明脑干单胺能神经元在出生时功能已经相当成熟，尽管它们的完全成熟似乎还需要2周。关于体内移植的单胺能神经元的性质变化，目前还没有得到明确的结果，还需要进一步的研究。

An attempt was made to identify living monoaminergic neurons for electrophysiology in a brain slice preparation in the hope that the procedure would enable to study the sequence of events which might occur in the course of functional maturation of developing an transplanted monoaminergic neurons. Thin (80-100 mu thick) brain-stem slices obtained from young rats (5-25 days old) were treated with a serotonin analogue, 5, 7-dihydroxytryptamine (5, 7-DHT). Neurons accumulating the substance fluoresced under ultraviolet light. The localization of labelled cells in the raphe nuclei suggested that they were serotonerigc neurons. No cells were labelled in the dopamine neuron-containing substantia nigra. Intracellular recording also revealed that the responsed of labelled neurons conformed to those reported for serotonergic raphe neurons ; the spike potential of the neurons was slow in time course, showing a hump on its falling phase, and their membrane time constant was long. Application of 5, 7-DHT slightly broadened the spike width and depressed the transient outward rectification of the labelled neurons, but the neurons were still identifiable by their pattern of responses.The time course of maturation of sprotonergic raphe neurons was studied using the above-mentioned procedure. The neurons showed the main traits of their character even at the early postnatal periods. The data, along with those obtained from dopaminergic nigral neurons, suggested that brain-stem monoaminergic neurons were functionally fairly mature at birth, although further 2 weeks seemed to be necessary for their full matumration. Concerning the changes in property of monoaminergic neurons transplanted in vivo, definitive results have not yet been obtained and further studies are needed.