Singh A K, Banister E W
Can J Physiol Pharmacol. 1978 Apr;56(2):331-3. doi: 10.1139/y78-050.
The effect of 6-hydroxydopamine (6-OHDA) upon brain and blood catecholamines, ammonia, and amino acids has been studied in rats subjected to increasing doses of the drug. Time dependent effects after injection have also been studied. Systemically injected 6-OHDA significantly, acutely reduced brain adrenaline (A), noradrenaline (NA), total catecholamines (TC), gamma-aminobutyric acid (GABA), and glutamic acid (Glu); concomitantly brain ammonia (NH3) increased. In blood, NA and TC were reduced and A and NH3 increased. The changes in brain monoamines are surprising since it has been reported that 6-OHDA does not cross the blood-brain barrier. We have proposed that these changes result from a general stress response or a reflex peripheral sympathetic response to falling blood pressure which in some manner communicates to the central nervous system. As the dose of 6-OHDA increased, brain NH3 increased and Glu decreased. A similar effect was seen from a single dose as the time after injection for sampling brain and blood constituents increased. Blood ammonia increases without change in Glu, glutamine, or asparagine. The source of NH3 may be from deamination of adenine nucleotide or catechols released from nerve terminals under the abnormal stimulus of 6-OHDA.
在接受递增剂量6-羟基多巴胺（6-OHDA）的大鼠中，研究了6-OHDA对脑和血儿茶酚胺、氨及氨基酸的影响。还研究了注射后随时间变化的效应。全身注射6-OHDA可显著且急性地降低脑内肾上腺素（A）、去甲肾上腺素（NA）、总儿茶酚胺（TC）、γ-氨基丁酸（GABA）和谷氨酸（Glu）；同时脑内氨（NH3）增加。在血液中，NA和TC降低，A和NH3增加。脑单胺类的变化令人惊讶，因为据报道6-OHDA不能穿过血脑屏障。我们提出这些变化是由一般应激反应或对血压下降的反射性外周交感反应引起的，这种反应以某种方式传递到中枢神经系统。随着6-OHDA剂量增加，脑内NH3增加而Glu减少。从单次给药来看，随着注射后用于采集脑和血成分的时间增加，也会出现类似效应。血氨增加，而Glu、谷氨酰胺或天冬酰胺无变化。NH3的来源可能是在6-OHDA异常刺激下从神经末梢释放的腺嘌呤核苷酸或儿茶酚胺的脱氨基作用。
