- 期刊
Metabolic Fate of Intravenously Administered N-Acetylneuraminic Acid-6-14C in Newborn Piglets
以靜脈注射放射性6-^14C标记的N-乙酰神经氨酸在新生猪里的代谢情形
摘要
唾液酸（Sialic Acid）（N-acetylneuraminic acid，N-乙酰神经氨酸）是神经节苷脂（ganglioside）和唾液酸糖蛋白（sialylglycoprotein）的组成成分之一。在生命初期，因为内源合成的唾液酸有限，唾液酸可能是一种重要的条件营养素。该研究的目的是调查经静脉注射、带放射性6－14C标记的N-乙酰神经氨酸（唾液酸）在新生猪里的代谢途径。方法：通过颈静脉注射5 μCi （11-12x106 cpm）的6－14C-N-乙酰神经氨酸（比活度为55 mCi/mmol）到三天大的雄性新生猪（Sus scrofa）里。在注射后的120分钟内定时抽取血样。120分钟后取出器官并且收集尿样来测定残留的放射性。结果：在注射后两分钟内，血样中的放射性的6－14C标记的N-乙酰神经氨酸减少了80%，而在120分钟后，血样中残余的放射性下降至接近8%。在注射后120分钟的时候，脑部里的放射性（cpm/g 组织）比肝脏、胰腺、心脏和脾里的放射性显著要高，但是却比肾脏里的要低。在脑部里，大脑含有注射的总放射性的百分比最高（0.175±0.0080），随之是小脑（0.0295±0.006, p= 0.00006）和丘脑（0.029±0.006, p= 0.00003）。结论：外源性游离唾液酸可以穿过血脑屏障（blood brain barrier）并且可以进入各种组织。这些发现表明从饮食中摄取的唾液酸可能有助于新生哺乳动物的早期脑部发育。
並列摘要
Background: Sialic acid (N-acetylneuraminic acid), a component of gangliosides and sialylglycoproteins, may be a conditional nutrient in early life because endogenous synthesis is limited. The aim of this study was to investigate the metabolic fate of intravenously administrated N-acetylneuraminic acid 6^14C (sialic acid) in piglets. Method: Three-day-old male domestic piglets (Sus scrofa) were injected via the jugular vein with 5 μCi (11-12x10^6 cpm) of N-acetylneuraminic acid-6^14C (specific activity of 55 mCi/mmol). Blood samples were collected at regular intervals over the next 120 min. The organs were then removed and the urine collected for determination of residual radioactivity. Results: Within 2 min of injection, 80% of the activity was removed from the blood and by 120 min the remaining activity approached 8%. At 120 min, the brain contained significantly more radioactivity (cpm/g tissue) than the liver, pancreas, heart and spleen, but less than the kidneys.Within the brain, the percentage of total injected activity was highest in the cerebrum (0.175 ± 0.008) followed by the cerebellum (0.0295 ± 0.006, p = 0.00006) and the thalamus (0.029 ± 0.006, p = 0.00003). Conclusions: An exogenous source of sialic acid is capable of crossing the blood-brain barrier and being taken up into various tissues. The findings suggest that dietary sources of sialic acid may contribute to early brain development in newborn mammals.