Rindi G, Comincioli V, Reggiani C, Patrini C
Brain Res. 1984 Feb 20;293(2):329-42. doi: 10.1016/0006-8993(84)91240-x.
Different steps of the metabolism of thiamine (T), thiamine mono- (TMP), pyro- (TPP) and triphosphate (TTP) in the cerebellum, brainstem, cerebral cortex and the sciatic nerve were evaluated in the rat in vivo. The radioactivity of T and its phosphoesters was determined at fixed time intervals (0.5-240 h) after an intraperitoneal injection of [14C]T (30 micrograms:1.25 muCi), under steady state conditions. The dynamics of thiamine compounds was evaluated using a compartmental mathematical model that allowed the fractional rate constants (FRC), turnover rates (TR) and turnover times to be calculated. The phosphorylation of T to TPP and the dephosphorylations of TPP to TMP and TMP to T could be estimated in all the structures investigated. Their turnover rates were found to be ordered in the sequence: cerebellum greater than brainstem greater than cerebral cortex greater than sciatic nerve. The transphosphorylation of TPP to TTP was so small that it could not be determined in a reliable way. Regional differences were found both the rate and in the composition of T and TMP mixture released from nervous structures. The shortest turnover time of TPP was found in the cerebellum, while the sciatic nerve exhibited the fastest renewal of T and TMP. In all the structures investigated TPP had a rather short turnover time, suggesting that its function might be associated to a rapid conversion into chemically different forms. The possible relationships between the rates of turnover of T compounds are the sensitivity of the nervous structures to T deficiency are discussed.
在大鼠体内评估了硫胺素（T）、硫胺素单磷酸酯（TMP）、焦磷酸硫胺素（TPP）和三磷酸硫胺素（TTP）在小脑、脑干、大脑皮层和坐骨神经中的不同代谢步骤。在稳态条件下，腹腔注射[14C]T（30微克：1.25微居里）后，在固定时间间隔（0.5 - 240小时）测定T及其磷酸酯的放射性。使用房室数学模型评估硫胺素化合物的动力学，该模型可计算分数速率常数（FRC）、周转率（TR）和周转时间。在所研究的所有结构中，均可估计T磷酸化为TPP以及TPP去磷酸化为TMP和TMP去磷酸化为T的过程。发现它们的周转率顺序为：小脑＞脑干＞大脑皮层＞坐骨神经。TPP向TTP的转磷酸化作用非常小，无法可靠测定。在神经结构释放的T和TMP混合物的速率和组成方面均发现了区域差异。TPP的周转时间在小脑中最短，而坐骨神经中T和TMP的更新最快。在所研究的所有结构中，TPP的周转时间都相当短，这表明其功能可能与快速转化为化学上不同的形式有关。讨论了T化合物周转率与神经结构对T缺乏敏感性之间的可能关系。
