Tetrahydrobiopterin synthesis rate and turnover time in neuronal cultures from embryonic rat mesencephalon and hypothalamus.
Tetrahydrobiopterin synthesis rate and turnover time in neuronal cultures from embryonic rat mesencephalon and hypothalamus.
复制标题
胚胎大鼠中脑和下丘脑神经元培养物中四氢生物蝶呤的合成率和周转时间。
DOI：
10.1111/j.1471-4159.1990.tb08830.x
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发表时间：
1990
影响因子：
4.7
通讯作者：
Kapatos,G
中科院分区：
文献类型：
--
作者：
Kapatos,G
在胚胎大鼠中脑（MES）和下丘脑（HYP）的培养物中，通过跟踪N-乙酰血清素（NAS）或2，4-二氨基-6-羟基嘧啶（DAHP）阻断BH 4生物合成后BH 4水平的下降，估计了6-（R）-（L-溴-1 ′，2 ′-二羟基丙基）-2-氨基-4-羟基-5，6，7，8-四氢蝶啶（四氢生物蝶呤，BH 4）的合成速率和转换时间。用最大有效浓度的NAS（200μM）或DAHP（10 mM）孵育8 h后，两种培养系统的BH 4含量均降低了75%。描述BH 4代谢的参数是根据BH 4的稳态水平和通过BH 4指数下降的非线性回归分析确定的一级速率常数计算的。使用替代方法确认这些参数，该方法检查了终止BH 4合成抑制后BH 4的一级回收率。HYP培养物中BH 4的稳态水平（70.3 ± 9.4 pg/培养物）显著高于MES（46.5 ± 2.8 pg/培养物）。MES（0.153 ± 0.015/h）和HYP（0.159 ± 0.014/h）的BH 4损失的平均分数速率常数相等。HYP（11.29 ± 2.13 pg/培养物/h）的计算BH 4合成速率显著高于MES（7.11 ± 0.85 pg/培养物/h），这是由于BH 4的稳态浓度更高。MES（6.68 ± 0.67 h）和HYP（6.40 ± 0.62 h）的BH 4周转时间以及MES（4.63 ± 0.46 h）和HYP（4.44 ± 0.43 h）的半衰期无差异。因此，辅因子的周转足够快，其合成或降解的改变可以急剧改变单胺生物合成的速率。这些数据还表明，BH 4代谢可能在含多巴胺神经元的群体之间是不同的。
6‐(R)‐(L‐erythro‐1′,2′‐Dihydroxypropyl)‐2‐amino‐4‐hydroxy‐5,6,7,8‐tetrahydropteridine (tetrahydrobiopterin, BH4) synthesis rate and turnover time were estimated in cultures derived from the embryonic rat mesencephalon (MES) and hypothalamus (HYP) by following the decline in BH4 levels after blockade of BH4 biosynthesis byN‐acetylserotonin (NAS) or 2,4‐diamino‐6‐hydroxypyrimidine (DAHP). BH4 content of both culture systems decreased by 75% following an 8‐h incubation with maximally effective concentrations of NAS (200μM) or DAHP (10 mM). Parameters describing BH4 metabolism were calculated from steady‐state levels of BH4 and first‐order rate constants determined by a nonlinear regression analysis of the exponential BH4 decline. These parameters were confirmed using an alternative procedure that examined the first‐order rate of recovery of BH4 following termination of BH4 synthesis inhibition. Steady‐state levels of BH4 in HYP cultures (70.3 ± 9.4 pg/culture) were significantly greater than that for MES (46.5 ± 2.8 pg/culture). The average fractional rate constants of BH4 loss for MES (0.153 ± 0.015/h) and HYP (0.159 ± 0.014/h) were equivalent. The calculated rate of BH4 synthesis was significantly greater for HYP (11.29 ± 2.13 pg/culture/h) than for MES (7.11 ± 0.85 pg/culture/h), owing to the greater steady‐state concentration of BH4. BH4 turnover time for MES (6.68 ± 0.67 h) and HYP (6.40 ± 0.62 h) and half‐life for MES (4.63 ± 0.46 h) and HYP (4.44 ± 0.43 h) did not differ. The turnover of the cofactor is thus rapid enough that alterations in its synthesis or degradation could acutely modify the rate of monoamine biosynthesis. These data also indicate that BH4 metabolism may be different between populations of dopamine‐containing neurons.