Slenzka K, Appel R, Rahmann H
University of Stuttgart-Hohenheim, Institute of Zoology, Germany.
Neurochem Int. 1995 Jun;26(6):579-85. doi: 10.1016/0197-0186(94)00176-u.
Glucose-6-phosphate dehydrogenase activity was studied in the brain of the cichlid fish Oreochromis mossambicus during early ontogenetic development. In general a slight but continuous decrease in enzyme activity was found (9.5 +/- 0.5 nmol substrate cleaved per mg protein and per min at developmental stage 13 [= 1 day post hatch at 28 degrees C] to a value of 7.9 +/- 0.6 in adult brain). In order to investigate the possible influence of altered gravity during early ontogenetic brain development, fish larvae were exposed to an increased acceleration of three times earth gravity (3 g) or to functional weightlessness in a fast-rotating clinostat for 7 days. A significant increase of brain G6PDH activity of approx. 15% was found after exposure to hyper gravity, whereas a significant decrease of the enzyme activity, approximately 10%, was detected following functional weightlessness in respect to the corresponding 1 g controls. Analyses concerning the regain of normal control enzyme activity of the larvae revealed dramatic fluctuations within the first 5 h after exposure to an increased acceleration of 3 g. Thereafter, between day 1 and day 3 after exposure, brain glucose-6-phosphate dehydrogenase decreased slowly. At day 3 after exposure no further differences of the hyper-g larvae compared to the controls were found. Only slight changes in total brain glucose-6-phosphate dehydrogenase activity occur during ontogenetic development of cichlid fish. This suggests that a more or less constant enzyme activity is important during brain development, but is reacting very sensitively to changes in the environmental factor gravity.
在莫桑比克罗非鱼早期个体发育过程中，对其大脑中的葡萄糖-6-磷酸脱氢酶活性进行了研究。总体而言，发现酶活性有轻微但持续的下降（在发育阶段13[=28℃孵化后1天]时，每毫克蛋白质每分钟裂解9.5±0.5 nmol底物，到成年大脑时降至7.9±0.6）。为了研究早期个体发育大脑发育过程中重力改变的可能影响，将鱼幼虫暴露于三倍地球重力（3g）的增加加速度下，或在快速旋转的回转器中暴露于功能失重状态下7天。暴露于超重环境后，大脑G6PDH活性显著增加约15%，而在功能失重后，相对于相应的1g对照组，酶活性显著下降约10%。对幼虫正常对照酶活性恢复的分析显示，在暴露于3g增加加速度后的前5小时内有剧烈波动。此后，在暴露后的第1天至第3天之间，大脑葡萄糖-6-磷酸脱氢酶缓慢下降。在暴露后第3天，与对照组相比，超重幼虫没有发现进一步的差异。在罗非鱼个体发育过程中，全脑葡萄糖-6-磷酸脱氢酶活性只有轻微变化。这表明，在大脑发育过程中，或多或少恒定的酶活性很重要，但对环境因素重力的变化反应非常敏感。
