Hemminga M A, Maaskant J J, van der Plas J, Gabbott P A
Gen Comp Endocrinol. 1985 Aug;59(2):301-7. doi: 10.1016/0016-6480(85)90382-x.
In the freshwater pulmonate snail Lymnaea stagnalis glycogen synthesis in the glycogen storage cells (GC) is stimulated by increasing external glucose concentrations. On the other hand, a hyperglycemic factor from the CNS inhibits glycogen synthesis and stimulates glycogen breakdown in these cells. This CNS factor may be involved in the physiological control of glycogen mobilization. In the present study the interaction between the inhibiting effect of the CNS factor and the stimulating effect of increasing glucose concentrations on glycogen synthesis in isolated GC was investigated. The results, analyzed by determination of the Michaelis-Menten parameters for saturation kinetics, suggest that the CNS factor increases the glucose concentration required for half-maximal stimulation of glycogen synthesis, but does not influence the maximum rate of synthesis (competitive type of inhibition). The role of the hyperglycemic factor during conditions of glycogen breakdown was investigated by extirpation of the cerebral ganglia (-CG), which contain the main release sites of the factor. Extirpation did not affect the hemolymph glucose concentration or the glycogen levels in the GC during starvation. However, -CG animals showed reduced levels of the hyperglycemia normally associated with exposure to anaerobic conditions.
在淡水肺螺类蜗牛椎实螺中，糖原储存细胞（GC）中的糖原合成会受到外部葡萄糖浓度升高的刺激。另一方面，来自中枢神经系统的高血糖因子会抑制这些细胞中的糖原合成并刺激糖原分解。这种中枢神经系统因子可能参与糖原动员的生理控制。在本研究中，研究了中枢神经系统因子的抑制作用与葡萄糖浓度升高对分离的GC中糖原合成的刺激作用之间的相互作用。通过测定饱和动力学的米氏参数进行分析的结果表明，中枢神经系统因子会增加糖原合成半最大刺激所需的葡萄糖浓度，但不影响最大合成速率（竞争性抑制类型）。通过切除含有该因子主要释放部位的脑神经节（-CG），研究了高血糖因子在糖原分解条件下的作用。切除在饥饿期间不影响血淋巴葡萄糖浓度或GC中的糖原水平。然而，-CG动物显示出通常与暴露于无氧条件相关的高血糖水平降低。
