Functional Correlations Between Hypothalamus and Hepatic Metabolism

在大鼠肝脏原位无再循环灌流模型上，研究了肝交感神经在糖原分解中的作用。在肝门周围放置双极铂电极，施加矩形单相脉冲(20V，2ms，20 Hz)。在雌性大鼠肝脏中，苯肾上腺素和异丙肾上腺素均能刺激糖原分解，而神经刺激(NS)的作用可被酚妥拉明完全阻断。磷脂酶A_2抑制剂美帕克林可显著抑制NS引起的糖原分解，但不影响去甲肾上腺素的溢出。然而，它对苯肾上腺素的糖原分解没有影响。前列腺素F_2可模拟NS的作用，而酚妥拉明对PGF_2无影响。这些结果表明，在大鼠肝脏中，通过α受体介导的功能产生的二十烷类化合物在NS激活糖原分解过程中起重要作用。有报道称酵母多糖(酵母细胞壁颗粒)被库普弗细胞选择性地摄取，而且酵母多糖能够刺激二十烷类化合物的产生。本实验研究了交感神经刺激和酵母多糖对冷暴露大鼠肝脏灌流后糖原分解的直接影响。结果提示，冷暴露时肝神经可能参与调节枯否细胞的花生四烯酸通路。

The actions of hepatic sympathetic nerves on glycogenolysis were studied in rat livers perfused in situ without recirculation. A bipolar platinum electrode was placed around the hepatic hilus and rectanglar monophasic impulses (20V, 2ms, 20Hz) were applied. In female rat livers both phenylephrine and isoproterenol stimulated glycogenolysis, but the effects of nerve stimulation (NS) were completely abolished by phentolamine. Mepacrine, a phospholipase A_2 inhibitor, markedly suppressed glycogenolysis by NS without affecting norepinephrine overflow. It had no effect, however, on glycogenolysis by phenylephrine. Prostaglandin F_<2alpha> (PGF_<2alpha>) mimicked the effect of NS but phentolamine had no effect on PGF_2. These results suggest that in rat livers eicosanoids produced via an alpha-receptor mediated function play a vital role in the activation of glycogenolysis by NS. Since it has been reported that zymosan (Cell wall particles from yeast) is selectively taken up by kupffer cells and that zymosan is able to stimulate production of eicosanoids, the experiments were carried out to examine the direct effects of sympathetic nerve stimulation and zymosan on glycogenolysis in perfused liver isolated from rats exposed to cold. The results suggest that hepatic nerve may regulate the arachidonic pathways in kupffer cells during cold exposure.