Orosco M, Nicolaidis S
College de France, Paris.
Brain Res Bull. 1994;33(3):289-97. doi: 10.1016/0361-9230(94)90196-1.
Microdialysis from the ventromedian (VMH) and paraventricular (PVN) regions and simultaneous infusion of insulin alone (orexigenic) or with glucose (anorexigenic) was performed in the free-feeding rat. Intravenous insulin infusion (1 IU in 1 ml over 1 h) resulted in the expected glucoprivic feeding and a decrease in dopamine (DA) and serotonin (5-hydroxytryptamine [5-HT]) with an increase in their respective metabolites, dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindolacetic acid (5-HIAA). These data are quite different from those observed in spontaneous ad lib feeding: increase in DA, 5-HT and 5-HIAA and decrease in DOPAC. These last changes were not superimposed on insulin effects when insulin-induced meals occurred. When food was not available, insulin infusion induced the same changes except an increase in DA levels which could probably be ascribed to stress. When insulin was infused together with a sufficient amount of glucose to prevent hypoglycemia, we observed the usual anorexigenic effect. Although this treatment had an effect on induced-feeding opposite to that following insulin alone, the changes in hypothalamic monoamines were similar. The only consistent overall change is finally the rise in 5-HIAA found in both spontaneous and induced feeding conditions. These data suggest that monoaminergic changes in the VMH and PVN are not directly implicated in the control of feeding but they rather reflect metabolic events that accompany this behavior.
在自由进食的大鼠中，对腹内侧核（VMH）和室旁核（PVN）区域进行微透析，并单独（致食欲）或与葡萄糖一起（抑食欲）同时输注胰岛素。静脉输注胰岛素（1小时内1毫升中含1国际单位）导致预期的糖缺乏性进食，多巴胺（DA）和5-羟色胺（5-羟色胺[5-HT]）减少，其各自的代谢产物二羟基苯乙酸（DOPAC）和5-羟吲哚乙酸（5-HIAA）增加。这些数据与在自发随意进食中观察到的数据有很大不同：DA、5-HT和5-HIAA增加，DOPAC减少。当发生胰岛素诱导的进食时，这些最后的变化并未叠加在胰岛素的作用上。当没有食物时，胰岛素输注除了可能归因于应激的DA水平增加外，诱导了相同的变化。当胰岛素与足够量的葡萄糖一起输注以防止低血糖时，我们观察到了通常的抑食欲作用。尽管这种处理对诱导进食的作用与单独输注胰岛素后的作用相反，但下丘脑单胺类物质的变化是相似的。最终唯一一致的总体变化是在自发和诱导进食条件下均发现5-HIAA升高。这些数据表明，VMH和PVN中的单胺能变化并非直接参与进食的控制，而是反映了伴随这种行为的代谢事件。
