Brichard S M, Ongemba L N, Kolanowski J, Henquin J C
Unité de Diabétologie et Nutrition, University of Louvain Faculty of Medicine, Brussels, Belgium.
J Endocrinol. 1991 Nov;131(2):185-91. doi: 10.1677/joe.0.1310185.
Vanadate has been shown to improve glucose homoeostasis in mildly glucose-intolerant and severely insulin-resistant fa/fa rats. The present study examined whether changes in insulin counter-regulatory hormones contribute to this beneficial effect of vanadate. Since oral administration of Na3VO4 caused a decrease in food intake and stopped the increase in body weight, vanadate-treated fa/fa rats were compared with both controls with food available ad libitum and pair-fed rats. Slightly lower plasma glucose levels were maintained in conjunction with markedly lower plasma insulin levels in vanadate-treated rats, and this effect was not simply due to the smaller body weight of the animals. Compared with control rats, treatment with vanadate affected neither basal plasma glucagon levels nor the increase in glucagon levels observed after insulin-induced hypoglycaemia or after i.v. injection of arginine. Compared with pair-fed rats, treatment with vanadate prevented the fall in basal plasma glucagon and its exaggerated rise in response to insulin that mere food restriction produced. Plasma corticosterone levels were high in fa/fa rats. Vanadate and pair-feeding similarly decreased basal plasma levels of corticosterone as well as nocturnal corticosteronuria. Thus the attenuation of the hypercorticism of fa/fa rats results from the reduction in body weight gain rather than from a specific action of vanadate. Vanadate did not influence urinary excretion of noradrenaline, an index of neural sympathetic activity, but prevented the increase in adrenaline excretion, an index of adrenal medulla activity, that was produced by food restriction in pair-fed rats. In conclusion, vanadate administration has no or little specific effects on three major insulin counter-regulatory hormones. This reinforces the suggestion that the beneficial effects of vanadate on glucose homoeostasis in fa/fa rats are mainly due to a correction of insulin resistance in peripheral tissues.
钒酸盐已被证明可改善轻度葡萄糖不耐受和严重胰岛素抵抗的fa/fa大鼠的葡萄糖稳态。本研究探讨了胰岛素对抗调节激素的变化是否促成了钒酸盐的这种有益作用。由于口服Na3VO4会导致食物摄入量减少并阻止体重增加，因此将钒酸盐处理的fa/fa大鼠与自由进食的对照组大鼠和配对喂养的大鼠进行了比较。钒酸盐处理的大鼠血浆葡萄糖水平略低，同时血浆胰岛素水平显著降低，而这种作用并非仅仅是由于动物体重较小。与对照大鼠相比，钒酸盐处理既不影响基础血浆胰高血糖素水平，也不影响胰岛素诱导的低血糖或静脉注射精氨酸后观察到的胰高血糖素水平升高。与配对喂养的大鼠相比，钒酸盐处理可防止基础血浆胰高血糖素的下降及其因单纯食物限制而对胰岛素产生的过度升高反应。fa/fa大鼠的血浆皮质酮水平较高。钒酸盐和配对喂养同样降低了基础血浆皮质酮水平以及夜间皮质酮尿。因此，fa/fa大鼠高皮质醇血症的减轻是由于体重增加的减少，而非钒酸盐的特定作用。钒酸盐不影响去甲肾上腺素（神经交感活动指标）的尿排泄，但可防止配对喂养大鼠因食物限制而产生的肾上腺素排泄增加（肾上腺髓质活动指标）。总之，给予钒酸盐对三种主要的胰岛素对抗调节激素没有或几乎没有特定影响。这进一步支持了这样的观点，即钒酸盐对fa/fa大鼠葡萄糖稳态的有益作用主要是由于外周组织胰岛素抵抗的纠正。
