IN-VIVO EFFECTS OF GLUCOSE AND INSULIN ON SECRETION AND GENE-EXPRESSION OF GLUCAGON IN RATS

被引:15
作者
MAGNAN, C [1 ]
PHILIPPE, J [1 ]
KASSIS, N [1 ]
LAURY, MC [1 ]
PENICAUD, L [1 ]
GILBERT, M [1 ]
KTORZA, A [1 ]
机构
[1] CTR MED UNIV GENEVA, DEPT MICROBIOL & MED, GENEVA, SWITZERLAND
关键词
D O I
10.1210/en.136.12.5370
中图分类号
R5 [内科学];
学科分类号
1002 ; 100201 ;
摘要
We investigated the effects of insulin and glucose on the control of secretion and gene expression of glucagon in vivo in rats. Animals were studied during 1) a 48-h period of either glucose infusion (hyperglycemia plus hyperinsulinemia; HG-HI rats) or insulin infusion (euglycemia plus hyperinsulinemia; EG-HI rats), and 2) a prolonged postinfusion period in both groups. In HG-HI rats, elevation of plasma insulin and glucose concentrations by about 7 and 5 times, respectively, resulted in a decline in glucagon levels, which fell significantly within 6 h and remained low thereafter, whereas these levels were unchanged in EG-HI rats. Glucagon messenger RNA levels and pancreatic glucagon content were not significantly affected in either HG-HI or EG-HI rats. After cessation of infusions, hypoglycemia occurred in both group of rats. In HG-HI rats, hypoglycemia lasted for about 36 h without any surge in the plasma glucagon level, whereas in EG-HI rats it was transient (similar to 1 h) and stimulated glucagon secretion. In both groups the pancreatic or-cell was unresponsive to arginine during the postinfusion period. In conclusion, although a role of intraislet insulin cannot be excluded, glucagon gene expression is insensitive to changes in plasma glucose and insulin concentrations. In contrast, hyperglycemia/hyperinsulinemia, not hyperinsulinemia alone, lowers glucagon secretion and affects the a-cell responsiveness to hypoglycemia.
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页码:5370 / 5376
页数:7
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