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  • 1
    Electronic Resource
    Electronic Resource
    Increased mitogen-activated protein kinase expression and activity in white adipose tissue of ventromedial hypothalamus-lesioned rats (1997)
    Springer
    Diabetologia 40 (1997), S. 533-540 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Insulin signalling ; MAP-kinase ; insulin receptor ; insulin sensitivity ; obesity ; white adipose tissue.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Ventromedial hypothalamus lesions in rats induce hyperphagia and hyperinsulinaemia associated with a rapid growth of white adipose tissue resulting in massive obesity. It has been shown previously that at an early stage after the lesion, during the dynamic phase of obesity, the white adipose tissue is hyper-responsive to insulin. In the present work, we show that the effects of insulin on the autophosphorylation of the insulin receptor and on its tyrosine-kinase activity towards endogenous substrates are similar in intact adipocytes of control and ventromedial hypothalamus lesioned rats. One week after the lesion, the expression of phosphatidylinisitol 3-kinase and RAF-1 kinase, evaluated by Western-blotting, was similar in control and ventromedial hypothalamus lesioned rats. In contrast, an important increase in the expression of extracellular signal regulated kinase 1 protein was observed in white adipose tissue of ventromedial hypothalamus lesioned compared to control animals. No difference in the expression of extracellular signal regulated kinase 1 mRNA was observed in adipose tissue of control and ventromedial hypothalamus lesioned rats, suggesting that a post-transcriptional mechanism is involved in the over-expression of extracellular signal regulated kinase 1. The kinase activity of extracellular signal regulated kinase 1 and 2 is also markedly increased in adipocytes of ventromedial hypothalamus lesioned compared to control rats, both in the basal state and after insulin stimulation. Six weeks after the ventromedial hypothalamus lesion, this increase in mitogen-activated protein kinase expression and activity was still observed in adipocytes of ventromedial hypothalamus lesioned rats. These results suggest that an early and sustained increase in the expression and activity of mitogen-activated protein kinase may participate in the development of white adipose tissue in ventromedial hypothalamus lesioned rats. [Diabetologia (1997) 40: 533–540]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250050712
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Normal insulin sensitivity during the phase of glucose intolerance but insulin resistance at the onset of diabetes in the spontaneously diabetic BB rat (1989)
    Springer
    Diabetologia 32 (1989), S. 839-844 
    Details
    ISSN: 1432-0428
    Keywords: BB rat ; diabetes ; glucose intolerance ; insulin sensitivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In diabetes-prone BB rats, 30 to 50% of animals undergo autoimmune destruction of the pancreatic B-cells leading to a short period of glucose intolerance, followed by an abrupt onset of diabetes. We have examined whether the glucose intolerance period and the onset of diabetes are associated with changes in insulin sensitivity, using the euglycaemic hyperinsulinaemic clamp coupled with [3-3H] glucose infusion. Glucose intolerant rats were detected by a transient glycosuria one hour after an oral glucose load performed every four days. Insulin sensitivity studied in these rats the day following their detection was normal. Other diabetes-prone BB rats were tested daily and studied on the first day of glycosuria. In the basal state, glucose production was increased in diabetic rats (11.3±1.1 vs 7.1±0.8mg·min−1·kg−1, p〈0.05). Tissue glucose utilization was similar in diabetic and control rats (8.3±0.5 vs 7.1±0.8mg·min−1·kg−1) despite a three fold higher glycaemia in the diabetic rats. During the hyperinsulinaemic clamps, glycaemia was clamped at 6.1–6.6 mmol/l in diabetic and control rats. A decreased insulin sensitivity was observed in diabetic rats at submaximal (200 μU/ml) and maximal (1500 μU/ml) insulin concentrations for both inhibition of hepatic glucose production and stimulation of glucose utilization. No autoantibodies against insulin could be detected in the plasma of diabetic rats. Plasma concentrations of glucagon, catecholamines, ketone bodies and fatty acids were similar in control and diabetic rats during the clamp studies. Our results suggest that the decrease of basal insulin concentration is responsible for the insulin resistance in the diabetic BB rat at onset of diabetes, either directly or through the increased glycaemia.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00297448
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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