Insulin resistance and sympathetic function in high spinal cord injury

Abstract

Objective: Cardiovascular disease (CVD) is today one of the main causes of death and aects spinal cord injured (SCI) earlier than able-bodied. Risk factors for CVD, such as decreased glucose tolerance, insulin resistance and increased fat mass, are all reported among SCI subjects and may be related to changes in sympathetic nervous system (SNS) function. Methods: In order to test our hypothesis of a relationship between metabolic disturbances and alterations in SNS function, glucose and adipose tissue metabolism was investigated by the hyperinsulinaemic normoglycaemic clamp and microdialysis. Body composition was determined by DEXA-scanning. The SNS function was evaluated in total body as well as above and below lesion level by radiolabelled noradrenaline (NA) isotope dilution technique. A 24 h continuous plasma-NA monitoring was performed in seven SCI subjects. Results: Following an oral glucose load the SCI group demonstrated normal glucose tolerance but impaired insulin sensitivity with a maximum insulin value of 83 mU.1 71 in SCI compared to 50 in siblings, while adipose tissue metabolism was normal compared to siblings. Fat tissue mass constituted 34% of body mass in SCI group compared to 21% in weightmatched controls. Peripheral aerent activation resulted in increased blood pressure, decreased heart rate and reduction in muscle and skin blood¯ow. Furthermore, lipolysis below lesion level was activated by peripheral stimulation (89 ± 135 mmol.l 71 ). The 24 h continuous monitoring revealed p-NA levels 41.40 nmol.l 71 sucient to induce lipolysis in 20% of the registrations. NA spillover below lesion level increased substantially following peripheral aerent stimulation (0.06 ± 0.90 pmol.min.71 .100 g 71 ), whereas spillover above lesion level increased during central activation. Conclusions: We found signs of decreased insulin sensitivity and increased fat tissue mass. Peripheral activation of SNS was visualised in the SCI group by increased transmitter spillover as well as increased lipolysis and vasoconstriction. The diurnal registration of NA levels indicated frequent episodes of peripheral sympathetic activation in the group. This may compensate for the inability of central activation of SNS and may contribute to maintain lipolysis activity as well as to generate insulin resistance in the group

Long-term body-weight-supported treadmill training and subsequent follow-up in persons with chronic SCI: effects on functional walking ability and measures of subjective well-being

“…These benefits certainly should not be ignored, especially since Type II diabetes and cardiovascular disease are prevalent secondary complications in the SCI population. [28][29][30] In addition to the physiological benefits of BWSTT, this type of therapy carries with it a significant potential to improve subjective well-being. In the present study, significant increases emerged in overall life satisfaction as well as satisfaction with physical function.…”

The association between regional body composition and metabolic outcomes in athletes with spinal cord injury

“…21,22 Little research has investigated the effect of physical activity on glucose tolerance and insulin action in the SCI population. Electrical stimulation of the lower-body muscles in paraplegics has been shown to improve glucose uptake in the paralyzed muscle 23 as well as glucose tolerance 24 and insulin sensitivity.…”

A review of body mass index and waist circumference as markers of obesity and coronary heart disease risk in persons with chronic spinal cord injury

“…14,15,[35][36][37] Triglyceride levels are 6-60% higher in SCI, although not always significantly so. 15,[35][36][37][38] Total and low-density lipoprotein (LDL) cholesterols are either higher, similar, or lower, than in able-bodied subjects; 15,16,37,39,40 the relatively small number of subjects and differences in subject characteristics studied may account for these discrepancies. Impaired glucose tolerance, insulin resistance and diabetes occur more frequently in SCI versus able-bodied persons.…”

“…Impaired glucose tolerance, insulin resistance and diabetes occur more frequently in SCI versus able-bodied persons. 15,38,[41][42][43][44][45] Other potential CHD risk factors after SCI include decreased physical activity, psychosocial factors (depression, isolation), and elevated plasma homocysteine and C-reactive protein. 46 Increased fat mass has also been identified as an important risk factor in chronic SCI and weight management is recommended as a key CHD prevention strategy.…”