Dorsal root ganglia from streptozotocin-diabetic rats and age- and weight-matched control animals were incubated with 4-amino 3H-butyric acid. A significant reduction in uptake was observed in the diabetic animals. The incorporation of 3H-leucine into protein was also significantly reduced but the results did not allow a conclusion as to whether this was a secondary or an independent effect. These findings are discussed in relation both to the abnormalities known to develop in diabetic rats and to the causation of human diabetic neuropathy.

Animals↗

PubMed1984

Insulin resistance in older rats.

Insulin-stimulated glucose utilization was estimated in vivo in 1.5-, 4-, and 12-mo-old rats with an insulin suppression test wherein the height of the steady-state plasma glucose ( SSPG ) concentration, at similar steady-state plasma insulin levels, provides a direct reflection of the efficiency of insulin-stimulated glucose disposal. In parallel studies, the effect of age on in vitro insulin-stimulated glucose uptake was assessed in perfused hindlimb preparations. In addition, changes in the activity of enzymes that regulate muscle glycolysis, glycogenesis, and glycogenolysis were determined in isolated soleus muscle. The results indicated that rats got heavier as they became older, and changes in weight were associated with parallel increases in mean (+/- SE) SSPG concentrations as rats grew from 1.5 (56 +/- 3 mg/dl) to 4 (172 +/- 6 mg/dl) to 12 mo of age (194 +/- 8 mg/dl). The age-related decline in in vivo insulin action was associated with a reduction in insulin action on muscle, and maximal insulin-stimulated glucose uptake by perfused hindlimbs of 12-mo-old rats was approximately 50% of the value seen with perfused hindlimbs from 1.5-mo-old rats. Soleus muscle enzyme activity also varied with age, with significant increases in glycogen synthase and decreases in glycogen phosphorylase documented. Furthermore, muscle glycogen phosphorylase activity, which fell during an insulin infusion in 1.5-mo-old rats, did not change when 12-mo-old rats were infused at comparable insulin levels. Finally, glycogen content was significantly increased (P less than 0.01) in soleus muscle from 12-mo-old rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗

PubMed1984

Field evaluation of a new simplified method for cooling of heat casualties in the desert.

Explore the source record for details and available documents.

Adult↗

PubMed1983

Sucrose-induced insulin resistance in the rat: modulation by exercise and diet.

Isocaloric substitution of sucrose for starch results in hyperinsulinemia and deterioration of glucose tolerance, suggesting a loss of insulin sensitivity. In this study we have quantitated the insulin resistance which develops with sucrose feeding, and evaluated the ability of dietary fiber, or an increase in skeletal muscle activity, to inhibit, or even prevent, the detrimental effect of sucrose feeding on in vivo insulin action. Thus, 6-wk-old rats were fed one of the following regimens for three weeks: a 64% cornstarch diet (C), a 32% cornstarch + 32% sucrose diet (S), the (S) diet containing added wheat bran fiber (S/F), and the (S) diet given to rats running spontaneously in exercise wheel cages (S/ET). Insulin sensitivity was evaluated by comparing steady-state plasma glucose (SSPG) concentrations at constant plasma insulin levels approximately 70 microU/ml attained during the continuous infusion of epinephrine (0.08 micrograms/kg/min), propranolol (1.7 micrograms/kg/min), glucose (8 mg/kg/min), and insulin (2.5 mU/kg/min) to each experimental group. The results show that rats fed the S diet had a significant increase (p less than 0.01) in mean (+/- SEM) SSPG concentration compared with rats fed the C diet (255 +/- 14 versus 165 +/- 3 mg/dl). SSPG concentrations, although lower (p less than 0.05) in rats fed S/F (205 +/- 8 mg/dl), were still higher (p less than 0.05) than the C levels (165 +/- 3 mg/dl). However, S/ET completely inhibited the increase in SSPG concentration seen in rats fed S and the values were actually lower (p less than 0.05) than in rats fed C (100 +/- 10 versus 165 +/- 3 mg/dl). In conclusion 1) sucrose feeding results in a loss of insulin sensitivity in normal rats; 2) addition of fiber attenuates, but does not completely prevent, the loss of insulin sensitivity associated with feeding sucrose; 3) exercise training prevents the loss of insulin sensitivity seen in sucrose-fed rats, and actually improves glucose uptake beyond that seen in the control group. These results document the profound effect of environmental factors on in vivo insulin action.

Animals↗

PubMed1981