The role of dietary zinc in modifying the onset and severity of spontaneous diabetes in the BB Wistar rat.

The goal of this study was to determine whether zinc supplementation in the diet of diabetes-prone BB Wistar rats will delay or prevent the onset of overt diabetes. Male Wistar BB rats were fed diets containing either 1000 ppm (HZ), 50 ppm (NZ), or 1 ppm zinc (LZ) starting at 30 days of age. Non-diabetes-prone rats were fed NZ and designated as controls (NORM). Beginning at 60 days, the rats were checked for glycosuria and, if positive, were given an i.p. glucose tolerance test (IPGTT). All remaining animals underwent an IPGTT at 100 days and were sacrificed. At 90 days of age HZ rats had a lower incidence of diabetes (19%) than NZ (53%) or LZ (44%) animals (P < 0.015). By age 100 days, for the HZ group, there was a 60% reduction in the number of expected overt diabetic rats. HZ animals also had higher concentrations of both pancreatic and serum insulin and exhibited lower serum glucose and triglycerides. Immunohistochemistry of HZ rats was clearly different from NZ rats and showed evidence of nearly normal pancreatic endocrine activity. Data indicate that dietary treatment of diabetes-prone BB Wistar rats with zinc appears to be an effective approach for delaying or preventing the onset of diabetes in genetically predisposed rodents. This finding may suggest further experimental studies regarding dietary means for preservation of pancreatic function.

Effect of insulin-like growth factor I in murine muscular dystrophy.

In muscular dystrophy there is an imbalance between muscle protein synthesis and protein degradation, resulting in net muscle catabolism and progressive muscle weakness and wasting. Both insulin and insulin-like growth factor I (IGF-I) are known to have an anabolic effect on skeletal muscle, which is believed to be enhanced in the presence of elevated concentrations of amino acids. We examined the effects of 4-week administration of recombinant human IGF-I (rhIGF-I), both alone and supplemented with a high protein diet (HPD), on muscle metabolism, morphology, and function in the 129 ReJ dystrophic mouse. rhIGF-I significantly reduced muscle protein degradation (P < 0.001), increased muscle protein content (P < 0.05), decreased fiber area variability (P < 0.01), and increased hind limb utilization (P < 0.01). Supplementation of rhIGF-I therapy with a HPD resulted in a significant increase in muscle protein synthesis (P < 0.05) in addition to a further increase in the above parameters. We conclude that rhIGF-I causes an improvement in muscle metabolism, morphology, and function in dystrophic mice, and this effect is further enhanced by the presence of a HPD.

Oral hydration solutions in experimental osmotic diarrhea: enhancement by alanine and other amino acids and oligopeptides.

Improvement of sodium absorption during the administration of oral hydration solutions (OHS) could increase the efficacy of formulations used in the treatment of infantile diarrhea. To test this hypothesis, selected protein breakdown products were evaluated as absorption enhancers in OHS of different osmolalities and Na-to-glucose ratios in an animal model of osmotic diarrhea induced by cathartics. A very significant increase in water and Na absorption occurred in rats with diarrhea when they were perfused with a 90-mmol/L-Na, 111-mmol/L-glucose OHS containing 30 mmol/L of L-alanine (Ala). The same effect on Na retention was observed with a protein hydrolysate (PrH) in rats with diarrhea. Glycine was not effective. Other experimental OHS were ineffective in rats with diarrhea. The data indicate that in this animal model of chronic diarrhea Na transport enhancers, such as Ala and a PrH, are most efficacious in the presence of higher Na concentration.