An age-dependent alteration of the respiratory exchange ratio in the db/db mouse / 한국실험동물학회지

The leptin receptor-deficient db/db mouse is a rodent model of type 2 diabetes and obesity. Diabetes in db/db mice shows an age-dependent progression, with early insulin resistance followed by an insulin secretory defect resulting in profound hyperglycemia. However, there is insufficient data on agedependent changes of energy metabolism in db/db mice. We demonstrated an age-dependent decrease in the respiratory exchange ratio (RER), calculated by a ratio of VO2/VCO2, in db/db mice. The RER determined by indirect calorimetry, was 1.03 in db/db mice under 6 weeks of age, which were similar to those in heterozygote (db/+) and wild-type (+/+) mice. However, RER decreased from approximately 0.9 to 0.8 by 10 weeks of age and subsequently returned to approximately 0.9 at 22 weeks of age. The changes in RER were concurrent with the alterations in body weight and blood glucose level. However, other metabolic indicators such as glucose tolerance, changes in body fat mass, and urinary glucose levels, did not change with age. The results suggested that the energy source utilized in db/db mice changed with the age-related progression of diabetes.

Age-related prevalence of antibodies to infective-larvae of Wuchereria bancrofit in normal individuals from a filaria-endemic region.

Antibody isotypic levels (IgM, IgE and IgG subclasses) to infective larvae (L3) of Wuchereria bancrofti were measured in 104 normal individuals from a filaria-endemic region in Orissa. The titres of antibodies were considerably higher in adults (n = 25, 25·1 ± 3·8 year) than in children (n = 52, 7·1 ± 2·1 year). Young children (n = 14) less than four years were seronegative to all isotypes other than IgM, the sero-conversion to which was achieved in the children (n=15) by the age of 7·5±1·2 years. The prevalence of other isotypes increased with age and reached a maximum in early adulthood (18·6 ± 1·6 years), which persisted in older adults (> 30 years). However, the increase in IgG3 prevalence with age was less marked. IgG2 was detected only after 10 years of age. Compared to the high prevalence (100%) of IgM, IgE, IgG1, and IgG2, in adults. IgG3 and IgG4 prevalences were low, 35% and 28% respectively. IgA level to L3 antigen was found to be extremely low even in adults. These data indicate that the prevalence of L3 antibodies was different for different isotypes and the acquisition of antibody response essentially followed an age dependent pattern.