Abstract
Age-associated bone changes in the Senescence-Accelerated Mouse (SAM)-P/6/Ta and its control, SAM-/1/Ta reared under specific pathogen-free (SPF) conditions were examined. Morpometric analysis of the femurs in 3- and 5-month-old SAM-P/6/Ta revealed obvious reduction of bone volume as evidenced by a decreased cortical area and an increased marrow area in the mid-shaft compared with those in SAM-R/1/Ta of the same ages. Chemical analysis of the femurs showed a decrease in hydroxyproline content in SAM-P/6/Ta at 3 and 5 months of age. The femoral calcium content was varied with age. The body weight of SAM-P/6/Ta tended to be increased at 5 months and was significantly increased at 7 months; thus increase in body weight was associated with a significant increase in the weight of the epididymal fat pads. The serum insulin level in 5-month-old SAM-P/6/Ta exhibited a tendency to be increased over that of the control. Oral glucose tolerance test conducted at 7 months of age demonstrated a decreased glucose tolerance in the SAM-P/6/Ta.
These results indicate that SPF SAM-P/6/Ta develops the same bone reduction previously reported to occur in conventionally-reared SAM-P/6. However, SPF SAM-P/6/Ta is concluded to be a murine model that is characterized by bone loss, obesity, possible hyperinsulinemia, and glucose intolerance.
