Background data on NOD/Shi-scid IL-2Rγnull mice (NOG mice).

To obtain background data of NOD/Shi-scid IL-2Rγnull (NOG) mice, severely immunedeficient mice, a total of 120 animals were examined at 7, 26 and 52 weeks-old (20 mice/sex/group). The survival rate at 52 weeks-old was 95% (19/20) in both sexes. Clinically, circling behavior in one direction along the cage wall was observed in males after 8 weeks and females after 47 weeks-old, and hunchback position was found in males after 32 weeks-old. Hematologically, lymphocyte count markedly decreased at all ages, while white blood cell count increased in several mice at 52 weeks-old. Blood chemistry results revealed high values of aspartate aminotransferase, lactate dehydrogenase and creatine phosphokinase in some females at 26 weeks-old, without any related histological change. Histologically, lymphoid hypoplasia characterized by severe lymphocyte depletion with poorly developed tissue architectures was observed. In addition, spongiotic change in the nerve tissue was observed in both sexes at 7 and 26 weeks-old, and intracytoplasmic materials known as tubular aggregates in the skeletal muscles were found in males terminated at 26 and 52 weeks-old and in females at 52 weeks-old. Malignant lymphoma was found in one female euthanized at 20 weeks-old. Further, small intestinal adenoma, hepatocellular adenoma, leukemia, cerebral lipomatous hamartoma, Harderian gland adenoma and uterine polyp were also observed, and their incidences were low except for that of uterine polyp. This study provided detailed background data on NOG mice up to 52 weeks-old and provided information on appropriate use of NOG mice in the various research fields.

[Behavioral characteristics of open-field activities in NOD mice].

The open-field test was carried out on NOD mice of both sexes between the ages of 40 to 300 days. The behavior of both sexes of mouse was observed for 3-minute periods with an interval of 20 days. The mean scores of ambulation and rearing increased at the ages of 40-80 days old, and both scores decreased more than 100 days old. The onset of overt diabetes (DM) in female mice were observed after 120 days old. After the onset of DM with great loss of body weight, the scores of ambulation and rearing were dramatically decreased. Other parameters, urination, defecation, and preening were not changed with age of both sexes. These data suggest that conspicuous weight loss with the expression of overt diabetes in NOD female mouse might correlate to decrease of the ambulation and rearing scores.