Hematologic and biochemical changes associated with age and strain in aged B6 mice breeding in the National Center of Geriatrics and Gerontology

At the National Center of Geriatric and Gerontology (NCGG), aged mice and rats are used in research on aging and the treatment and prevention of gerontological diseases. Some of the most commonly used mouse strains in our center and general research were the C57BL/6J (B6J) and C57BL/6N (B6N). In this study, hematological and biochemical changes related to age, strain, and sex, from 3 months (mo) to 24 mo, were characterized every 3 mo in the B6J and B6N strains. Hematological results showed that in B6J males at 24 mo, the levels of WBC, especially lymphocytes, were higher than in the B6N strain. In males B6J, the number of CD4+ T cells did not decrease significantly between 6 and 24 mo, but in females and strain B6N, the number of CD4+ T cells decreased significantly. The levels of red blood cells (RBC) and hemoglobin (HGB) were reduced with age in all strains, while the number of platelets (PLT) increased. Biochemical parameters, Blood urea nitrogen (BUN) and Creatinine (CRE) in B6J males were significantly higher than in the other groups at 24 mo. Glutamate oxalacetate transaminase/aspartate aminotransferase (GOT/AST) and glutamate pyruvate transaminase/alanine aminotransferase (GPT/ALT) levels were higher in the B6N strain than the B6J strain at 24 mo. The present results revealed significant variations in hematological and biochemical parameters between the two strains and between sexes as a result of genetic and hormonal differences in laboratory mice.