Abstract
Development of infectious disease or tumor diseases has been suggested to be easy in the older animals due to an immunodeficiency following with age. Although insulin has the activated effects to T cell, insulin secretion or sensitivity decrease in older animals, therefore it is possible that effect of the insulin stimulation to T cells activation decline by aging. This study was undertaken to examine whether peripheral leukocyte reaction is regulated by the mitogen stimulation with insulin following aging in dogs. Forty fore of healthy beagle dogs were used in this study, and the animals were divided three groups, Group 1（1 to 3 years old）, Group 2（4 to 7 years old）and Group 3（over 8years old）. Heparinezed blood was collected these dogs, and analyzed lymphocyte proliferation and expression of IFN-γ and IL-4 mRNA of mononuclear cells by concanavalin A（ConA）stimulation with or without insulin in vitro. The lymphocyte proliferation in Group 3 stimulated by ConA with insulin was lower than that in Group 1 and Group 2, and there was a significant difference between Group 2 and Group 3. The levels of IL-4 mRNA in three groups were higher by ConA stimulation with insulin compared to only ConA. The level of IL-4 mRNA stimulated by ConA with insulin in Group 3 was significantly higher than that in Group 1. These finding was suggest that the difference of insulin stimulation to T cells between older dogs and younger one may affect to immune disorder following aging.
