Protection by thymosin fraction 5 from streptozotocin-induced diabetes in mice

Protection by thymosin fraction 5 (TF5) from subdiabetogenic-dose streptozotocin (STZ)-induced type I diabetes in CD-1 mice was investigated. Mice which received multiple subdiabetogenic-dose (35 mg/kg) injections of STZ became hyperglycemia within two weeks. Hyperglycemia was also induced in those treated with low dose of TF5 (0.01 mg/day) in addition to STZ, though it was somewhat mild. In contrast, animals given STZ plus high dose of TF5 (0.1 mg/day) remained normoglycemic throughout the whole observation period (within 4 weeks). In the pancreatic islets from these animals, histologically, the well-granulated beta cells were observed and the infiltration of lymphoid cells was absent or mild. These results suggest that the administration of TF5 prevents the induction of insulitis and hyperglycemia in the subdiabetogenic-dose STZ-treated mice.