Immune response of adult rats is altered by administration of diazepam in the first postnatal week

The potential innnunotoxic risk of perinatal treatment with diazepam was investigated using early postnatal administration of the drug to the rat and monitoring the immune response until the age of 24 months. Rats given a single dose of diazepam 10 mg/kg SC on the seventh postnatal day revealed at the age of 6 months a depression of cell-mediated immune response, and at the age of 12 months significant decrease of humoral immune response. The latter persisted until senescence (age 24 months). Also, a repeated dosage of diazepam (3 x 5 mg/kg/day SC on postnatal days 5 to 7) induced a significant depression of humoral immune response in 7-month-old rats. The results demonstrate that both the humoral and cell-mediated immune response of adult rats can be altered by administering diazepam in early postnatal life.