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IMMUNOTOXICITY OF TRIBUTYLTIN OXIDE IN RATS EXPOSED AS ADULTS OR PRE-WEANLINGS
Citation:
Smialowicz, R. AND e. al. IMMUNOTOXICITY OF TRIBUTYLTIN OXIDE IN RATS EXPOSED AS ADULTS OR PRE-WEANLINGS. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/J-89/214 (NTIS PB90146168).
Description:
A comparison was made between adult and pre-weanling rats of the immunotoxic effects of acute dosing with bis(tri-n-butyltin) oxide (TBT0). dult (9 week old) male Fischer rats were dosed by oral gavage with TBT0 for 10 consecutive days at 2.5 to 10 mg/kg/dose or three times per week for a total of ten doses at 1.25 to 20 mg/kg/dose. Adult rats similarly dosed by oral gavage with 6 mg/kg/dose cyclophosphamide (CY) served as positive controls. Pre-weanling rats (3-24 days old) were dosed three times per week for a total of ten doses at 2.5, 5 or 10 mg/kg/dose. t various times after dosing, rats were evaluated for alterations in body and lymphoid organ weights, mitogen and mixed lymphocyte reaction (MLR), lymohoproliferative (LP) responses natural killer (NK) cell activity, cytotoxic T lymphocyte (CTL) responses and primary antibody plaque forming cell (PFC) responses. n adult rats given ten daily doses of TBT0, thymic involution was observed at a dosage of 2.5 mg/kg and mitogen responses to Con A and PHA were suppressed at 5 mg/kg. he PFC response was enhanced in adult rats dosed daily at 2.5 mg/kg. osage of 5 mg/kg given intermittently (three times a week) to adults or pre-weanlings resulted in thymic involution. eductions in mitogen responses were observed in adults dosed intermittently at 10 and 20 mg/kg and in pre-weanlings at 5 and 10 mg/kg. he MLR response was suppressed in adult rats dosed inter-mittently at 20 mg/kg and in preweanling rats at 10 mg/kg. K cell activity was suppressed only in pups dosed intermittently at 10 mg/kg. TL responses were not affected in either age group. Within three weeks following the last exposure of adult rats to TBT0 all parameters returned to normal. owever, LP responses to mitogens were suppressed in ten week old rats that were dosed with 10 mg/kg TBT0 as pre-weanlings. hese data indicate that exposure of young rats to TBT0 resulted in immune alterations at doses lower than those required to suppress responses in adults and as such are similar to earlier observations from this lab on the enhanced immunotoxicity of the organotin compound dioctyltin dlchloride (D0TC) in pre-weanling rats.