SPERMATOGENIC AND MUTAGENIC DAMAGE AFTER PATERNAL EXPOSURE TO SYSTEMIC INDIUM-114M

The cytotoxic and mutagenic consequences of systemic administration of In-114m have been examined. Adult male rats were dosed intraperitonea lly with 14.8 or 3.7 MBq/kg In-114m. Approximately 0.25% of the inject ed radioactivity was localized within the testis by 24 h and was retai ned with an effective half-life of 49.5 days. Breeding studies were st arted 3 days after injection, males being housed with two females for seven consecutive mating trials of 19 days, separated by 2 days. Indiu m-114m caused a reduction in litter size and an increase in the incide nce of pre- and postimplantation losses and dominant lethal mutations. These effects became evident from 24 days but were most marked betwee n 87-126 days after treatment and persisted up to 147 days. When anima ls were mated 200 days after treatment, no significant changes were ob served. In a parallel study, administration of 14.8 MBq/kg In-114m res ulted in decreased testis and epididymal weight and sperm reserves. Ma ximal reduction occurred between 87-108 days after injection followed by recovery toward control values, but neither organ had reached norma l levels at 200 days. A single dose of 3.7 MBq/kg, however, had no eff ect on reproductive organ weight or sperm content. Male F-1 progeny fr om the 14.8 MBq/kg group of the second mating period (commencing at 24 days) displayed decreased testis weights and sperm content and provok ed a higher incidence of dominant lethal mutations. This effect was no t observed in male progeny from any other time or the alternative dose level.