A collaborative dominant lethal study of triethylenemelamine in the rat

Abstract

A collaborative dominant lethal study of the known mutagen triethylenemelamine (TEM) was conducted in male rats. Six laboratories were supplied with animals from a common source and with TEM of the same lot number in an attempt to ensure uniformity of strain and drug effect. Male Sprague-Dawley rats, which were proven breeders, were divided into five groups of 15 animals each and were given a single ip injection of TEM at 0 (saline), 0.125, 0.250, 0.375, or 0.500 mg/kg. respectively. After the injection, each male was housed with two virgin females (200 g) each week for a 10-week period. The females were sacrificed by asphyxiation 14 days after the midweek of cohousing, and corpora lutea were counted and the uterine contents were examined. The results showed a highly significant difference among laboratories for the number of corpora lutea per pregnant female and for preimplantation losses over all doses and weeks. Variability among laboratories was least for total implants in both treated and control groups and dead implants in the control group. Although the variation was great between laboratories with respect to the several parameters considered, the results obtained by each laboratory did show that TEM has a significant mutagenic effect in the dominent lethal test.