The potential developmental neurotoxicity of calcium cyclamate in CD rats

The developmental neurotoxicity of calcium cyclamate was evaluated in Sprague Dawley [Crl:CD(SD)] rats, administered in drinking water, in comparison to a concurrent control group (water) and a positive control group given propylthiouracil (PTU). Calcium cyclamate was administered to F0 females for 4 weeks prior to pairing, throughout mating, gestation and lactation and to F1 offspring from weaning to 12 weeks of age, PTU was administered by gavage to F0 females from Day 6 of gestation up to Day 20 of lactation. Target calcium cyclamate doses were 0, 250, 500 and 1,000 mg/kg bw/day, while the PTU dose was 0.5 mg/kg bw/day. No treatment-related effects of cyclamate were observed in either the F0 or F1 generations on reproductive performance or neurobehavioral development. In comparison, PTU exposure resulted in developmental delays, memory impairment and a number of neuropathological and morphometric outcomes. The results from the unique developmental neurotoxicity study design, corroborate the absence of hyperactivity and any other neurotoxic effects following cyclamate administration at levels up to 878 mg/kg bw/day in F0 females and 784 mg/kg bw/day in F1 animals. This demonstrates the suitability of PTU as a positive control and confirms the safe use of cyclamate as a no-calorie sweetener.