Testicular responses of rats and dogs to cyclohexylamine overdosage

Cyclohexylamine (CHA), the principal metabolite of cyclamate, was given by oral gavage to male rats (200 mg/kg/day) and male Beagles (250 mg/kg/day) for 9 wk. Subsequently some of these animals were maintained undosed for 13 wk to assess recovery. CHA adversely affected body-weight gain and food consumption in both species. Although a degree of tolerance developed, vomiting tended to occur after CHA administration to dogs. Serum follicle stimulating hormone levels increased and testosterone levels decreased in rats given CHA. No effects were found on the serum luteinizing hormone and testosterone levels in dogs, but reversible effects on sperm morphology were induced in this species. There were no statistically significant (P > 0·05) effects on the weight of the pituitaries, testes or secondary sex organs of either species. The only lesion detectable by conventional histological examination was focal atrophy of seminiferous tubules in one rat examined 13 wk after cessation of CHA treatment. Quantitative assessment of testicular spermatogenesis showed that CHA administration reduced the counts of pachytene spermatocytes, and of early and late spermatids, in both species. These effects were apparently reversible in dogs but not in rats.