A 6-week oral gavage toxicity study of a novel galacto-oligosaccharide in juvenile rats

A novel galacto-oligosaccharide (GOS) was administered by gavage to groups (10 males and 10 females) of Sprague-Dawley specific pathogen-free rats for 6 weeks from day 4 after birth at doses of 0, 500, 1000, or 2000 mg/kg/day. Each pup was subjected to a variety of observations to examine for development effects/changes after birth: general condition, clinical signs, functional examinations, grip strength and spontaneous movement, body weight and feed consumption, external differentiation, ophthalmological examination, urinalysis (including water consumption), hematology, blood chemistry, necropsy, organ weight, and histopathology. During the study period, no deaths occurred in any group and there were no observed effects from administration of GOS. Therefore, it was concluded that GOS had no effects on the development of animals 4 days after birth. Since, there were no abnormalities due to administration of GOS in the macroscopic examination, organ weight or histopathology of the reproductive organs or differentiation (incisor eruption and eyelid opening) of males or females, it was concluded that repeated oral administration of GOS at 2000 mg/kg/day for 6 weeks from day 4 after birth had : no effects on postnatal development. The no observed effect level of GOS by repeated oral administration for 6 weeks from day 4 after birth was 2000 mg/kg/day for both males and females under the conditions of this study.