EFFECTS OF POSTNATAL METHYLMALONATE ADMINISTRATION ON NEUROBEHAVIORALDEVELOPMENT OF RATS

Administration of methylmalonic acid in rats has been used as a model for methylmalonicacidemia in humans. Nestling Wistar rats of both sexe s received 5 injections daily at 3-h intervals (starting at 7:30 a.m.) of saline or methylmalonic acid (MMA, 10 mg/ml) in a volume of 9 mu l /g body weight per injection subcutaneously in the lumbar region from the 5th to the 9th day of life and 11 mu l/g from day 10 to 14. Growth and neuromotor development were assessed by monitoring the following parameters daily in 54 rats: body weight, ear unfolding, incisor erupt ion, eye opening, righting, palmar grasp, negative geotaxis, cliff avo idance, free-fall righting and startle reflex. The only statistically significant effects of MMA administration were on the day of appearanc e of the free-fall righting reflex: MMA, 12.44 +/- 1.55 vs 11.0 +/- 0. 39 days for saline control (P<0.05, by two-way ANOVA) and a significan t decrease in weight (P<0.05, by ANOVA with repeated measures). The re sults suggest that chronic MMA administration to rats has a selective effect on neuromotor development.