Effect of Melamine Administration during Pregnancy on Foetal Bone Ossification

Abstract

Aim: We aimed to study the effects of prenatal administration of two doses of melamine on foetal ossification centers in rats. Methods: Positively-mated, virgin, adult female Sprague-Dawley rats (n=24) were treated from day 6 to day 20 of gestation with solvent (control), melamine 300 mg/kg/day (group 1) or melamine 450 mg/kg/day (group 2). On day 21, half of the fetuses were examined for bone ossification abnormalities. Results: A total of 109 foetal skeletons were examined. The percentage of incomplete or absent bones in the entire skeleton was significantly less in group 1 and group 2 compared to control. These findings were more prominent in group 2 compared to group 1. Likewise, ossified centers were fewer in the sternum and metacarpal bones in group 1 and group 2 compared to control. No abnormal ossification was observed in metatarsal, skull, pubic or rib bones. Regarding the vertebral centrae, a significant increase in the number of absent or delayed bones was noticed only in group 2 compared to control. Specifically, the abnormalities were observed in the thoracic and sacral centrae. Similarly, group 2 was associated with fewer ossified centers in vertebral arch compared to control. The abnormal ossifications were observed in sacral and coccygeal bones. The only observed abnormality in vertebral ossification in group 1 was in coccygeal arch, compared to control. Conclusions: Prenatal administration of melamine caused dose-dependent retardation in bone ossification, which mainly affected the sternum, metacarpal, vertebral centraee and arch.