RESUMO
Objective@# To explore the preventive effect of nicotinamide (NAM) on cleft palate induced by all-trans retinoic acid (RA), to provide research evidence for the prevention of cleft palate. @*Methods @#The mouse cleft palate model was induced by intragastric administration of 70 mg/kg all-trans retinoic acid at embryonic day 10.5 (E10.5) in the control group. The mouse cleft palate model was treated by caudal vein injection of 20 mg/kg NAM at E8.5 to E13.5 in the experimental group (1). The cleft palate model was treated by caudal vein injection of 40 mg/kg NAM at E8.5-E13.5 in the experimental group (2). The cleft palate of fetal rats was observed by laparotomy on E16.5 and statistically analyzed. Annexin V-FITC/PI double staining was used to detect the apoptosis of mouse embryonic palatal mesenchyme (MEPM) cells treated with RA 1 μmol/L (RA 1 group), NAM 200 μmol/L (NAM 200 group), and both NAM 200 μmol/L and RA 1 μmol/L (NAM 200+RA 1 group) for 24 hours by flow cytometry and the apoptosis rate in groups were compared. Culture without RA or NAM was used as a control. @*Results @# The cleft palate rate in the control group was 98%. The cleft palate rate in experimental group (1) was 87%. There was no significant difference between groups (P>0.05). The cleft palate rate in the experimental group (2) was 63%, compared with the control group, there was a significant difference (P<0.01). The cell apoptosis rate was 16.53%±2.89% in the CONTROL group. The cell apoptosis rate was 22.9%±1.85% in the RA 1 group, which was a significant increase compared with the CONTROL group (P<0.01). The apoptotic rate of the NAM 200 group was 9.23%±1.39%, which was a significant decrease compared with NA 1 group (P<0.01). The apoptosis rate of the NAM 200+RA 1 group was 14.9%±7.67%, which was a significant decrease compared with the RA 1 group (P<0.01).@*Conclusion@#NAM can prevent cleft palate. 40 mg/kg nicotinamide during pregnancy is an effective concentration for the prevention of RA-induced cleft palate. The mechanism by which NAM prevents cleft palate may be that NAM inhibits RA-induced apoptosis of MEPM cells.