| Objective To observe abnormal heart rate of neonatal rats by creating a model of Congenital heart defect (CHD) induced by homocys-teine in neonatal rats and to investigate the relationship between morphologic damages by Hcy and expression state of Serum response factor (SRF) at both mRNA and protein level.Methods The 40 pregnant Sprague-Dawley rats were randomly assigned to 4 groups, which were low dose group of l%Hcy(Group-A),high dose group of 2%Hcy (Group-B), intervention group of FA (2%Hcy+ FA+VitB12,Group-C) and control group of Normal Saline (Group-D). Each group had 10 pregnant rats. These rats in Group-A,Group-B and Group-C were injected intraperitoneally with Hcy from the 7th day to the 17th day of pregnancy,the dosage of which was as follows:A-l%Hcy 0.1ml/10g.Wt/d, B-2%Hcy 0.1ml/10g.Wt/d, C-2%Hcy 0.1ml/10g.Wt/d, D-the same amount of saline. Rats in Group-C were also administrated to FA 0.05mg/10g.Wt/d and VitB12 1mg/10g.Wt/d from the first pregnant day to the day of delivery,which was dissolved in water. The hearts of neonatal rats of each group were observed by stereoscope on the day when they are born naturally. Two neonatal rats with CHD in Group-A, Group-B, Group-C, and two neonatal rats without CHD in Group-D, were selected to be observed by light microscope and electron microscope. RNA extraction was performed from one part of heart in neonatal rats of each group. The mRNA expression of SRF in hearts of these neonatal rats of each group were detected by Real-time quantitative PCR. Expression of SRF protein in hearts of these neonatal rats of each group were demonstrated by immunohistochemical staining.Results1. The difference of the average number of births among the 4 groups is significant(p <0.01),and the average number of births of each group was 12.1,9.0,11.6 and 13.6 respectively. The average number of births of Group-D was significantly higher than that of Group-A, Group-B and Group-C respectively, p<0.01. The difference of average number of births between A,B and C are significant(p < 0.01).2. The differences of the abnormal heart incidence of neonatal rats among the 4 group is different, which were 9.17%, 13.50%, 9.65% and 0.74% respectively. The abnormal heart rate of nenoatal rats in Group-D was significantly lower than that of Group-A,Group-B and Group-C respectively, p < 0.01. The abnormal heart rate of nenoatal rats of A, B and C was not significant(p>0.05).3. Under the light microscope and electron microscope, the degree of apoptosis in nenoatal rats with CHD of Group-A, Group-B and Group-C were significantly severer than that of Group-D. The Group-B was the severest. 4. The mRNA expression of SRF in hearts of neonatal rats in 4 groups was different. By comparing the expression levels between neonatal rats with CHD and those without CHD included in the same groups and in the different groups, we calculated p<0.01. A comparison of the expression levels in Group-B & Group-A or Group-B & Group-C,the result was p<0.01. There was no deference among neonatal rats without CHD in 4 groups. The down-regulation of SRF mRNA may cause cardiovascular abnormality of neonatal rats. The dosage of Hcy was negatively correlated with mRNA expression level of SRF in hearts of neonatal rats, p=0.001.5. Protein expression of SRF in hearts of neonatal rats in 4 groups were different. By comparing the expression levels between neonatal rats with CHD and those without CHD included in the same groups and in the different groups, we calculated p<0.01. A comparison of the expression levels in Group-B & Group-A or Group-B & Group-C, the result was p< 0.01. There was no deference among neonatal rats without CHD in 4 groups. The SRF protein was downregulated in neonatal rats with CHD. The dosage of Hcy was negatively correlated with protein expression level of SRF in hearts of neonatal rats, p<0.001.Conclusion1. Hcy cause the damage to nenoatal rats in both embryotoxicity and cytotoxicity. 2. Hcy can downregulate SRF mRNA and protein in neonatal rats hearts and the dosage of Hcy was negatively correlated with mRNA and protein expression level of SRF;the low expression of SRF mRNA and protein maybe related to CHD in nenoatal rats .3. FA and VitB12 intervention during pregnancy may reduce embryotoxicity and cytotoxicity of Hcy. |
