Effect of the PAPP-A on left ventricular hypertrophy and the intervention of γ-interferon in the spontaneously hypertensive rat

Objective:To observe the effect of pregnancy-associated plasma protein-A(PAPP-A) on left ventricular hypertrophy(LVH) and the intervention of γ-interferon(INF-γ) in the spontaneously hypertensive rat(SHR).Method:Twenty-eight SHR were randomly divided into 4 groups(n=7): high-dose group(SHR-H),middle dose group(SHR-M),low-dose group(SHR-L) and the SHR control group(SHR-C).SHR-L,SHR-M and SHR-H were injected INF-γ respectively for 8 weeks.SHR-C group and WKY group [7 Wistar-Kyoto(WKY) rats were selected as WKY control group(WKY,n=7)] were injected normal saline for 8 weeks.The tail arterial systolic blood pressure(SBP) of the rats and the level of PPAP-A were measured at the time of pre-therapy, 4 week of the treatment and 8 week.At the eighth week,they were sacrificed.We weighed the left ventricular of the hearts and calculated the left ventricular weight index.We observed the morphological changes in myocardial tissue with HE staining.The expression of PAPP-A protein was analysed by Western blot.Result:①At the time of pre-therapy,the different of SBP and PAPP-A was significantly higher in all SHR group than WKY group(P0.05).After 4 weeks,SBP and PAPP-A in SHR-H group and after 8 weeks,SBP and PAPP-A in SHR-M was significantly lower than SHR-C group of the same time(P0.05);but significantly higher than WKY group(P0.05).②LVW and LVMI in all SHR group was significantly higher than WKY group(P0.05).LVW and LVMI was decreased significantly after using high doses of INF-γ.③To observe HE stained sections by optical microscope: the normal myocardial cells,non-mesenchymal cells hyperplasia in WKY group.Myocardial cells and fibers was disorder in SHR group.This change of histology was inhibited in all group by usingINF-γ with the most effective in high-dose group.④The correlation analysis of PAPP-A and LVMI showed that they had a significant positive correlation(R=0.911,P0.05).⑤Comparison with WKY group,the expression of PAPP-A in the myocardial tissue of all SHR group,was increased significantly(P0.05).Comparison with SHR-C group,PAPP-A was decreased significantly in SHR-M group and SHR-H group(P0.05) after 8 weeks.Conclusion:PAPP-A is increased in SHR and inhibited by INF-γ with dependent on the doses.