Prenatal nicotine exposure induces cardiac fibrosis in adult male offspring / 中国药理学与毒理学杂志

ABSTRACT

OBJECTIVE To investigate the effect of prenatal nicotine exposure on cardiac ejection function and myocardial fibrosis of the offspring of rats.METHODS Pregnant rats were sc given nicotine 6.0 mg· kg-1,once daily for 17 d.The body mass and heart mass of the offspring were detected at the 21th day of gestation,and 15 and 90 d after birth.Heart rate of 90 d offspring was recorded by ECG,and cardiac functions were detected by Doppler ultrasonography,including cardiac output (CO),stroke volume (SV),ejection fraction (EF),left ventricular long axis shortening fraction (FS),interventricular septum diastolic diameter (IVSd) and left ventricular posterior wall diastolic diameter (LVPWd).The myocardial ultrastructure was detected under an electron microscope.Masson staining was used to detect the myocardial collagen fiber deposition.The level of collagen protein type Ⅰ in heart tissue was detected by radioimmunoassay.RESULTS Compared with control group,prenatal nicotine exposure resulted in a decrease of heart mass and body mass in groups of 21 d fetal rats and 15 d offspring(P＜0.05,P＜0.01),but had no effect on the 90 d offspring.Compared with the normal control group,the heart rate of 90 d offspring increased [366+10 vs (418+10) min-1] (P＜0.05),CO,FS and EF decreased (P＜0.01),and IVSd and LVPWd increased (P＜0.05,P＜0.01).Electron microscopy revealed that in the heart of nicotine 90 d offspring,myocardial fiber arrangement was loosened and confused,while extracellular matrix increased.Masson staining showed collagen deposited in the myocardium.The level of collagen type Ⅰ in heart tissue increased [0.59±0.09 vs (0.40±0.05) tμg·g-1 tissue] (P＜0.01).CONCLUSION Prenatal nicotine exposure induces the increased level of cardiac collagen type Ⅰ,myocardial fibrosis and decrease of cardiac ejection function in adult offspring,which may lead to increased susceptibility to cardiovascular diseases.