Cardiac Effects of Combined Lead Exposure and Chronic Restraint Stress: Alterations in Biomarkers and Myocardial Health

Abstract

Lead is a toxic metal and an environmental pollutant that has been associated with an increased incidence of cardiovascular diseases while restraint stress is a psychological stress model that can also potentially induce deleterious effects on cardiac functions. The aim of this study is to investigate the cardiac effects of acute lead acetate administration and restraint stress exposure in female Wistar rats. Twenty-four (24) female Wistar rats weighing 180 - 240 grams were randomly divided into four (4) groups (n=6): Control (CTL), Restraint stress alone (RSA), Lead acetate alone (LDA), Lead + Restraint stress (LRS). The duration of the study was 21 days. The LDA group were orally administered 100mg/kg of lead acetate, the RSA group were restrained for 1 hour daily and the LRS were administered lead acetate and restrained for 1 hour daily. Twenty-four hours post last lead administration and restraint exposure, the animals were anesthetized and the electrocardiograph (ECG) of the animals were measured. Thereafter, all animal was sacrificed. Blood was collected via cardiac puncture for biochemical analysis. Results showed altered cardiac conductivity including blood pressure, ECG (heart rate, P-wave, QRS complex) in the animals. Serum creatine kinase (CK), lactate dehydrogenase (LDH) and troponin I (TnI) levels were significantly increased (p<0.05) in RSA and LDA groups when compared with control indicating myocardial damage. The LRS group showed a significant increase (p<0.05) in CK, LDH and cTnI levels when compared with control, lead alone and restraint alone groups. In conclusion, this study showed that exposure to restraint stress and lead has a deleterious effect on cardiovascular function of female Wistar rats.