Chronic Exposure to Heavy Metals Results in Significant Changes in Expression of Stress Proteins

Chronic exposure to heavy metals, such as arsenic, cadmium and lead, causes serious health issues and reproductive impairment. Therefore, the heavy metal exposure and its resultant stress may change the expression of some genes. Thus, this work aims to find the differential expression pattern of stress proteins such as heat shock protein 70 (HSP70) and metallothioneins (MT1 and MT2) in testes and liver tissue of juvenile and adult rats after chronic treatment of these heavy metals. In general, testicular tissue was selected to review the reproductive health, and liver was selected as the tissue for drug and metal detoxification. Triplicate sets of male Wistar rats both juvenile (15 days old) and adult (2 months old) were taken as treated study subjects. They were supplied drinking water having heavy metal salts of dose 100 times higher than maximum contamination limit, as sole water source, for 3 months. Similarly, triplicate sets of age-matched controls were supplied heavy metal-free distilled water for same duration. After treatment period, semi-quantitative RT-PCR was done to study the expression level of above-mentioned stress proteins in testes and liver in all subjects. Results showed that there was a consistent and significant increase in expression of MT1 compared to controls (p < 0.05), especially in liver tissue after chronic exposure to heavy metals. Overall, this work corroborates that chronic exposure of heavy metal at early age can cause a serious health impact on later stage of life.