Melamine exposure from the weaning period negatively affects cardiac histopathology and connexin-43/cardiac troponin-I expression.

Melamine (MEL) gained global attention years ago following hospitalizaiton of hundreds of thousands of infants due to contamination of baby formula, which had been adulterated to falsely elevate protein content. This study aimed to investigate the effects of MEL e exposure on heart tissue starting from the weaning period. Eighteen female rats in the weaning period (21 days) were divided into 3 groups. The control group received 0.1ml of saline orally for 3 weeks. The other two groups received 50 and 75mg/kg MEL e in 0.1ml saline for 3 weeks, respectively. On 45th day, the rats were euthanized under anesthesia, and their heart tissue was removed and placed in neutral formalin. Histopathological analysis of hematoxylin & eosin (H&E), Masson's trichrome, periodic acid schiff (PAS), reticulin stained cardiac tissue, anti-connexin 43 (Cx43) and anti-cardiac troponin I (cTnI) positivity were evaluated. The findings showed that 50mg/kg MEL e increased myocardial damage, congestion, and inflammatory cell infiltration, while exposure to 75mg/kg MEL e increased myocardial damage, inflammatory cell infiltration, congestion, and fibrosis in the perivascular area, as well as decreasing cTnI and Cx43. In conclusion, MEL exposure from the weaning period or early postnatal period may cause structural and functional impairments in the heart tissue, including histological changes, as well as impairments in cTnI associated with contraction units and Cx43 units responsible for impuls transmission.