SZCZECIN, Poland—Supplementation with L-ascorbic acid and/or tocopherol positively influenced electrophysiological parameters of the colon of rats chronically exposed to lead, according to a recent study conducted by scientists from Pomeranian Medical University, Szczecin. They published their results in the Dec. 16 issue of Medical Science Monitor (2010;17(1):BR16-26).
In the study, rat colons were subjected to chronic exposure (9 months) to 0.1% lead acetate in drinking water then received dietary supplementation with with L-ascorbic acid (500 mg/L), tocopherol (3 mg/kg b.w.), and/or a water soluble analog of tocopherol (Trolox) (48 mg/L). The electrophysiological parameters of the colon wall were measured with Ussing methods; lead content in the whole blood was analyzed by graphite furnace atomic absorption spectrometry (GFAAS) using Zeeman correction; and L-ascorbic acid and tocopherol in plasma were measured by high performance liquid chromatography (HPLC). In addition, immunohistochemical reaction was carried out for visualization of occludin, the intracellular tight junction protein
Researchers found lead exposure significantly inhibited the electrophysiological parameters, changes in intestinal permeability, disappearance of junctional occludin, decreased amount of mucus covering the colon surface, and the accumulation of PAS-positive substance in the apical region of the cytoplasm in the absorptive colon cells. While supplementation with tocopherol or Trolox did not exert a beneficial influence on the studied parameters, L-ascorbic acid positively influenced the examined electrophysiological parameters, halting the inhibitory influence of lead on ion transport in the rat colon and protecting against tight junction disruption of epithelial cells in the colon of the lead-treated rats. A similar effect was observed in the group of rats receiving lead and supplemented with L-ascorbic acid plus Trolox
