Effects of a Subchronic Intoxication with Cadmium in the Hippocampus of Rats Fed a Soybean-Based Diet

Abstract

Experimental and population studies have shown that sub chronic exposure tocadmium (Cd) causes severe toxic effects in several organs including in the brain,but information on the effects in the hippocampus (Hp) is rare. Soybean is animportant source of protein and isoflavones. Herein we hypothesized that a subchronic cadmium-intoxication throughout the drinking water can cause oxidative/inflammation changes and apoptosis in the Hp; and that a soybean-based diet(SBD) can modulate these effects. To accomplish this goal, we fed 4 groups offemale Wistar-rats for 60 days as follows: casein-based diet + tap water (CBD);CBD + tap water with 15 ppm Cd (CBD + Cd); soybean-based diet + tap water(SBD); and SBD + tap water with 15 ppm Cd (SBD + Cd). After the treatment,molecular markers of oxidative stress, inflammation, and apoptosis were measuredin serum and Hp tissue. Compared to the Hp of CBD fed rats, the Hp of CBDCd showed an apoptotic profle (high p53 and high Bax / Bcl-2 ratio). However,an SBD caused a pro-apoptosis pattern, i.e, increased p53 and Bax expression,reduced Bcl-2 expression and increased Bax / Bcl-2 ratio. Regardless increasedantioxidant enzymes, Cd exposure in SBD fed rats had a synergistic effect in lipidperoxidation and protein oxidation in the Hp. Taking together our data suggest thatan SBD and Cd-exposure have a synergistic effect on oxidative stress/inflammationand apoptosis in Hp. Caution may be taken on using soybean as a source of proteinin patients exposed to Cd.