Chlorella Vulgaris Increases Excretion of Hazard Substances in Rats Exposed to Cadmium or Dioxin

Abstract

The unicellular algae chlorella has been a popular food supplement worldwide, especially in Korea, Japan, and the U.S. It has also been used in a variety of practical applications in biotechnology and medical science. Cadmium (Cd) and dioxin have a long biological half-life in organs, and they are present in most human food stuffs, as well as almost all animal tissues. We designed the experiment to elucidate the effect of Chlorella vulgaris on the chelation of Cd and dioxin and on the bioelement homeosis in the body.

- Sevenety male rats(5 weeks old, n=10 rats/group) were divided into three groups: A control group (Con) with 0 ppm of CdCl2 in drinking water, and two groups with 10 or 50 ppm of CdCl2 in drinking water. Each Cd treated group was subdivided into three groups receiving 0% or 5% or a 10% of CV treated group, yielding a total of 7 groups. All rats had free access to water and diet for 8 weeks. Cd alone treated groups had significantly (P<0.05) higher hepatic Cd and MTs concentration, compared to CV treated groups. The hepatic MT I/II mRNA was expressed in all experimental rats. MT II was more expressed in CV treated groups than in Cd alone treated group. Cd levels in liver and the kidney and feces were increased in dose-dependent manner. Cd level in CV treated groups was decreased, while Ca, Fe, Mg and Zn concentration was increased in liver and kidney. Therefore, this study suggests that CV would have a protective effect on Cd-induced liver damage by reducing Cd accumulation and stimulating the expression of MT II in liver. Increased levels of Cd disturb the homeostasis of bioelements, while CV stabilizes the homeostasis of bioelements.

- Fifty rats (6 weeks old, n=10 rats/group) were randomly divided into one control group (Con) and four 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) treated groups that were orally administered 0.5 ㎍/b.w.kg of TCDD dissolved in corn oil once after a period of acclimatization. The TCDD groups included a CV free diet (D-0C), 2% CV (D-2C), 5% CV (D-5C) or 10% CV diet (D-10C). All rats had free access to water and diet for 4 weeks. A significant increase in both PCB 138 and 153 in urinary level was detected in CV treated groups. The hepatic accumulation of TCDD was decreased in the CV treaed groups on CV dose-defendant manner, compared to the D-0C (p<0.05). On the fecal excretion of TCDD was increased in the CV treated groups on CV dose-defendant manner, compared to the D-0C(p<0.05). The expression of hepatic CYP1A1/1A2, AhR mRNA was decreased in CV treated groups compared to the D-0C. Also histopathology(H&E and Oil Red O stains) exchange by TCDD toxicity was observed in rat liver of D-0C compare to CV treated groups..

Chlorella vulgaris alleviates Cd intoxication due to the reduction of Cd concentrations and stimulation of Cd-MT binds and MT II mRNA in the liver. CV stimulates the excretion of Cd out of the body via feces and urine. CV may decrease body burden of Cd in conditions of simultaneous exposure to Cd. CV can change biooelement metabolism in rats exposed to Cd by either/both the result of direct or/and indirect actions of CV. CV may be useful in inhibiting liver damage and promoting the excretion of TCDD and PCBs from the body. Chlorella vulgaris has the potential to eliminate Cd and dioxin, and alleviate cellular toxicity. Further work is needed to examine these effects in a longer study and elucidate the molecular mechanisms by which CV inhibits Cd and dioxin accumulation and reduce toxicity in body.